| LIU HUIXIN（りゆう ふいしん） | データ更新日：2024.04.24 |
教授 ／
理学研究院
地球惑星科学部門
流体圏・宇宙圏科学
| 1. | Florian Günzkofer, Huixin Liu, Gunter Stober, Dimitry Pokhotelov, Claudia Borries, Evaluation of the Empirical Scaling Factor of Joule Heating Rates in TIE‐GCM With EISCAT Measurements, Earth and Space Science, 10.1029/2023EA003447, 2024.04. |
| 2. | Juliana Jaen, Toralf Renkwitz, Huixin Liu, Christoph Jacobi, Robin Wing, Aleš Kuchař, Masaki Tsutsumi, Njål Gulbrandsen, Jorge L. Chau, Long-term studies of the summer wind in the mesosphere and lower thermosphere at middle and high latitudes over Europe, Atmospheric Chemistry and Physics, 10.5194/acp-23-14871-2023, 2023.12. |
| 3. | Brett A. Carter, Noé Lugaz, Steven K. Morley, Jennifer Gannon, Shasha Zou, Huixin Liu, Space Weather in the Popular Media, and the Opportunities the Upcoming Solar Maximum Brings, Space Weather, 10.1029/2023SW003819, 2023.12. |
| 4. | Noé Lugaz, Huixin Liu, Brett A. Carter, Jennifer Gannon, Shasha Zou, Steven K. Morley, New Space Companies Meet a “Normal” Solar Maximum, Space Weather, 10.1029/2023SW003702, 2023.09. |
| 5. | Juliana Jaen, Toralf Renkwitz, Huixin Liu, Christoph Jacobi, Robin Wing, Aleš Kuchař, Masaki Tsutsumi, Njål Gulbrandsen, Jorge L. Chau, Long-term studies of the summer wind in the mesosphere and lower thermosphere at middle and high latitudes, 10.5194/egusphere-2023-1465, 2023.07. |
| 6. | Yihui Cai, Xinan Yue, Wenbin Wang, Shun‑Rong Zhang, Huixin Liu, Dong Lin, Haonan Wu, Jia Yue, Sean L. Bruinsma, Feng Ding, Zhipeng Ren, Libo Liu, Altitude extension of NCAR-TIEGCM (TIEGCM‑X) and evaluation, Space Weather, 10.5194/egusphere-egu23-12894, 2023.05. |
| 7. | 1. Tang, Q., C. Zhou, Huixin Liu, , Low Altitude Tailing Es (LATTE): Analysis of Sporadic-E Layer Height at Different Latitudes of Middle and Low Region, Space Weather, https://doi.org/10.1029/2022SW003323, 2023.05. |
| 8. | Juliana Jaen, Toralf Renkwitz, Jorge Chau, Huixin Liu, Christoph Jacobi, Masaki Tsutsumi, Njål Gulbrandsen, Long-term study of the summer wind variability in the mesosphere and lower thermosphere over nearly two decades at middle and high latitudes, 10.5194/egusphere-egu23-8579, 2023.05. |
| 9. | J. L. Gannon, S. Morley, N. Lugaz, H. Liu, B. Carter, S. Zou, Long‐Term Support Is Needed for Crucial Ground‐Based Sensor Networks, Space Weather, 10.1029/2023SW003529, 2023.05. |
| 10. | Qiong Tang, Chen Zhou, Huixin Liu, Yi Liu, Jiaqi Zhao, Zhibin Yu, Lianhuan Hu, Zhengyu Zhao, Xueshang Feng, Low Altitude Tailing Es (LATTE): Analysis of Sporadic‐E Layer Height at Different Latitudes of Middle and Low Region, Space Weather, 10.1029/2022SW003323, 2023.04. |
| 11. | Masaru Kogure, Huixin Liu, Hidekatsu Jin, Impact of Tropospheric Ozone Modulation Due To El Niño on Tides in the MLT, Geophysical Research Letters, 10.1029/2023GL102790, 2023.03. |
| 12. | Dexin Ren, Jiuhou Lei, Han‐Li Liu, Wenbin Wang, Jia Yue, Huixin Liu, Influence of Mesospheric Gravity Wave Drag on the Formation of Winter Helium Bulge in the Thermosphere, Journal of Geophysical Research: Space Physics, 10.1029/2022JA031022, 2023.02. |
| 13. | S. K. Morley, H. Liu, B. A. Carter, J. L. Gannon, N. Lugaz, Credit Where Credit Is Due: Data and Software in the Space Weather Community, Space Weather, 10.1029/2022SW003371, 2022.12. |
| 14. | F. Günzkofer, D. Pokhotelov, G. Stober, H. Liu, H.‐L. Liu, N. J. Mitchell, A. Tjulin, C. Borries, Determining the Origin of Tidal Oscillations in the Ionospheric Transition Region With EISCAT Radar and Global Simulation Data, Journal of Geophysical Research: Space Physics, 10.1029/2022JA030861, 2022.10. |
| 15. | Qiong Tang, Chen Zhou, Huixin Liu, Zhitao Du, Yi Liu, Jiaqi Zhao, Zhibin Yu, Zhengyu Zhao, Xueshang Feng, Global Structure and Seasonal Variations of the Tidal Amplitude in Sporadic‐E Layer, Journal of Geophysical Research: Space Physics, 10.1029/2022JA030711, 2022.10. |
| 16. | Qiong Tang, Chen Zhou, Huixin Liu, Yi Liu, Jiaqi Zhao, Zhibin Yu, Zhengyu Zhao, Xueshang Feng, Latitudinal Dependence of the Geomagnetic and Solar Activity Effect on Sporadic-E layer, 10.5194/acp-2022-534, 2022.09. |
| 17. | Masaru Kogure, Huixin Liu, Chihiro Tao, Mechanisms for Zonal Mean Wind Responses in the Thermosphere to Doubled CO 2 Concentration, Journal of Geophysical Research: Space Physics, 10.1029/2022JA030643, 2022.09. |
| 18. | Noé Lugaz, Jennifer L. Gannon, Shasha Zou, Steven K. Morley, Huixin Liu, Brett A. Carter, Michael Hapgood, 2024 Decadal Survey for Space and Solar Physics: Space Weather Inputs, Space Weather, 10.1029/2022SW003181, 20, 8, 2022.08. |
| 19. | Noé Lugaz, Brett A. Carter, Jennifer L. Gannon, Michael Hapgood, Huixin Liu, T. Paul O’Brien, Steven K. Morley, Shasha Zou, Thank You to Our 2021 Peer Reviewers, Space Weather, 10.1029/2022SW003116, 20, 4, 2022.04. |
| 20. | Mike Hapgood, Huixin Liu, Noé Lugaz, SpaceX—Sailing Close to the Space Weather? , Space Weather, 10.1029/2022SW003074, 2022.03. |
| 21. | 齊藤, 昭則, 阿部, 琢美, 松岡, 彩子, 石坂, 圭吾, 齋藤, 義文, 田川, 雅人, 熊本, 篤志, 斎藤, 享, 西岡, 未知, 細川, 敬祐, 横山, 竜宏, HUIXIN, Liu, SAITO, Akinori, ABE, Takumi, MATSUOKA, Ayako, ISHISAKA, Keigo, SAITO, Yoshifumi, TAGAWA, Masato, KUMAMOTO, Atsushi, SAITO, Susumu, NISHIOKA, Michi, HOSOKAWA, Keisuke, YOKOKAWA, Tatsuhiro, 昼間スポラディックE層形成過程の中性大気とプラズマ大気の同時観測による解明—Elucidation of the generation process of daytime sporadic E Layers by simultaneous observation of the neutral and ionized atmospheres, 観測ロケットシンポジウム2021 講演集 = Proceedings of Sounding Rocket Symposium 2021, 2022.03, 第4回観測ロケットシンポジウム（2022年3月14-15日. ハイブリッド開催（JAXA相模原キャンパス& オンライン）) 4th Sounding Rocket Symposium(March 14-15, 2022. Hybrid(in-person & online) Conference (Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 著者人数: 12名 資料番号: SA6000175010 レポート番号: Ⅱ-5. |
| 22. | K. H. Pham, B. Zhang, K. Sorathia, T. Dang, W. Wang, V. Merkin, H. Liu, D. Lin, M. Wiltberger, J. Lei, S. Bao, J. Garretson, F. Toffoletto, A. Michael, J. Lyon, Thermospheric Density Perturbations Produced by Traveling Atmospheric Disturbances During August 2005 Storm , Journal of Geophysical Research: Space Physics, 10.1029/2021JA030071, 2022.02. |
| 23. | Yihui Cai, Xinan Yue, Wenbin Wang, Shun‐Rong Zhang, Huixin Liu, Jiuhou Lei, Zhipeng Ren, Yiding Chen, Feng Ding, Dexin Ren, Ionospheric Topside Diffusive Flux and the Formation of Summer Nighttime Ionospheric Electron Density Enhancement Over Millstone Hill , Geophysical Research Letters, 10.1029/2021GL097651, 2022.02. |
| 24. | Yihui Cai, Xinan Yue, Wenbin Wang, Shun‐Rong Zhang, Huixin Liu, Jiuhou Lei, Zhipeng Ren, Yiding Chen, Feng Ding, Dexin Ren, Ionospheric Topside Diffusive Flux and the Formation of Summer Nighttime Ionospheric Electron Density Enhancement Over Millstone Hill, Geophysical Research Letters, 10.1029/2021GL097651, 49, 4, 2022.02. |
| 25. | K. H. Pham, B. Zhang, K. Sorathia, T. Dang, W. Wang, V. Merkin, H. Liu, D. Lin, M. Wiltberger, J. Lei, S. Bao, J. Garretson, F. Toffoletto, A. Michael, J. Lyon, Thermospheric Density Perturbations Produced by Traveling Atmospheric Disturbances During August 2005 Storm, Journal of Geophysical Research: Space Physics, 10.1029/2021JA030071, 127, 2, 2022.02. |
| 26. | Michael A. Hapgood, Huixin Liu, Noé Lugaz, SpaceX - sailing close to the space weather?, Space Weather, 10.1002/essoar.10510636.1, 2022.02. |
| 27. | Qiong Tang, Chen Zhou, Huixin Liu, Yi Liu, Jiaqi Zhao, Zhibin Yu, Zhengyu Zhao, Xueshang Feng, The Possible Role of Turbopause on Sporadic‐E Layer Formation at Middle and Low Latitudes , Space Weather, 10.1029/2021SW002883, 2021.12. |
| 28. | Noé Lugaz, Huixin Liu, Mike Hapgood, Steven Morley, Machine‐Learning Research in the Space Weather Journal: Prospects, Scope, and Limitations , Space Weather, 10.1029/2021SW003000, 2021.12. |
| 29. | Ales Kuchar , Gunter Stober , Christoph Jacobi , Dimitry Pokhotelov , Huxin Liu , Han-Li Liu , Kathrin Baumgarten , Peter Brown , Diego Janches , Damian Murphy , Alexander Kozlovsky , Mark Lester , Evgenia Belova , Johan Kero , Nicholas Mitchell , Tracy Motffat-Griffin, Long-term changes in mesospheric wind and wave estimates based on radar observations in both hemispheres, DACH, 10.5194/dach2022-81, 2021.12. |
| 30. | Benedikt Gast, Ales Kuchar, Gunter Stober, Christoph Jacobi, Dimitry Pokhotelov, Huxin Liu, Han-Li Liu, Kathrin Baumgarten, Peter Brown, Diego Janches, Damian Murphy, Alexander Kozlovsky, Mark Lester, Evgenia Belova, Johan Kero, Nicholas Mitchell, Tracy Motffat-Griffin, Superposed epoch analysis of coupling mechanisms captured by meteor radars during sudden stratospheric warmings , DACH, 10.5194/dach2022-84, 2021.12. |
| 31. | Ales Kuchar, Gunter Stober, Christoph Jacobi, Dimitry Pokhotelov, Huxin Liu, Han-Li Liu, Kathrin Baumgarten, Peter Brown, Diego Janches, Damian Murphy, Alexander Kozlovsky, Mark Lester, Evgenia Belova, Johan Kero, Nicholas Mitchell, Tracy Motffat-Griffin, Long-term changes in mesospheric wind and wave estimates based on radar observations in both hemispheres, 10.5194/dach2022-81, 2021.12. |
| 32. | Noé Lugaz, Huixin Liu, Mike Hapgood, Steven Morley, Machine‐Learning Research in the Space Weather Journal: Prospects, Scope, and Limitations, Space Weather, 10.1029/2021SW003000, 19, 12, 2021.12. |
| 33. | Qiong Tang, Chen Zhou, Huixin Liu, Yi Liu, Jiaqi Zhao, Zhibin Yu, Zhengyu Zhao, Xueshang Feng, The Possible Role of Turbopause on Sporadic‐E Layer Formation at Middle and Low Latitudes, Space Weather, 10.1029/2021SW002883, 19, 12, 2021.12. |
| 34. | Benedikt Gast, Ales Kuchar, Gunter Stober, Christoph Jacobi, Dimitry Pokhotelov, Huxin Liu, Han-Li Liu, Kathrin Baumgarten, Peter Brown, Diego Janches, Damian Murphy, Alexander Kozlovsky, Mark Lester, Evgenia Belova, Johan Kero, Nicholas Mitchell, Tracy Motffat-Griffin, Superposed epoch analysis of coupling mechanisms captured by meteor radars during sudden stratospheric warmings, 10.5194/dach2022-84, 2021.12. |
| 35. | Yihui Cai, Wenbin Wang, Shun‐Rong Zhang, Xinan Yue, Zhipeng Ren, Huixin Liu, Climatology Analysis of the Daytime Topside Ionospheric Diffusive O + Flux Based on Incoherent Scatter Radar Observations at Millstone Hill, Journal of Geophysical Research: Space Physics, 10.1029/2021JA029222, 2021.10. |
| 36. | Gunter Stober, Ales Kuchar, Dimitry Pokhotelov, Huixin Liu, Han-Li Liu, Hauke Schmidt, Christoph Jacobi, Kathrin Baumgarten, Peter Brown, Diego Janches, Damian Murphy, Alexander Kozlovsky, Mark Lester, Evgenia Belova, Johan Kero, Nicholas Mitchell, Interhemispheric differences of mesosphere–lower thermosphere winds and tides investigated from three whole-atmosphere models and meteor radar observations, Atmospheric Chemistry and Physics, 10.5194/acp-21-13855-2021, 2021.09. |
| 37. | Masaru Kogure, Huixin Liu, DW1 Tidal Enhancements in the Equatorial MLT During 2015 El Niño: The Relative Role of Tidal Heating and Propagation, Journal of Geophysical Research: Space Physics, 10.1029/2021ja029342, 126, 7, 2021.07, Ground-based and satellite observations have shown that the tidal component DW1 in the equatorial mesosphere and lower thermosphere (MLT) was enhanced in July–October 2015, which was an intense El Niño year. This enhancement is reproduced in the 21 years reanalysis-driven model simulation by the Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA). Our analysis shows the (1,1) Hough mode dominates this tidal enhancement, and its peak amplitude was 7.4 K (74%) higher than that under neutral (non-ENSO) conditions at 90 km. The corresponding tidal heating was found to increase by 0.4 mWkg−1 (5%), which can explain 0.5 K (7%) of the (1,1) enhancement. To explain the remaining 6.9 K (93%) of the enhancement, we quantitively examined the upward propagation condition by calculating the vertical wavenumber and the latitudinal shear of the zonal wind. The analysis reveals that the vertical wavenumber between 18 and 60 km was one standard deviation smaller than that under neutral conditions. The latitudinal zonal wind shear also decreased at 18 N/S° in 18–30 km. These results suggest smaller dissipation and damping of the (1,1) mode during its upward propagation, which dominantly contributed to the tidal enhancement at 90 km altitude. This decrease in the vertical wavenumber and the wind shear can be reasonably explained by the eastward phase of the quasi-biennial oscillation (QBO) in the lower stratosphere. This study suggests that the overlapping of the 2015 El Niño with the eastward phase of the QBO induced the large enhancement of the DW1.. |
| 38. | Masaru Kogure, Jia Yue, Huixin Liu, Gravity Wave Weakening During the 2019 Antarctic Stratospheric Sudden Warming, Geophysical Research Letters, 10.1029/2021GL092537, 48, 8, 2021.04. |
| 39. | Noé Lugaz, Delores J. Knipp, Jennifer L. Gannon, Michael Hapgood, Huixin Liu, T. Paul O'Brien, Steven K. Morley, Thank You to Our 2020 Reviewers, Space Weather, 10.1029/2021SW002756, 18, 3, 2021.04. |
| 40. | Huixin Liu, Yosuke Yamazaki, Jiuhou Lei, Day‐to‐Day Variability of the Thermosphere and Ionosphere, Space Physics and Aeronomy Collection Volume 4: Upper Atmosphere Dynamics and Energetics, Geophysical Monograph 261, 10.1002/9781119815631.ch15, 275-300, 2021.03. |
| 41. | Lihui Qiu, Xiaomin Zuo, Tao Yu, Yangyi Sun, Huixin Liu, Lingfeng Sun, Biqiang Zhao, The Characteristics of Summer Descending Sporadic E Layer Observed With the Ionosondes in the China Region, Journal of Geophysical Research: Space Physics, 10.1029/2020JA028729, 126, 3, 2021.03. |
| 42. | Larisa P. Goncharenko, V. Lynn Harvey, Huixin Liu, Nicholas M. Pedatella, Sudden Stratospheric Warming Impacts on the Ionosphere– Thermosphere System: A Review of Recent Progress, Space Physics and Aeronomy Collection Volume 3: Ionosphere Dynamics and Applications, Geophysical Monograph 260, 10.1002/9781119815617.ch16, 369-400, 2021.03. |
| 43. | 斉藤, 昭則, 阿部, 琢美, 石坂, 圭吾, 田川, 雅人, 熊本, 篤志, 齋藤, 義文, 松岡, 彩子, 斎藤, 享, 西岡, 未知, 細川, 敬祐, 横山, 竜宏, HUIXIN, Liu, SAITO, Akinori, ABE, Takumi, ISHISAKA, Keigo, TAGAWA, Masato, KUMAMOTO, Atsushi, SAITO, Yoshifumi, MATSUOKA, Ayako, SAITO, Susumu, NISHIOKA, Michi, HOSOKAWA, Keisuke, YOKOKAWA, Tatsuhiro, 昼間スポラディックE層形成過程の中性大気とプラズマ大気の同時観測による解明, 観測ロケットシンポジウム2020 講演集 = Proceedings of Sounding Rocket Symposium 2020, 2021.03, 第3回観測ロケットシンポジウム（2021年3月24-25日. オンライン開催) 3rd Sounding Rocket Symposium (March 24-25, 2021. Online Meeting) 著者人数: 12名 資料番号: SA6000162010 レポート番号: Ⅲ-3. |
| 44. | Huixin Liu, C. Tao, H. Jin, T. Abe, Geomagnetic activity effects on CO2-driven trend in the thermosphere and ionosphere: ideal model experiments with GAIA, J. Geophys. Res. , 10.1029/2020JA028607, 126, 2021.01, [URL]. |
| 45. | L. Qiu, X. Zuo, T. Yu, Y. Sun, Huixin Liu, L. Sun, B. Zhao, The characteristics of summer descending sporadic E layer observed with the ionosondes in the China region, J. Geophys. Res. , 10.1029/2020JA028729, 48, 2021.01, [URL]. |
| 46. | Huixin Liu, Chihiro Tao, Hidekatsu Jin, Takamichi Abe, Geomagnetic Activity Effects on CO2 ‐Driven Trend in the Thermosphere and Ionosphere: Ideal Model Experiments With GAIA, Journal of Geophysical Research: Space Physics, 10.1029/2020ja028607, 126, 1, 2021.01, We examine impacts of geomagnetic activity (GA) on CO -driven trend in the ionosphere and thermosphere using the Ground-to-topside Atmosphere Ionosphere model for Aeronomy whole atmosphere model. The model reveals three salient features. (1) Geomagnetic activities usually weakens the CO -driven trend at a fixed altitude. Among the IT parameters analyzed, the thermosphere mass density is the most robust indicator for CO cooling effect even with GA influences. (2) Geomagnetic activities can either strengthen or weaken the CO -driven trend in hmF2 and NmF2, depending on local time and latitudes. This renders the widely used linear fitting methods invalid for removing geomagnetic effects from observations. (3) An interdependency exists between the efficiency of CO forcing and geomagnetic forcing, with the former enhances at lower GA level, while the latter enhances at higher CO concentration. This could imply that the CO -driven trend would accelerate in periods of declining GA, while magnetic storms may have larger space weather impacts in the future with increasing CO . These findings provide a preliminary model framework to understand interactions between the CO forcing from below and the geomagnetic forcing from above. 2 2 2 2 2 2 2 2 2. |
| 47. | Heikki Vanhamäki, Astrid Maute, Patrick Alken, Huixin Liu, Dipolar elementary current systems for ionospheric current reconstruction at low and middle latitudes, Earth, Planets and Space, 10.1186/s40623-020-01284-1, 72, 1, 2020.12, The technique of spherical elementary current systems (SECS) is a powerful way to determine ionospheric and field-aligned currents (FAC) from magnetic field measurements made by low-Earth-orbiting satellites, possibly in combination with magnetometer arrays on the ground. The SECS method consists of two sets of basis functions for the ionospheric currents: divergence-free (DF) and curl-free (CF) components, which produce poloidal and toroidal magnetic fields, respectively. The original CF SECS are only applicable at high latitudes, as they build on the assumption that the FAC flow radially into or out of the ionosphere. The FAC at low and middle latitudes are far from radial, which renders the method inapplicable at these latitudes. In this study, we modify the original CF SECS by including FAC that flow along dipolar field lines. This allows the method to be applied at all latitudes. We name this method dipolar elementary current systems (DECS). Application of the DECS to synthetic data, as well as Swarm satellite measurements are carried out, demonstrating the good performance of this method, and its applicability to studies of ionospheric current systems at low and middle latitudes.. |
| 48. | Noé Lugaz, Jennifer Gannon, Michael Hapgood, Huixin Liu, T Paul O'Brien, Space Weather as the Nexus of Applied and Fundamental Space Science: The Need for Separate Funding Mechanisms and Definition, Space Weather, 10.1029/2020SW002695, 2020.12. |
| 49. | Saurav Aryal, J. S. Evans, John Correira, Alan G. Burns, Wenbin Wang, Stanley C. Solomon, Fazlul I. Laskar, William E. McClintock, Richard W. Eastes, Tong Dang, Jiuhou Lei, Huixin Liu, Geonhwa Jee, First Global‐Scale Synoptic Imaging of Solar Eclipse Effects in the Thermosphere, Journal of Geophysical Research: Space Physics, 10.1029/2020ja027789, 125, 9, 2020.09. |
| 50. | Tao Yu, Hailun Ye, Huixin Liu, Chunliang Xia, Xiaomin Zuo, Xiangxiang Yan, Na Yang, Yangyi Sun, Biqiang Zhao, Ionospheric F Layer Scintillation Weakening as Observed by COSMIC/FORMOSAT‐3 During the Major Sudden Stratospheric Warming in January 2013, Journal of Geophysical Research: Space Physics, 10.1029/2019JA027721, 125, 9, 2020.09. |
| 51. | Aryal, S., J. S. Evans, J. Correira, T. Dang, J. Lei, Huixin Liu, G. Jee, A. G. Burns, W. Wang, S. C. Solomon, F. I. Laskar, W. E. McClintock, R. W. Eastes, First global-scale synoptic imaging of a solar eclipse in the thermosphere, J. Geophys. Res. , 10.1029/2020JA027789, 47, 2020.06, [URL]. |
| 52. | Yu, T. H. Ye, Huixin Liu, C. Xia, X. Zuo, X. Yan, N. Yang, Y. Sun, B. Zhao, , Ionospheric F-layer scintillation weakening as observed by COSMIC/FORMOSAT-3 during the major sudden stratospheric warming in January 2013, J. Geophys. Res., https://doi.org/10.1029/2019JA027721, 2020.06, [URL]. |
| 53. | Kogure, M., Yue J., Huixin Liu, Gravity wave weakening during the 2019 Antarctic stratospheric sudden warming, Geophys. Res. Lett., 10.1029/2021GL092537, 48, 2020.06, [URL]. |
| 54. | Vanhamaki, H., A. Maute, P. Alken, Huixin Liu, Dipolar elementary current systems for ionospheric current reconstruction at low and middle latitudes, Earth, Planets and Space, https://doi.org/10.1186/s40623-020-01284-1, 72, 2020.06, [URL]. |
| 55. | Huixin Liu, C. Tao, H. Jin, Y. Nakamoto, Circulation and tides in a cooler upper atmosphere: dynamical effects of CO2-doubling, Geophys. Res. Lett., 10.1029/2020GL087413, 47, 2020.05, [URL]. |
| 56. | Huixin Liu, Chihiro Tao, Hidekatsu Jin, Yusuke Nakamoto, Circulation and Tides in a Cooler Upper Atmosphere: Dynamical Effects of CO 2 Doubling, Geophysical Research Letters, 10.1029/2020GL087413, 47, 10, 2020.05, Thermosphere cooling is a known effect of increasing CO2 in the atmosphere. In this study, we explore the changes of thermosphere circulation and tides in the cooled thermosphere via a doubled CO2 numerical experiment using the Ground-to-topside Atmosphere Ionosphere model for Aeronomy (GAIA). The results reveal three major features. (1) The thermosphere cools about 10 K more around solstices than equinoxes, more at the summer pole than the winter pole. (2) The meridional circulation shifts downward and strongly accelerates by 5-15 m s(-1). (3) The tidal activity experiences dramatic changes, with a 40-60% reduction in the semidiurnal tides (SW2) throughout the thermosphere but an 30-50% enhancement in diurnal tides (DW1) below 200 km altitude. The nonmigrating tide DE3 has only minor changes. These changes in temperature, meridional circulation, and tides are persistent features in all seasons and can profoundly affect the spatial distribution and diurnal cycles of the ionospheric responses to CO2 doubling via atmosphere composition and electrodynamics.. |
| 57. | Zhang, R., L. Liu, Huixin Liu, Interhemispheric transport of the ionospheric F region plasma during the 2009 sudden stratosphere warming, Geophys. Res. Lett., 10.1029/2020GL087078, 47, 2020.03, [URL]. |
| 58. | Noé Lugaz, Delores J. Knipp, Jennifer L. Gannon, Michael Hapgood, Huixin Liu, T. Paul O'Brien, Daniel T. Welling, Thank You to Our 2019 Reviewers, Space Weather, 10.1029/2020SW002481, 18, 3, 2020.03, [URL], Peer reviewing is the foundation of modern scholarship, with external specialists being asked to fairly check and evaluate submitted work. This difficult and often time-consuming activity is performed voluntarily, with the understanding that one's own scholarship shall benefit down the line from a careful analysis of its assumption, results, accuracy, and yes, language, as we are now evaluating someone else's work. At Space Weather, we pride ourselves on a fair but quick review process yielding high-quality articles with a time from submission to first decision of under one month. This would not be possible without the hard work of all our reviewers. Once a year, we take the occasion to name these women and men in order to thank them for their service to the journal and the community.. |
| 59. | Ruilong Zhang, Libo Liu, Huixin Liu, Huijun Le, Yiding Chen, Hui Zhang, Interhemispheric Transport of the Ionospheric F Region Plasma During the 2009 Sudden Stratosphere Warming, Geophysical Research Letters, 10.1029/2020GL087078, 47, 6, 2020.03. |
| 60. | Hisashi Hayakawa, Frédéric Clette, Toshihiro Horaguchi, Tomoya Iju, Delores J Knipp, Huixin Liu, Takashi Nakajima, Sunspot observations by Hisako Koyama: 1945–1996, 492, 3, 4513-4527, 2020.03. |
| 61. | Hayakawa, H., F. Clette, T. Horaguchi, T. Iju, D. Knipp, Huixin Liu, T. Nakajima, Sunspot observations by Hisako Koyama: 1945-1996, Monthly Notice of Royal Astronomical Society, doi:10.1093/mnras/stz3345, 47, 2020.02, [URL]. |
| 62. | Philippe Baron, Satoshi Ochiai, Eric Dupuy, Richard Larsson, Huixin Liu, Naohiro Manago, Donal Murtagh, Shin Ichiro Oyama, Hideo Sagawa, Akinori Saito, Takatoshi Sakazaki, Masato Shiotani, Makoto Suzuki, Potential for the measurement of mesosphere and lower thermosphere (MLT) wind, temperature, density and geomagnetic field with Superconducting Submillimeter-Wave Limb-Emission Sounder 2 (SMILES-2), Atmospheric Measurement Techniques, 10.5194/amt-13-219-2020, 13, 1, 219-237, 2020.01, [URL], Submillimeter-Wave Limb-Emission Sounder 2 (SMILES-2) is a satellite mission proposed in Japan to probe the middle and upper atmosphere (20-160 km). The main instrument is composed of 4K cooled radiometers operating near 0.7 and 2 THz. It could measure the diurnal changes of the horizontal wind above 30 km, temperature above 20 km, ground-state atomic oxygen above 90 km and atmospheric density near the mesopause, as well as abundance of about 15 chemical species. In this study we have conducted simulations to assess the wind, temperature and density retrieval performance in the mesosphere and lower thermosphere (60- 110 km) using the radiometer at 760 GHz. It contains lines of water vapor (H2O), molecular oxygen (O2) and nitric oxide (NO) that are the strongest signals measured with SMILES-2 at these altitudes. The Zeeman effect on the O2 line due to the geomagnetic field (B) is considered; otherwise, the retrieval errors would be underestimated by a factor of 2 above 90 km. The optimal configuration for the radiometer's polarization is found to be vertical linear. Considering a retrieval vertical resolution of 2.5 km, the line-of-sight wind is retrieved with a precision of 2-5ms-1 up to 90 km and 30ms-1 at 110 km. Temperature and atmospheric density are retrieved with a precision better than 5K and 7% up to 90 km (30K and 20% at 110 km). Errors induced by uncertainties on the vector B are mitigated by retrieving it. The retrieval of B is described as a side-product of the mission. At high latitudes, precisions of 30-100 nT on the vertical component and 100-300 nT on the horizontal one could be obtained at 85 and 105 km (vertical resolution of 20 km). SMILES-2 could therefore provide the first measurements of B close to the electrojets' altitude, and the precision is enough to measure variations induced by solar storms in the auroral regions.. |
| 63. | Philippe Baron, Satoshi Ochiai, Eric Dupuy, Richard Larsson, Huixin Liu, Naohiro Manago, Donal Murtagh, Shin-ichiro Oyama, Hideo Sagawa, Akinori Saito, Takatoshi Sakazaki, Masato Shiotani, Makoto Suzuki, Potential for the measurement of mesosphere and lower thermosphere (MLT) wind, temperature, density and geomagnetic field with Superconducting Submillimeter-Wave Limb-Emission Sounder 2 (SMILES-2), Atmospheric Measurement Techniques, 10.5194/amt-13-219-2020, 13, 1, 219-237, 2020.01, Submillimeter-Wave Limb-Emission Sounder 2 (SMILES-2) is a satellite mission proposed in Japan to probe the middle and upper atmosphere (20-160 km). The main instrument is composed of 4K cooled radiometers operating near 0.7 and 2 THz. It could measure the diurnal changes of the horizontal wind above 30 km, temperature above 20 km, ground-state atomic oxygen above 90 km and atmospheric density near the mesopause, as well as abundance of about 15 chemical species. In this study we have conducted simulations to assess the wind, temperature and density retrieval performance in the mesosphere and lower thermosphere (60-110 km) using the radiometer at 760 GHz. It contains lines of water vapor (H2O), molecular oxygen (O-2) and nitric oxide (NO) that are the strongest signals measured with SMILES-2 at these altitudes. The Zeeman effect on the O-2 line due to the geomagnetic field (B) is considered; otherwise, the retrieval errors would be underestimated by a factor of 2 above 90 km. The optimal configuration for the radiometer's polarization is found to be vertical linear. Considering a retrieval vertical resolution of 2.5 km, the line-of-sight wind is retrieved with a precision of 2-5 m s(-1) up to 90 km and 30 m s(-1) at 110 km. Temperature and atmospheric density are retrieved with a precision better than 5K and 7% up to 90 km (30K and 20% at 110 km). Errors induced by uncertainties on the vector B are mitigated by retrieving it. The retrieval of B is described as a side-product of the mission. At high latitudes, precisions of 30-100 nT on the vertical component and 100-300 nT on the horizontal one could be obtained at 85 and 105 km (vertical resolution of 20 km). SMILES-2 could therefore provide the first measurements of B close to the electrojets' altitude, and the precision is enough to measure variations induced by solar storms in the auroral regions.. |
| 64. | Yang Yi Sun, Huixin Liu, Yasunobu Miyoshi, Loren C. Chang, Libo Liu, Correction to El Niño–Southern Oscillation effect on ionospheric tidal/SPW amplitude in 2007–2015 FORMOSAT- 3/COSMIC observations (Earth, Planets and Space, (2019), 71, 1, (35), 10.1186/s40623-019-1009-7), earth, planets and space, 10.1186/s40623-019-1025-7, 71, 1, 2019.12, [URL]. |
| 65. | Yang Yi Sun, Huixin Liu, Yasunobu Miyoshi, Loren C. Chang, Libo Liu, Niño–Southern Oscillation effect on ionospheric tidal/SPW amplitude in 2007–2015 FORMOSAT-3/COSMIC observations, earth, planets and space, 10.1186/s40623-019-1009-7, 71, 1, 2019.12, [URL]. |
| 66. | Mamoru Yamamoto, Wayne K. Hocking, Satonori Nozawa, Juha Vierinen, Huixin Liu, Nozomu Nishitani, Special issue “Recent Advances in MST and EISCAT/Ionospheric Studies – Special Issue of the Joint MST15 and EISCAT18 Meetings, May 2017”, earth, planets and space, 10.1186/s40623-019-1070-2, 71, 1, 2019.12, [URL]. |
| 67. | Yihui Cai, Xinan Yue, Wenbin Wang, Shunrong Zhang, Libo Liu, Huixin Liu, Weixing Wan, Long-Term Trend of Topside Ionospheric Electron Density Derived From DMSP Data During 1995–2017, Journal of Geophysical Research: Space Physics, 10.1029/2019JA027522, 124, 12, 10708-10727, 2019.12, [URL], In recent decades, significant efforts have been made to characterize and understand the global pattern of ionospheric long-term trend. However, little attention has been paid to the topside ionosphere trend. In this study, the unique in situ data measured by series Defense Meteorological Satellite Program (DMSP) satellites were utilized to derive the long-term trend of the topside ionosphere for the first time. We checked carefully data quality, gap, and consistency between different satellites for both electron density and ion temperature, and compared the techniques of artificial neuron network (ANN) and multiple linear regression methods for deriving the trend. The electron density (Ne) trend in the middle and low latitudes at ~860 km around 18 MLT was derived using the ANN method from 1995–2017. The trend from DMSP observations has a mean magnitude ranging from ~ − 2% to ~2% per decade, with clear seasonal, latitude and longitude variations. The derived trend was evaluated by directly comparing with the simulated trend at 500 km from the NCAR-TIEGCM driven by realistic changes of CO2 level and geomagnetic field. The observed and simulated trends have similar geographic distribution patterns at 18 MLT. The good agreement between the observed trend around 860 km and the simulated trend near 500 km implies that the physical processes controlling the Ne trends above the peak height might be identical. Further control simulations show that the geomagnetic field secular variation is the dominant factor of the electron density trend at around 500 km, rather than the CO2 long-term enhancement.. |
| 68. | Mamoru Yamamoto, Wayne K. Hocking, Satonori Nozawa, Juha Vierinen, Huixin Liu, Nozomu Nishitani, Special issue “Recent Advances in MST and EISCAT/Ionospheric Studies – Special Issue of the Joint MST15 and EISCAT18 Meetings, May 2017”, Earth, Planets and Space, 10.1186/s40623-019-1070-2, 71, 1, 2019.12. |
| 69. | Libin Weng, Jiuhou Lei, Huixin Liu, Xiankang Dou, Hanxian Fang, Thermospheric Density Cells at High Latitudes as Observed by GOCE Satellite Preliminary Results, Geophysical Research Letters, 10.1029/2019GL084951, 46, 21, 11615-11621, 2019.11, [URL]. |
| 70. | Libin Weng, Jiuhou Lei, Huixin Liu, Xiankang Dou, Hanxian Fang, Thermospheric Density Cells at High Latitudes as Observed by GOCE Satellite: Preliminary Results, Geophysical Research Letters, 10.1029/2019GL084951, 46, 21, 11615-11621, 2019.11, This study provides a climatological view of density cell structures at high latitudes in the lower thermosphere, using neutral mass density at 270 km derived from Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite. Three types of the density cells named isolated low, isolated high, and wavy density cells are analyzed. Our results revealed that the density cell structures generally occur in the Northern Hemisphere and the local summer, but they are less frequently observed in the Southern Hemisphere. The low density cell tends to have greater occurrence in the dawn side than in other sampled local times, while the high and wavy density cells occur more frequently in the morning side in terms of the GOCE trajectory. Moreover, the characteristics of density cell structures, including the central locations, horizontal scales, and relative magnitudes, strongly depend on the type of the density cell structure. These results can serve as a baseline to further validate the theoretical models and also to improve our understanding of the density variability of the lower thermosphere at high latitudes.. |
| 71. | Mamoru Yamamoto, Wayne K. Hocking, Satonori Nozawa, Juha Vierinen, Huixin Liu, Nozomu Nishitani, Special issue "Recent Advances in MST and EISCAT/Ionospheric Studies - Special Issue of the Joint MST15 and EISCAT18 Meetings, May 2017" PREFACE, EARTH PLANETS AND SPACE, 10.1186/s40623-019-1070-2, 71, 1, 2019.09. |
| 72. | Zheng Wang, Huixin Liu, Jiankui Shi, Guojun Wang, Xiao Wang, Plasma Blobs Concurrently Observed With Bubbles in the Asian‐Oceanian Sector During Solar Maximum, Journal of Geophysical Research: Space Physics, 10.1029/2018JA026373, 124, 8, 7062-7071, 2019.08, With simultaneous ionospheric measurements from ROCSAT-1 satellite and ground ionosondes/GPS receivers, three cases of concurrent plasma blobs and bubbles in the same magnetic meridian were observed around 22:30 LT in Asian-Oceanian sector during solar maximum. Two cases were observed: equatorial spread F (ESF) over Vanimo station (geog. 2.7 degrees S, 141.3 degrees E; geom. 11.2 degrees S, 146.2 degrees W) and plasma blobs around 8.0 degrees S (geom.) on 1 June and 6 October 2003. The other case observed equatorial spread F over Hainan station (geog. 19.5 degrees N, 109.1 degrees E; geom. 9.1 degrees N, 179.1 degrees W) and plasma blob near the dip equator on 8 March 2004. Plasma blobs were all observed near 600-km height near the equator. Equatorial spread F and amplitude scintillations from the ground stations were observed near the same magnetic meridian, indicating the existence of bubbles. Considering that both plasma bubbles and blobs are field-aligned elongated structures, magnetic field line mapping shows that in the two cases at Vanimo, blobs were above bubbles, providing direct observational evidence for blob formation in the intermediate stage of plasma bubble evolution; in the case at Hainan, the blob and bubble were likely at similar height, and it could be generated by gravity wave.. |
| 73. | Tatsuhiro Yokoyama, Hidekatsu Jin, Hiroyuki Shinagawa, Huixin Liu, Seeding of Equatorial Plasma Bubbles by Vertical Neutral Wind, Geophysical Research Letters, 10.1029/2019GL083629, 46, 13, 7088-7095, 2019.07, [URL]. |
| 74. | Tatsuhiro Yokoyama, Hidekatsu Jin, Hiroyuki Shinagawa, Huixin Liu, Seeding of Equatorial Plasma Bubbles by Vertical Neutral Wind, Geophysical Research Letters, 10.1029/2019GL083629, 46, 13, 7088-7095, 2019.07, The seeding mechanism of equatorial plasma bubbles (EPBs) in the ionosphere has not been fully understood for several decades. Before investigating the complex seeding process by atmospheric gravity waves, which have been considered as a possible candidate, we investigate the vertical neutral wind effect on the EPB seeding by making the numerical simulation setup as simple as possible. It is presented that the vertical wind over the dip equator with an amplitude of as low as 5 m/s can seed EPBs effectively. The upward wind reduces the eastward current and produces the eastward polarization electric field, so that the bottomside F region pushed by the upward wind is going to form upwellings and penetrate into the topside F region accelerated by the Rayleigh-Taylor instability. It is suggested that the vertical wind perturbations driven by gravity waves should play an important role in seeding EPBs.. |
| 75. | Klemens Hocke, Huixin Liu, Nicholas Pedatella, Guanyi Ma, Global sounding of F region irregularities by COSMIC during a geomagnetic storm, Annales Geophysicae, 10.5194/angeo-37-235-2019, 37, 2, 235-242, 2019.04, [URL]. |
| 76. | Sun Yang-Yi, Liu Huixin, Miyoshi Yasunobu, Chang Loren C, Liu Libo, El Nino-Southern Oscillation effect on ionospheric tidal/SPW amplitude in 2007-2015 FORMOSAT- 3/COSMIC observations (vol 71, 35, 2019), EARTH PLANETS AND SPACE, 10.1186/s40623-019-1025-7, 71, 2019.04. |
| 77. | Klemens Hocke, Huixin Liu, Nicholas Pedatella, Guanyi Ma, Global sounding of F region irregularities by COSMIC during a geomagnetic storm, Annales Geophysicae, 10.5194/angeo-37-235-2019, 37, 2, 235-242, 2019.04. |
| 78. | A. C. Moral, K. Shiokawa, S. Suzuki, Huixin Liu, Y. Otsuka, C. Y. Yatini, Observations of low-latitude travelling ionospheric disturbances by a 630.0-nm airglow imager and the CHAMP satellite over Indonesia, J. Geophys. Res., https://doi.org/10.1029/2018JA025634, 63, 8, 2623-2637, 2019.03, [URL]. |
| 79. | Huixin Liu, M. Tsutsumi, Hanli Liu, Vertical structure of terdiurnal tides in the Antarctic MLT region: 15-year observation over Syowa (69S, 39E), Geophys. Res. Lett., 10.1029/2018JA025634, 46, 2019.03, [URL]. |
| 80. | Huixin Liu, H. Hayakawa, J. Isa, 小山ひさ子氏: アマチュア天文家から 世界的な太陽観測者へ の道程, 天文月報, 112, 3, 193-198, 2019.03, [URL]. |
| 81. | Daniel T. Welling, Delores J. Knipp, Michael Hapgood, Huixin Liu, T. Paul O'Brien, Thank You to Our 2018 Peer Reviewers, Space Weather, 10.1029/2019SW002194, 17, 3, 372-374, 2019.03, [URL]. |
| 82. | Huixin Liu, Masaki Tsutsumi, Hanli Liu, Vertical Structure of Terdiurnal Tides in the Antarctic MLT Region 15-Year Observation Over Syowa (69°S, 39°E), Geophysical Research Letters, 10.1029/2019GL082155, 46, 5, 2364-2371, 2019.03, [URL]. |
| 83. | Sun Yang-Yi, Liu Huixin, Miyoshi Yasunobu, Chang Loren C, Liu Libo, Nino-Southern Oscillation effect on ionospheric tidal/SPW amplitude in 2007-2015 FORMOSAT-3/COSMIC observations, EARTH PLANETS AND SPACE, 10.1186/s40623-019-1009-7, 71, 2019.03. |
| 84. | Aysegul Ceren Moral, Kazuo Shiokawa, Shin Suzuki, Huixin Liu, Yuichi Otsuka, Clara Yoko Yatini, Observations of Low‐Latitude Traveling Ionospheric Disturbances by a 630.0‐nm Airglow Imager and the CHAMP Satellite Over Indonesia, Journal of Geophysical Research: Space Physics, 10.1029/2018JA025634, 124, 3, 2198-2212, 2019.03, We report the first comparison of ground and satellite measurements of low-latitude traveling ionospheric disturbances (TIDs). Three TID events were simultaneously observed by a 630.0-nm airglow imager and the CHAllenging Minisatellite Payload (CHAMP) satellite at Kototabang, Indonesia (geographic coordinates: 0.2 degrees S, 100.3 degrees E, geomagnetic latitude: 10.6 degrees S). In 630.0-nm airglow images of all three events, there are clear southward-moving structures. Events 1 and 2 are a single pulse with horizontal scales of similar to 500-1,000 km. Event 3 shows five wave fronts with a horizontal scale size of 500-1,000 km. All three TIDs are medium-scale TIDs. Horizontal wavelengths of both airglow intensity at an average emission altitude of 250 km and CHAMP neutral density variations measured at 400 km are estimated by fitting a sinusoidal function to the observed data. The estimated horizontal wavelengths for airglow and neutral density data are 1,031 and 880 km for event 1 and 560 and 420 km for event 3, respectively. These values between airglow and CHAMP are comparable, suggesting both instruments are observing the same wave. For event 1, the CHAMP electron density mapped along the geomagnetic field line onto the airglow altitude does not show wave structure similar to the airglow variation. For events 2 and 3, the plasma density did not show wavy structures similar to the waves seen in the airglow image and CHAMP neutral density. These results suggest that the TIDs observed in airglow images are not caused by ionospheric plasma instability but by gravity waves in the thermosphere.. |
| 85. | Daniel T. Welling, Delores J. Knipp, Michael Hapgood, Huixin Liu, T. Paul O'Brien, Thank You to Our 2018 Peer Reviewers, Space Weather, 10.1029/2019SW002194, 17, 372-374, 2019.03, ©2019. American Geophysical Union. All Rights Reserved. Peer review remains one of the most important service activities for scientists. Through the time-consuming process of peer review, community volunteers set the bar for the quality of science that is shared with each other and with the world. Attentive, patient, and critical review is required to maintain rigorous and accurate scientific reporting. Reviewers donate their time and effort with little incentive outside of the knowledge that they are contributing to sustain scientific rigor. Space Weather is fortunate to be able to continually rely on our reviewers to maintain a journal that receives and publishes high-quality, high-impact articles. We recognize the time, effort, and dedication each review requires. For this, we extend a heartfelt thank you to all of our 2018 reviewers. We sincerely appreciate your choice to respond positively to our review requests. Last year, Space Weather received 785 peer reviews from 354 individuals. The reviewers who contributed three or more reviews are recognized in italics below. Thank you all for your contributions in 2018.. |
| 86. | K. Oyama, C. H. Chen, L. Bankov, D. Minakshi, K. Ryu, J.Y. Liu, Huixin Liu, Precursor effect of March 11 2011 off the coast of Tohoku earthquake on high and low latitude ionospheres and its possible disturbing mechanism, Advances in Space Research, https://doi.org/10.1016/j.asr.2018.12.042, 63, 2019.01, [URL]. |
| 87. | Zheng Wang, Huixin Liu, Jiankui Shi, Guojun Wang, Xiao Wang, Plasma Blobs Concurrently Observed With Bubbles in the Asian-Oceanian Sector During Solar Maximum, Journal of Geophysical Research: Space Physics, 10.1029/2018JA026373, 2019.01, [URL]. |
| 88. | Oyama, K, C. H. Chen, L. Bankov, D. Minakshi, K. Ryu, J.Y. Liu, Huixin Liu, Precursor effect of March 11 2011 off the coast of Tohoku earthquake on high and low latitude ionospheres and its possible disturbing mechanism, Advances in Space Research, 63, 2019.01. |
| 89. | Yang Yi Sun, Huixin Liu, Yasunobu Miyoshi, Libo Liu, Loren C. Chang, El Niño–Southern Oscillation effect on quasi-biennial oscillations of temperature diurnal tides in the mesosphere and lower thermosphere, Earth, Planets and Space, 10.1186/s40623-018-0832-6, 70, 1, 2018.12, [URL]. |
| 90. | Masato Nakamura, Dmitri Titov, Kevin McGouldrick, Pierre Drossart, Jean Loup Bertaux, Huixin Liu, Special issue “Akatsuki at Venus The First Year of Scientific Operation”, earth, planets and space, 10.1186/s40623-018-0916-3, 70, 1, 2018.12, [URL]. |
| 91. | M. Nakamura, D. Titov, K. McGouldrick, P. Drossart, J.L. Bertaux, Huixin Liu, Akatsuki at Venus: the first year of scientific operation, Earth, Planets and Space, https://doi.org/10.1186/s40623-018-0916-3, 70, 2018.07, [URL]. |
| 92. | Run Shi, Binbin Ni, Danny Summers, Huixin Liu, Akimasa Yoshikawa, Beichen Zhang, Generation of Electron Acoustic Waves in the Topside Ionosphere From Coupling With Kinetic Alfven Waves A New Electron Energization Mechanism, Geophysical Research Letters, 10.1029/2018GL077898, 45, 11, 5299-5304, 2018.06, [URL]. |
| 93. | Run Shi, Binbin Ni, Danny Summers, Huixin Liu, Akimasa Yoshikawa, Beichen Zhang, Generation of Electron Acoustic Waves in the Topside Ionosphere From Coupling With Kinetic Alfven Waves: A New Electron Energization Mechanism, Geophysical Research Letters, 10.1029/2018GL077898, 45, 11, 5299-5304, 2018.06, Results from a new drift kinetic model in the topside ionosphere capture the mode conversion from kinetic Alfven waves to electron acoustic waves. When the kinetic Alfven waves propagate into the transition region, where the electron density of ionospheric origin becomes comparable to that of magnetospheric origin, the steep temperature gradient leads to the mode conversion. The electron acoustic waves are short-lived by dissipating their energy into the electron energization, thus revealing a new type of electron acceleration in the topside ionosphere.. |
| 94. | Y. Yamazaki, C. Stolle, J. Matzka, Huixin Liu, C. Tao, Interannual Variability of the Daytime Equatorial Ionospheric Electric Field, Journal of Geophysical Research: Space Physics, 10.1002/2017JA025165, 123, 2018.05. |
| 95. | S. Eswaraiah, Yong Ha Kim, Huixin Liu, M. Venkat Ratnam, Jaewook Lee, Do minor sudden stratospheric warmings in the Southern Hemisphere (SH) impact coupling between stratosphere and mesosphere-lower thermosphere (MLT) like major warmings? 3. Space science, Earth, Planets and Space, 10.1186/s40623-017-0704-5, 69, 1, 2017.12, [URL]. |
| 96. | Delores Knipp, Huixin Liu, Hisashi Hayakawa, Ms. Hisako Koyama:From Amateur Astronomer to Long-Term Solar Observer, Space Weather, 10.1002/2017SW001704, 15, 10, 1215-1221, 2017.10, [URL]. |
| 97. | P. Abadi, Y. Otsuka, K. Shiokawa, A. Husin, Huixin Liu, S. Saito, Equinoctial asymmetry in the zonal distribution of scintillation as observed by GPS receivers in Indonesia, Journal of Geophysical Research, 10.1002/2017JA024146, 122, 8, 8947-8958, 2017.08, [URL]. |
| 98. | Huixin Liu, Nicholas Pedatella, Klemens Hocke, Medium-scale gravity wave activity in the bottomside F region in tropical regions, Geophysical Research Letters, 10.1002/2017GL073855, 44, 14, 7099-7105, 2017.07, [URL]. |
| 99. | Huixin Liu, Jeff Thayer, Yongliang Zhang, Woo Kyoung Lee, The non–storm time corrugated upper thermosphere What is beyond MSIS?, Space Weather, 10.1002/2017SW001618, 15, 6, 746-760, 2017.06, [URL]. |
| 100. | N. S.A. Hamid, Huixin Liu, T. Uozumi, Akimasa Yoshikawa, N. M.N. Annadurai, Peak time of equatorial electrojet from different longitude sectors during fall solar minimum, Journal of Physics: Conference Series, 10.1088/1742-6596/852/1/012015, 852, 1, 2017.06, [URL]. |
| 101. | Liu Huixin, Y. Sun, Yasunobu Miyoshi, H. Jin, ENSO effects on MLT diurnal tides: A 21 year reanalysis data-driven GAIA model simulation, J. Geophys. Res, 10.1002/2017JA024011, 122, 2017.05. |
| 102. | L. Liu, Liu Huixin, H. Le, Y. Chen, Y. Sun, B. Ning, L. Hu, W. Wan, N. Li, J. Xiong, Mesospheric temperatures estimated from the meteor radar observations at Mohe, China, J. Geophys. Res, 10.1002/2016JA023776, 122, 2017.03. |
| 103. | Y. Yamazaki, Liu Huixin, Y. Sun, Yasunobu Miyoshi, M. Kosch, M. Mlynczak, Quasi-biennial oscillation of the ionospheric wind dynamo, J. Geophys. Res, 10.1002/2016JA023684, 122, 2017.03. |
| 104. | L. Liu, Liu Huixin, Y. Chen, H. Le, Y. Sun, B. Ning, L. Hu, W. Wan, Variations of the meteor echo heights at Beijing and Mohe, J. Geophys. Res, 10.1002/ 2016JA023448, 122, 2017.01. |
| 105. | K. I. Oyama, M. Devi, K. Ryu, C. H. Chen, J. Y. Liu, H. Liu, L. Bankov, T. Kodama, Modifications of the ionosphere prior to large earthquakes report from the Ionosphere Precursor Study Group, Geoscience Letters, 10.1186/s40562-016-0038-3, 3, 1, 2016.12, [URL], The current status of ionospheric precursor studies associated with large earthquakes (EQ) is summarized in this report. It is a joint endeavor of the “Ionosphere Precursor Study Task Group,” which was formed with the support of the Mitsubishi Foundation in 2014–2015. The group promotes the study of ionosphere precursors (IP) to EQs and aims to prepare for a future EQ dedicated satellite constellation, which is essential to obtain the global morphology of IPs and hence demonstrate whether the ionosphere can be used for short-term EQ predictions. Following a review of the recent IP studies, the problems and specific research areas that emerged from the one-year project are described. Planned or launched satellite missions dedicated (or suitable) for EQ studies are also mentioned.. |
| 106. | J. Guo, F. Wei, X. Feng, J. Forbes, Y. Wang, Liu Huixin, W. Wan, Prolonged multiple excitation of large-scale traveling atmospheric disturbances (TADs) by successive and interacting coronal mass ejections, J. Geophys. Res, 10.1002/2015JA022076, 2016.07. |
| 107. | Liu Huixin, E. Doornbos, J. Nakashima, Thermospheric wind observed by GOCE: wind jets and seasonal variations, J. Geophys. Res, 10.1002/2016JA022938, 121, 2016.06. |
| 108. | Jianpeng Guo, F. Wei, Xueshang Feng, Liu Huixin, Weixing Wan, et. al, Alfvén waves as a solar-interplanetary driver of the thermospheric disturbances, Scientific Reports, 10.1038/srep-18895, 2016.05. |
| 109. | K. Ryu, K. Oyama, L. Bankov, C. Chen, M. Devi, Liu Huixin, J. Liu, Precursory enhancement of EIA in the morning sector: contribution from Mid-latitude large earthquake in the north-east Asian region, Adv. in Space. Res, http://dx.doi.org/10.1016/j.asr.2015.08.030, 2016.05. |
| 110. | K. Oyama, M. Devi, K. Ryu, C. Chen, J. Liu, Liu Huixin, L. Bankov, Modifications of the ionosphere prior to large earthquakes: report from the ionosphere precursor study group, Geoscience Letter, doi:10.1186/s40562-016-0038-3, 2016.05. |
| 111. | Liu Huixin, Thermospheric inter-annual variability and its potential connection to ENSO and stratospheric QBO, Earth. Planets and Space, 10.1186/s40623-016-0455-8, 2016.04. |
| 112. | Jianpeng Guo, Fengsi Wei, Xueshang Feng, Huixin Liu, Weixing Wan, Zhiliang Yang, Jiyao Xu, Chaoxu Liu, Alfvén waves as a solar-interplanetary driver of the thermospheric disturbances, Scientific reports, 10.1038/srep18895, 6, 2016.01, [URL], Alfvén waves have been proposed as an important mechanism for the heating of the Sun's outer atmosphere and the acceleration of solar wind, but they are generally believed to have no significant impact on the Earth's upper atmosphere under quiet geomagnetic conditions due to their highly fluctuating nature of interplanetary magnetic field (i.e., intermittent southward magnetic field component). Here we report that a long-duration outward propagating Alfvén wave train carried by a high-speed stream produced continuous (∼2 days) and strong (up to ±40%) density disturbances in the Earth's thermosphere in a way by exciting multiple large-scale gravity waves in auroral regions. The observed ability of Alfvén waves to excite large-scale gravity waves, together with their proved ubiquity in the solar atmosphere and solar wind, suggests that Alfvén waves could be an important solar-interplanetary driver of the global thermospheric disturbances.. |
| 113. | Kwangsun Ryu, Koh Ichiro Oyama, Ludmil Bankov, Chia Hung Chen, Minakshi Devi, Huixin Liu, Jann Yenq Liu, Precursory enhancement of EIA in the morning sector Contribution from mid-latitude large earthquakes in the north-east Asian region, Advances in Space Research, 10.1016/j.asr.2015.08.030, 57, 1, 268-280, 2016.01, [URL], To investigate whether the link between seismic activity and EIA (equatorial ionization anomaly) enhancement is valid for mid-latitude seismic activity, DEMETER observations around seven large earthquakes in the north-east Asian region were fully analyzed (M⩾6.8). In addition, statistical analysis was performed for 35 large earthquakes (M⩾6.0) that occurred during the DEMETER observation period. The results suggest that mid-latitude earthquakes do contribute to EIA enhancement, represented as normalized equatorial N e , and that ionospheric change precedes seismic events, as has been reported in previous studies. According to statistical studies, the normalized equatorial density enhancement is sensitive and proportional to both the magnitude and the hypocenter depth of an earthquake. The mechanisms that can explain the contribution of mid-latitude seismic activity to EIA variation are briefly discussed based on current explanations of the geochemical and ionospheric processes involved in lithosphere–ionosphere interaction.. |
| 114. | Nurul Shazana Abdul Hamid, Huixin Liu, Teiji Uozumi, Akimasa Yoshikawa, Empirical model of equatorial electrojet based on ground-based magnetometer data during solar minimum in fall, EARTH PLANETS AND SPACE, 10.1186/s40623-015-0373-1, 67, 2015.12, In this study, we constructed an empirical model of the equatorial electrojet (EEJ), including local time and longitudinal dependence, based on simultaneous data from 12 magnetometer stations located in six longitude sectors. An analysis was carried out using the equatorial electrojet index, EUEL, calculated from the geomagnetic northward H component. The magnetic EEJ strength is calculated as the difference between the normalized EUEL index of the magnetic dip equator station and the normalized EUEL index of the off-dip equator station located beyond the EEJ band. Analysis showed that this current is always strongest in the South American sector, regardless of local time (LT), and weakest in the Indian sector during 0900 and 1000 LT, but shifted to the African sector during 1100 to 1400 LT. These longitude variations of EEJ roughly follow variations of the inversed main field strength along the dip equator, except for the Indian and Southeast Asian sectors. The result showed that the EEJ component derived from the model exhibits a similar pattern with measured EEJ from ground data during noontime, mainly before 1300 LT.. |
| 115. | N. S.A. Hamid, H. Liu, T. Uozumi, G. K. Gopir, H. A. Hadin, A. Yoshikawa, Longitudinal and solar activity dependence of equatorial electrojet at Southeast Asian sector, 4th International Conference on Space Science and Communication, IconSpace 2015 2015 International Conference on Space Science and Communication Space Technology for Humanity, IconSpace 2015 - Proceeding, 10.1109/IconSpace.2015.7283763, 262-266, 2015.09, [URL], In the E layer of equatorial ionosphere, the equatorial electrojet (EEJ) current interacts with the global Sq current and caused abnormally large amplitude of geomagnetic field component measured at the magnetic dip equator station. In this study, we attempted to separate EEJ and Sq at dip equator using the EUEL index derived from MAGDAS/CPMN stations. Moreover, we normalized the observation data to overcome the uncertainties due to the latitudinal variation of both EEJ and Sq currents which are neglected in most of previous studies. This new approach allowed the study of longitudinal dependence of EEJ. Analysis is performed using data from stations at East and West of Southeast Asian sector for a year of 2011. Additionally, we examined the solar activity dependence of EEJ during this inclining phase of solar cycle.. |
| 116. | Jianpeng Guo, J. Forbes, F. Wei, Xueshang Feng, Liu Huixin, Weixing Wan, et. al, Observations of a large-scale gravity wave propagating over an extremely large horizontal distance in the thermosphere, Geophys. Res. Lett., 10.1002/2015GL065671, 42, 2015.08. |
| 117. | Mohamad Huzaimy Jusoh, Farah Adilah Mohd Kasran, Huixin Liu, Kiyohumi Yumoto, Possible correlation between exogenous parameters and seismicity, 7th International Conference on Recent Advances in Space Technologies, RAST 2015 RAST 2015 - Proceedings of 7th International Conference on Recent Advances in Space Technologies, 10.1109/RAST.2015.7208401, 525-529, 2015.08, [URL], Exogenous parameter is basically referred to the external activities that may have been the important factors in modulating the atmosphere, ionosphere and the earth's surface. Due to its significant impacts, there is possibility to link solar activities and seismicity. Associated investigations have been done by previous researchers in order to explore the solar - terrestrial connection; nevertheless, the physical mechanism is still controversial. To comprehend the investigation of this coupling mechanism, we propose another exogenous source to be analyzed which is cosmic ray. As solar activity, cosmic ray also has minimum and maximum phases or called as cosmic ray cycle, but it is anti-correlation between phases of sunspot and cosmic ray cycles. In this brief report, we examine the trend of shallow earthquake occurrence as the caused effect during recent 4 complete solar cycles (SC 20-23) in order to study its possible link to sun spot number (SSN). The earthquakes were categorized into very shallow earthquakes with epicenter depth less than 35 km and deeper earthquakes with epicenter depth between 35-70 km. For very shallow earthquakes, the analysis shows two interesting features. First, its occurrence rate shows a steady increase during the 40 years period of 1964-2005, with average increase rate about 150/year. Second, a distinct increase of the occurrence rate occurs during each solar minimum of SC 21-23. Neither of these features is found in the earthquakes with deeper epicenters, suggesting that the solar influence on seismicity, if exists, is likely to exist only in the case of very shallow earthquakes whose epicenter is in the crust region.. |
| 118. | Nurul Shazana Abdul Hamid, Huixin Liu, Teiji Uozumi, Kiyohumi Yumoto, Empirical model of equatorial electrojet based on ground-based magnetometer data during solar minimum in fall, Earth. Planets and Space, 10.1186/s40623-015-0373-1, 67, 2015.06. |
| 119. | Nurul Shazana Abdul Hamid, Huixin Liu, Teiji Uozumi, Kiyohumi Yumoto, Longitudinal and Solar Activity Dependence of Equatorial Electrojet At Southeast Asian Sector, IEEE, 262-266, 2015.06. |
| 120. | L. Chang, Liu Huixin, Yasunobu Miyoshi, C. Chen, F. Chang, C. Lin, J. Y. Liu, Y. Y. Sun, Structure and origins of the Weddell Sea Anomaly from tidal and planetary wave signatures in FORMOSAT-3/COSMIC observations and GAIA GCM simulations, J. Geophys. Res., doi:10.1002/2014JA020752, 120, 1325-1340, 2015.02. |
| 121. | Loren C. Chang, Huixin Liu, Yasunobu Miyoshi, Chia Hung Chen, Fu Yuan Chang, Chien Hung Lin, Jann Yenq Liu, Yan Yi Sun, Structure and origins of the Weddell Sea Anomaly from tidal and planetary wave signatures in FORMOSAT-3/COSMIC observations and GAIA GCM simulations, Journal of Geophysical Research: Space Physics, 10.1002/2014JA020752, 120, 2, 1325-1340, 2015.02, [URL], The Weddell Sea Anomaly (WSA) is a recurrent feature of the austral summer midlatitude ionosphere where electron densities are observed to maximize during the local nighttime. In this study, tidal decomposition is applied to FORMOSAT-3 (Formosa Satellite)/Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) total electron content (TEC) and electron density observations between 2007 and 2012 to quantify the components dominating local time and spatial variation in the WSA region. Our results present some of the first three-dimensional spaceborne analyses of the WSA from a tidal perspective over multiple years. We find that the features of the WSA can be reconstructed as the result of superposition between the dominant diurnal standing (D0), eastward wave number 1 (DE1), westward wave number 2 (DW2), and stationary planetary wave 1 (SPW1) components in TECs, producing the characteristic midnight WSA peak. The D0, DE1, DW2, and SPW1 components are found to be an interannually recurring feature of the southern midlatitude to high-latitude ionosphere during the summer, manifesting as enhancements in electron density around 300km altitude of the summer middle to high magnetic latitudes. The phases of the aforementioned nonmigrating diurnal signatures in electron density in this region are near evanescent, suggesting in situ generation, rather than upward propagation from below. However, the SPW1 signature shows some signs of an eastward tilt with altitude, suggesting possible downward propagation. The relation of these components to possible generation via in situ photoionization or plasma transport along magnetic field lines is also discussed using results from the Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA) general circulation model (GCM), connecting the tidal interpretation of the WSA to previously examined generation mechanisms.. |
| 122. | K.-I. Oyama, J. T. Jhou, J. T. Lin, C. Lin, Liu Huixin, Kiyohumi Yumoto, Ionospheric response to 2009 Sudden Stratospheric Warming in the northern hemisphere, J. Geophys. Res., 10.1002/2014JA020014, 119, 1-16, 2014.11. |
| 123. | Nurul Shazana Abdul Hamid, Huixin Liu, Teiji Uozumi, Kiyohumi Yumoto, Relationship between equatorial electrojet and global Sq currents at dip equator region, Earth, Planets and Space, http://www.earth-planets-space.com/content/66/1/146, 66, 1-11, 2014.10. |
| 124. | C. Lin, J. T. Lin, C.H. Chen, J. Y. Liu, Y. Y. Sun, Y. Kakinam, M. Matsumura, Liu Huixin, R. J. Rau, Ionospheric shock waves triggered by rockets, Ann. Geophys., 10.5194/angeo-32-1145-2014, 32, 1145-1152, 2014.09. |
| 125. | C. H. Lin, J. T. Lin, C. H. Chen, J. Y. Liu, Y. Y. Sun, Y. Kakinami, M. Matsumura, W. H. Chen, H. Liu, R. J. Rau, Ionospheric shock waves triggered by rockets, Annales Geophysicae, 10.5194/angeo-32-1145-2014, 32, 9, 1145-1152, 2014.09, This paper presents a two-dimensional structure of the shock wave signatures in ionospheric electron density resulting from a rocket transit using the rate of change of the total electron content (TEC) derived from ground-based GPS receivers around Japan and Taiwan for the first time. From the TEC maps constructed for the 2009 North Korea (NK) Taepodong-2 and 2013 South Korea (SK) Korea Space Launch Vehicle-II (KSLV-II) rocket launches, features of the V-shaped shock wave fronts in TEC perturbations are prominently seen. These fronts, with periods of 100-600 s, produced by the propulsive blasts of the rockets appear immediately and then propagate perpendicularly outward from the rocket trajectory with supersonic velocities between 800-1200 ms(-1) for both events. Additionally, clear rocket exhaust depletions of TECs are seen along the trajectory and are deflected by the background thermospheric neutral wind. Twenty minutes after the rocket transits, delayed electron density perturbation waves propagating along the bow wave direction appear with phase velocities of 800-1200 ms(-1). According to their propagation character, these delayed waves may be generated by rocket exhaust plumes at earlier rocket locations at lower altitudes.. |
| 126. | Jianpeng Guo, Liu Huixin, Xueshang Feng, Weixing Wan, Yue Deng, Chaoxu Liu, Constructive interference of large-scale gravity waves excited by interplanetary shock on 29 October 2003: CHAMP observation, J. Geophys. Res., 10.1002/2014JA020255, 119, 1-6, 2014.08. |
| 127. | Liu Huixin, Yasunobu Miyoshi, Saburo Miyahara, H. Jin, H. Fujiwara, H. Shinagawa, Thermal and dynamical changes of the zonal mean state of the thermosphere during the 2009 SSW: GAIA simulations, J. Geophys. Res., 10.1002/2014JA020222, 119, 1-7, 2014.08. |
| 128. | M. G. 4. Cardinal, Yoshikawa Akimasa, Huixin Liu, Masakazu Watanabe, Kiyohumi Yumoto, Hideaki Kawano, Capacity building: A tool for advancing space weather science, Space Weather, 10.1002/2014SW001110, 12, 2014.08. |
| 129. | Jianpeng Guo, Huixin Liu, Xueshang Feng, Weixing Wan, Yue Deng, Chaoxu Liu, Constructive interference of large-scale gravity waves excited by interplanetary shock on 29 October 2003: CHAMP observation, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1002/2014JA020255, 119, 8, 2014.08, In this paper we report the detection of full constructive interference between two large-scale gravity waves in the upper thermosphere from the CHAMP accelerometer measurements. The two waves are separately excited in northern and southern auroral regions by the shock-induced auroral intensification on 29 October 2003. They propagate equatorward and encounter near the equator, where constructive interference occurs and causes nightside equatorial neutral density enhancements of similar to 60%. This result demonstrates that the constructive interference can be a potential mechanism for large density increases in the equatorial region during magnetically active periods.. |
| 130. | Huixin Liu, Yasunobu Miyoshi, Saburo Miyahara, Hidekatsu Jin, Hitoshi Fujiwara, Hiroyuki Shinagawa, Thermal and dynamical changes of the zonal mean state of the thermosphere during the 2009 SSW: GAIA simulations, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1002/2014JA020222, 119, 8, 2014.08, Changes of the zonal mean state of the thermosphere during the 2009 stratospheric sudden warming (SSW) have been investigated using the Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA) model. Both the zonal mean thermal and dynamical structure of the thermosphere exhibit pronounced changes during the SSW in terms of zonal mean temperature and winds. First, the zonal mean temperature above 100 km altitude drops at all latitudes except for in a narrow band around 60 degrees N. Such temperature perturbations are found to be dominantly caused by changes in direct heating/cooling processes related to solar radiation and thermal heat conduction at high latitudes, but by dynamical processes in tropical regions. Second, the zonal mean zonal wind experiences a strong westward perturbation in the tropical thermosphere, along with distinct change in the meridional circulation. This change consists of two parts. One is a global scale north-to-south flow accompanied with upwelling/downwelling in the northern/southern polar region, the other is a fountain-like flow in tropical lower thermosphere. The large enhancement of semidiurnal tides is suggested to be the primary cause for the fountain-like flow.. |
| 131. | Jianpeng Guo, Liu Huixin, Xueshang Feng, T. I. Pulkkinen, E. I. Tanskanen, Chaoxu Liu, Dingkun Zhong, Yuan Wang, MLT and seasonal dependence of auroral electrojets: IMAGE magnetometer network observations, J. Geophys. Res., 10.1002/2014JA019843, 119, ?-?, 2014.04. |
| 132. | Jianpeng Guo, Huixin Liu, Xueshang Feng, T. I. Pulkkinen, E. I. Tanskanen, Chaoxu Liu, Dingkun Zhong, Yuan Wang, MLT and seasonal dependence of auroral electrojets: IMAGE magnetometer network observations, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1002/2014JA019843, 119, 4, 3179-3188, 2014.04, Total eastward and westward electrojet currents (EEJ and WEJ) and their central latitudes derived from the International Monitor for Auroral Geomagnetic Effects (IMAGE) network magnetic measurements are analyzed for the combined MLT (magnetic local time) and seasonal dependence during the period 1995-2009. EEJ shows a strong MLT variation with significant dependence on season. During summer months the maxima occur around 1600-1800 MLT, whereas during winter months the maxima occur around 1800-2000 MLT. Moreover, the summer maxima are much larger than the winter maxima and appear at higher latitudes. The summer maxima are mainly associated with the solar EUV conductivity effect, while the winter maxima are mainly due to the contribution of northward convective electric field. EEJ exhibits a dominant annual variation with maximum in summer and minimum in winter. WEJ also exhibits a strong MLT variation with significant dependence on season. The maxima occur around 0200-0400 MLT during summer months, around 0000-0200 MLT during winter months, and around 0000-0400 MLT during equinoctial months. Moreover, the equinoctial maxima are much larger than the summer and winter maxima and appear at relatively lower latitudes. The seasonal variations in WEJ are the combinations of annual variations and semiannual variations. Both annual and semiannual variations show significant dependence on MLT. These results increase our knowledge on what factors contribute to the auroral electrojets as well as their magnetic signatures and hence help us better understand the limitations of global auroral electrojet indices, such as the AE and SME indices.. |
| 133. | Jianpeng Guo, T. I. Pulkkinen, E. I. Tanskanen, Xueshang Feng, Barbara A. Emery, Liu Huixin, Chaoxu Liu, Dingkun Zhong, Annual variations in westward auroral electrojet and substorm occurrence rate during solar cycle 23, J. Geophys. Res., 10.1002/2013JA019742, 119, ?-?, 2014.03. |
| 134. | Jianpeng Guo, T. I. Pulkkinen, E. I. Tanskanen, Xueshang Feng, Barbara A. Emery, Huixin Liu, Chaoxu Liu, Dingkun Zhong, Annual variations in westward auroral electrojet and substorm occurrence rate during solar cycle 23, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1002/2013JA019742, 119, 3, 2061-2068, 2014.03, The International Monitor for Auroral Geomagnetic Effects network magnetic measurements during the period 1995-2009 are used to characterize the annual variations in the westward electrojet. The results suggest that the annual variations in different local time sectors are quite different due to the different sources. In the MLT sector 2200-0100, the annual variations with maxima in winter suggest they are caused by the combined effects of the convective electric field and the conductivity associated with particle precipitation. Furthermore, the conductivity seems to play a more important role in the MLT sector similar to 2200-2320, while the convective electric field appears to be more important in the MLT sector similar to 2320-0100. In the MLT sector 0300-0600, the annual variations with maxima in summer suggest they are caused by solar EUV conductivity effect and the equinoctial effect. The solar EUV conductivity effect works by increasing ionospheric conductivity and enhancing the westward electrojet in summer, while the equinoctial effect works by decreasing solar wind-magnetosphere coupling efficiency and weakening the westward electrojet in winter. In the MLT sector 0100-0300, the annual variations are relatively weak and can be attributed to the combined effects of annual variations caused by all the previously mentioned effects. In addition, we find that a significant annual variation in substorm occurrence rate, mainly occurring in the premidnight region, is quite similar to that in the westward electrojet. We suggest that elevated solar wind driving during the winter months contributes to higher substorm occurrence in winter in the Northern Hemisphere.. |
| 135. | Claudia Stolle, Huixin Liu, CHAMP observations of the low latitude ionosphere and thermosphere and comparisons to physical models, AGU monograph: Modeling the Ionosphere-Thermosphere, 201, ?-?, 2014.02. |
| 136. | Nurul Shazana Abdul Hamid, Huixin Liu, Teiji Uozumi, Kiyohumi Yumoto, Equatorial electrojet dependence on solar activity in the Southeast Asia sector, Antarctic Record, 57, 3, 329-337, 2013.12. |
| 137. | Hongru Chen, Liu Huixin, Toshiya Hanada, Storm-time atmospheric density modeling using neural networks and its application in orbit propagation, Adv. in Space Research, 10.1016/j.asr.2013.11.052, 53, 558-567, 2013.12. |
| 138. | Liu Huixin, 児玉 哲哉, 鴨川 仁, 電離圏擾乱における中性大気とプラズマ結合の重要性, 宇宙科学技術連合講演会講演集, 57, 3p, 2013.10. |
| 139. | Nurul Shazana Abdul Hamid, Huixin Liu, Teiji Uozumi, Kiyohumi Yumoto, Brief Study of Equatorial Electrojet and Global Sq Currents At Southeast Asia Region, IEEE International Conference on Space Science and Communication (IconSpace), 1-3 July 2013, 194-197, 2013.07. |
| 140. | Run Shi, Huixin Liu, A. Yoshikawa, Beichen Zhang, Binbin Ni, Coupling of electrons and inertial Alfven waves in the topside ionosphere, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1002/jgra.50355, 118, 6, 2903-2910, 2013.06, A one-dimensional kinetic model is constructed to simulate the electron acceleration by inertial Alfven waves. The electrons are divided into cold and hot electrons and treated separately. Cold components are described by the fluid equation and hot ones by the Vlasov equation, both carrying field-aligned currents. Intense variation of Alfven speed has been introduced by inclusion of cold electrons. The model results show that the exponential decrease of the plasma density plays a key role, which leads to the sharp gradient of both Alfven velocity and electron inertial length. When Alfven waves encounter this sharp gradient at lower altitudes, the electrons accelerated by the waves become super-Alfvenic, and the width of burst structures becomes much wider than the electron inertial length. Consequently, the background electrons carry the oppositely field-aligned current due to plasma oscillation. It is demonstrated that the current carried by the electrons exceeding the wavefront is balanced by the reverse current carried by background electrons. This mechanism can be used to reasonably explain observations of the electron bursts accompanied by little net field-aligned current. Furthermore, our simulation indicates another type of Alfven wave reflection due to mirror force and wave-particle interaction.. |
| 141. | Huixin Liu, H. Jin, Yasunobu Miyoshi, H. Fujiwara, H. Shinagawa, Upper atmosphere response to stratosphere sudden warming: Local time and height dependence simulated by GAIA model, Geophys. Res. Lett., 10.1002/grl.50146, 40, 635-640, 2013.02. |
| 142. | Huixin Liu, T. Hirano, S. Watanabe, Empirical model of the thermospheric mass density based on CHAMP satellite observations, J. Geophys. Res., doi:10.1002/jgra.50144, 118, 843-848, 2013.02. |
| 143. | R. Shi, Huixin Liu, Akimasa Yoshikawa, Beichen Zhang, Binbin Ni, Coupling of electrons and inertial Alfven waves in the topside ionosphere, J. Geophys. Res. , doi:10.1002/jgra.50355, 118, 843-848, 2013.02. |
| 144. | Huixin Liu, Takashi Hirano, Shigeto Watanabe, Empirical model of the thermospheric mass density based on CHAMP satellite observations, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1002/jgra.50144, 118, 2, 843-848, 2013.02, The decadal observations from CHAMP satellite have provided ample information on the Earth's upper thermosphere, reshaping our understandings of the vertical coupling in the atmosphere and near-Earth space. An empirical model of the thermospheric mass density is constructed from these high-resolution observations using the multivariable least-squares fitting method. It describes the density variation with latitude, longitude, height, local time, season, and solar and geomagnetic activity levels within the altitude range of 350-420 km. It represents well prominent thermosphere structures like the equatorial mass density anomaly (EMA) and the wave-4 longitudinal pattern. Furthermore, the empirical model reveals two distinct features. First, the EMA is found to have a clear altitude dependence, with its crests moving equatorward with increasing altitude. Second, the equinoctial asymmetry is found to strongly depend on solar cycle, with its magnitude and phase being strongly regulated by solar activity levels. The equinoctial density maxima occur significantly after the actual equinox dates toward solar minimum, which may signal growing influence from the lower atmosphere forcing. This empirical model provides an instructive tool in exploring thermospheric density structures and dynamics. It can also be easily incorporated into other models to have a more accurate description of the background thermosphere, for both scientific and practical purposes. Citation: Liu, H., T. Hirano, and S. Watanabe (2013), Empirical model of the thermospheric mass density based on CHAMP satellite observation, J. Geophys. Res. Space Physics, 118, 843-848, doi: 10.1002/jgra.50144.. |
| 145. | Y. Yamazaki, A. D. Richmond, Liu Huixin, Kiyohumi Yumoto, Y. Tanaka, Sq current system during stratospheric sudden warming events in 2006 and 2009, J. Geophys. Res. , 10.1029/2012JA018116, 117, 2012.12. |
| 146. | M. H. Jusoh, K. Yumoto, N. S Abdul Hamid, H. Liu, Electromagnetic coupling on solar-terrestrial system: Possible effects on seismic activities, IEEE Antennas and Propagation Society, AP-S International Symposium (Digest), 1160-1163, 2012.12, Solar wind parameters play significant roles in electromagnetic coupling of the Sun - Earth system. By having a long period of observation and analysis of solar activities and its influence on geomagnetic or seismic activities, it is possible to reveal the interconnection between them. In the present paper, we analyzed the earthquake (EQ) events as seismic parameters, which extracted from Advanced National Seismic System (ANSS) database. The different earthquake magnitudes were analyzed with the solar parameters; high-speed solar wind (HSSW) events, and solar wind dynamic pressure (SW Pdyn). All of these analyses were done from year 1964 to 2008, which covers the latest entire solar cycles (cycle number 20 to 23). In the analysis, we propose how the electromagnetic energy can be transferred from the solar wind to the lower ionosphere and finally affected the geomagnetic activities by showing the plots and the statistical analysis on plasma speed event (Vsw), solar wind dynamic pressure (SW Pdyn), solar wind input energy and ring current (Dst) index. The analyzed results show a significant relationship between solar and terrestrial parameters. © 2012 IEICE.. |
| 147. | Yosuke Yamazaki, Arthur D. Richmond, Huixin Liu, Kiyohumi Yumoto, Yoshimasa Tanaka, Sq current system during stratospheric sudden warming events in 2006 and 2009, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2012JA018116, 117, 2012.12, Ionospheric Sq current systems during unusually strong and prolonged stratospheric sudden warming (SSW) events in January 2006 and January 2009 are examined by analyzing ground-magnetometer data for the American and Asian longitude sectors. During these SSW events, a significant decrease and increase of the Sq equivalent current intensity are observed in the Northern and Southern Hemispheres, respectively, along with a reduction in the longitudinal separation between the northern and southern current vortices. Numerical experiments using the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General-Circulation Model show that changes in the solar anti-symmetric (2,3) semidiurnal tide can bring about similar changes in the Sq current system. Citation: Yamazaki, Y., A. D. Richmond, H. Liu, K. Yumoto, and Y. Tanaka (2012), Sq current system during stratospheric sudden warming events in 2006 and 2009, J. Geophys. Res., 117, A12313, doi:10.1029/2012JA018116.. |
| 148. | Jusoh M. H., Kiyohumi Yumoto, Abdul Hamid N. S., Huixin Liu, Electromagnetic Coupling on Solar-Terrestrial System: Possible effects on seismic activities, Proceedings of ISAP2012, 1160-1163, 2012.11. |
| 149. | S. Tulasi Ram, N. Balan, B. Veenadhari, S. Gurubaran, S. Ravindran, T. Tsugawa, Liu Huixin, K. Niranjan, T. Nagatsuma, First observational evidence for opposite zonal electric fields in equatorial E and F region altitudes during a geomagnetic storm period, J. Geophys. Res. , 10.1029/2012JA018045, 118, 2012.09. |
| 150. | S. Tulasi Ram, N. Balan, B. Veenadhari, S. Gurubaran, S. Ravindran, T. Tsugawa, H. Liu, K. Niranjan, T. Nagatsuma, First observational evidence for opposite zonal electric fields in equatorial E and F region altitudes during a geomagnetic storm period, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2012JA018045, 117, 2012.09, The strong westward electrojet and simultaneous upward drift of the equatorial ionospheric peak observed over South-East Asia and Indian equatorial regions during the prolonged Dst minimum phase of an intense geomagnetic storm during 14-15 December 2006 are investigated for the altitudinal variation of zonal electric field polarity using ground based and space-borne observations. The results show first observational evidence for simultaneous existence of daytime westward and eastward zonal electric fields at equatorial E and F region altitudes, respectively, in a wide longitude sector. While the westward electric fields at E region altitudes cause westward electrojet, at the same time, the eastward zonal electric fields at F region altitudes cause the upward drift of the equatorial ionospheric peak and reinforcement of the equatorial ionization anomaly (EIA) even in the topside ionosphere (similar to 660 km). The reversal of the electric fields is found to occur at similar to 280 km height. A clear bifurcation of F region plasma at similar to 280 km is evident in the iso-electron density contours due to these oppositely polarized zonal electric fields, which manifests as an unusually deep cusp between F-1 and F-2 layers on equatorial ionograms. Citation: Tulasi Ram, S., N. Balan, B. Veenadhari, S. Gurubaran, S. Ravindran, T. Tsugawa, H. Liu, K. Niranjan, and T. Nagatsuma (2012), First observational evidence for opposite zonal electric fields in equatorial E and F region altitudes during a geomagnetic storm period, J. Geophys. Res., 117, A09318, doi:10.1029/2012JA018045.. |
| 151. | Y. Miyoshi, H. Fujiwara, H. Jin, H. Shinagawa, Huixin Liu, Numerical simulation of the equatorial wind jet in the thermosphere, J. Geophys. Res. , 10.1029/2011JA017373, 117, 2012.03. |
| 152. | Yasunobu Miyoshi, Hitoshi Fujiwara, Hidekatsu Jin, Hiroyuki Shinagawa, Huixin Liu, Numerical simulation of the equatorial wind jet in the thermosphere, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2011JA017373, 117, 2012.03, We have examined excitation mechanism of the fast jet of the neutral atmosphere along the dip equator in the upper thermosphere. The zonal momentum balance of the neutral atmosphere is estimated using an atmosphere-ionosphere coupled model. The coupled model used in this study is a self-consistent global model of the atmosphere and ionosphere covering the height range from the ground surface to the exobase. It can reproduce the observed equatorial fast jet above 250 km heights. The analysis of the zonal momentum balance reveals that the pressure gradient and ion drag play an important role on the formation of the fast jet near the dip equator. In particular, the fast jet near the equator is closely related with the latitudinal difference of the ion drag force. We also investigate the zonal momentum balance of the longitudinal wave-4 structure of the zonal wind in the fixed local time frame. Furthermore, significant day-to-day variations in the neutral zonal wind and the ion drift near the dip equator are obtained although the solar UV/EUV fluxes and the energy input from the magnetosphere are assumed to be constant during the numerical simulation. This result indicates the importance of the lower atmospheric variability on day-to-day variations in the thermosphere/ionosphere.. |
| 153. | Yasunobu Miyoshi, H. Jin, H. Fujiwara, H. Shinagawa, Huixin Liu, Wave-4 structure of the neutral density in the thermosphere and its relation to atmospheric tides, J. Atmos. Solar-Terres. Phys.,, 10.1016/j.jastp.2011.12.002, 90, 45-51, 2012.01. |
| 154. | Lühr, H., Huixin Liu, J. Park, S. Muller, , New Aspects of the Coupling Between Thermosphere and Ionosphere, with Special regards to CHAMP Mission Results, IAGA Special Sopron Book Series, 10.1007/978-94-007-0326-1_22, 2011.10. |
| 155. | Liu Huixin, M. Yamamoto, E. Doornbos, Equatorial Electrodynamics and Neutral Background in the Asian Sector During the 2009 Stratospheric Sudden Warming, J. Geophys. Res. , 10.1029/2011JA016607, 116, 2011.08. |
| 156. | Huixin Liu, Mamoru Yamamoto, S. Tulasi Ram, Takuya Tsugawa, Yuichi Otsuka, Claudia Stolle, Eelco Doornbos, Kiyohumi Yumoto, Tsutomu Nagatsuma, Equatorial electrodynamics and neutral background in the Asian sector during the 2009 stratospheric sudden warming, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2011JA016607, 116, 2011.08, Using ground observations of total electron content (TEC) and equatorial electrojet (EEJ) in the Asian sector, along with plasma and neutral densities obtained from the CHAMP satellite, we investigate the ionospheric electrodynamics and neutral background in this longitude sector during the major stratospheric sudden warming (SSW) in January 2009. Our analysis reveals the following prominent features. First, the TEC response in tropical regions is strongly latitude dependent, with monotonic depletion at the dip equator but a semidiurnal perturbation at low latitudes. Second, the TEC semidiurnal perturbation possesses a significant hemispheric asymmetry in terms of onset date and magnitude. It starts on the same day as the SSW peak in the Northern Hemisphere but 2 days later in the Southern Hemisphere. Its magnitude is twice as strong in the north than in the south. Third, strong counter electrojet occurs in the afternoon, following the strengthening of the eastward EEJ in the morning. Fourth, semidiurnal perturbation in both TEC and EEJ possesses a phase shift, at a rate of about 0.7 h/day. Comparisons with results reported in the Peruvian sector reveal clear longitude dependence in the amplitude and hemispheric asymmetry of the semidiurnal perturbation. Finally, thermospheric density undergoes similar to 25% decrease at low latitudes in the afternoon local time sector during the SSW, indicating significant cooling effects in the tropical upper thermosphere.. |
| 157. | N. Balan, M. Yamamoto, J. Y. Liu, Y. Otsuka, Huixin Liu, and H. Lühr, New aspects of thermospheric and ionospheric storms revealed by CHAMP, J. Geophys. Res., 10.1029/2010JA016399, 116, 2011.07. |
| 158. | Lühr, H. J. Park, P. Ritter, Huixin Liu, In-situ CHAMP observations of the ionosphere-thermosphere coupling, Space Sci. Rev., 10.1007/s11214-011-9798-4, 2011.07. |
| 159. | Huixin Liu, E. Doornbos, M. Yamamoto, S. T. Ram, Strong thermosphere cooling during the 2009 major statratosphere warming, Geophys. Res. Lett, 10.1029/2011GL047898, 38, 2011.06. |
| 160. | Huixin Liu, M. Yamamoto, Weakening of the mid-latitude summer night anomaly during geomagnetic storms, Earth. Planets and Space, 63, 371-375, 2011.06. |
| 161. | S. Tulasi Ram, M. Yamamoto, Huixin Liu, B. Veenadhari, S. Alex, Comment on “Westward electric field penetration to the dayside equatorial ionosphere during the main phase of the geomagnetic storm on 22 July 2009” by V. Sreeja et al., J. Geophys. Res., 10.1029/2010JA016634, 116, 2011.06. |
| 162. | S. Tulasi Ram, M. Yamamoto, H. Liu, B. Veenadhari, S. Alex, Comment on "Westward electric field penetration to the dayside equatorial ionosphere during the main phase of the geomagnetic storm on 22 July 2009" by V. Sreeja et al, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2011JA016634, 116, 2011.06, Sreeja et al. [2011] have claimed that the "geomagnetic storm that occurred during the period from 21 to 25 July 2009 is anomalous because the storm main phase developed during northward interplanetary magnetic field (IMF)" and "westward electric field penetration to the day-side equatorial ionosphere during the main phase of the storm." However, as discussed subsequently, the so-called "anomalous" feature of geomagnetic storm is ill-fully claimed due to their incorrect IMF B(z) data. Since Sreeja et al. [2011] have made serious claims such as the geomagnetic storm of 21-25 July 2009 is anomalous which would have adverse impact on the future scientific investigations, it is highly necessary to clarify.. |
| 163. | S. V. Thampi, M. Yamamoto, C. Lin, Huixin Liu, Comparison of FORMOSAT‐3/COSMIC radio occultation measurements with radio tomography, Radio Science, 10.1029/2010RS004431, 46, 2011.05. |
| 164. | Y. Miyoshi, H. Fujiwara, H. Jin, H. Shinagawa, Huixin Liu, and K. Terada, Model study on the formation of the equatorial mass density anomaly in the thermosphere, J. Geophys. Res., 10.1029/2010JA016315, 116, 2011.05. |
| 165. | T. Kondo, A. D. Richmond, Huixin Liu, J. Lei, S. Watanabe, On the formation of a fast thermospheric zonal wind at the magnetic dip equator, Geophys. Res. Lett., 10.1029/2011GL047255, 38, 2011.05. |
| 166. | Kondo T., Richmond A. D., Liu H., Lei J., Watanabe S., On the formation of a fast thermospheric zonal wind at the magnetic dip equator, Geophysical Research Letters, 10.1029/2011GL047255, 38, L10101, 2011.05, Simulations with the NCAR Thermosphere - Ionosphere - Electrodynamics General Circulation Model (TIE-GCM) have been carried out to understand the cause of strong thermospheric zonal wind at the magnetic dip equator. The simulations show that the zonal winds blow strongly at the magnetic dip equator instead of at the geographic equator due to the latitude structure of ion drag. The fast winds at the dip equator are seen throughout the altitude between 280 km and 600 km, and the wind above 400 km is mainly accelerated via viscosity. A test simulation without viscosity verifies that the extension of the fast equatorial wind to heights above 400 km is maintained by viscous coupling with the winds at lower altitudes, in spite of there being an ion-drag maximum instead of relative minimum at the dip equator at high altitudes. Basically, viscosity is not so large compared to the pressure gradient and ion drag, but dynamics causes the pressure gradient and ion drag approximately to balance, and viscosity becomes important. The simulation results are consistent with the observations by the DE-2 and CHAMP satellites. Therefore we suggest that the zonal wind velocity in the low latitude region is controlled by ion drag and viscosity.. |
| 167. | C. Stolle, Huixin Liu, V. Truhlík, H. Lühr, P. G. Richards, Solar flux variation of the electron temperature morning overshoot in the equatorial F region, J. Geophys. Res., 10.1029/2010JA016235, 116, 2011.04. |
| 168. | Thampi, S. V., N. Balan, C. Lin, Liu Huixin, M. Yamamoto, Mid-latitude summer nighttime anomaly (MSNA) – observations and model simulations, Ann. Geophys., , 29, 157, 165, 157-165, 2011.04. |
| 169. | Toru Adachi, Masashi Yamaoka, Mamoru Yamamoto, Yuichi Otsuka, Huixin Liu, Chun-Chieh Hsiao, Alfred B. Chen, Rue-Ron Hsu, Midnight latitude-altitude distribution of 630 nm airglow in the Asian sector measured with FORMOSAT-2/ISUAL, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2009JA015147, 115, 2010.09, The Imager for Sprites and Upper Atmospheric Lightning (ISUAL) payload on board the FORMOSAT-2 satellite carried out the first limb imaging observation of 630 nm airglow for the purpose of studying physical processes in the F region ionosphere. For a total of 14 nights in 2006-2008, ISUAL scanned the midnight latitude-altitude distribution of 630 nm airglow in the Asian sector. On two nights of relatively active conditions (Sigma Kp = 26, 30+) we found several bright airglow regions, which were highly variable each night in terms of luminosity and location. In relatively quiet conditions (Sigma Kp = 4-20) near May/June we found two bright regions which were stably located in the midlatitude region of 40 degrees S-10 degrees S (50 degrees S-20 degrees S magnetic latitude (MLAT)) and in the equatorial region of 0 degrees-10 degrees N (10 degrees S-0 degrees MLAT). On one of the quiet nights, FORMOSAT-3/COSMIC and CHAMP simultaneously measured the plasma density in the same region where ISUAL observed airglow. The plasma density data generally show good agreement, suggesting that plasma enhancements were the primary source of these two bright airglow regions. From detailed comparison with past studies we explain that the airglow in the equatorial region was due to the midnight brightness wave produced in association with the midnight temperature maximum, while that in the midlatitude region was due to the typical plasma distribution usually formed in the midnight sector. The fact that the equatorial airglow was much brighter than the midlatitude airglow and was observed on most nights during the campaign period strongly suggests the importance of further studies on the MTM/MBW phenomenology, which is not well reproduced in the current general circulation model.. |
| 170. | Adachi, T., M. Yamaoka, M. Yamamoto, Y. Otsuka, Liu Huixin, C. Hsiao, A. Chen, R. Hsu, Midnight latitude-altitude distribution of 630-nm airglow in the Asian sector measured with Formosat-2/ISUAL, J. Geophys. Res, 10.1029/2009JA015147, 115, A09315, 2010.07. |
| 171. | Thampi, S. V., M. Yamamoto, Liu Huixin, S. Saito, Y. Otsuka, A. K. Patra, Nighttime-like Quasi Periodic echoes induced by a partial solar eclipse, Geophys. Res. Lett., 10.1029/2010GL042855, 37, L09107, 2010.07. |
| 172. | Liu Huixin, Thampi, S. V., M. Yamamoto, Phase reversal of the diurnal cycle in the mid-latitude ionosphere, J. Geophys. Res, 10.1029/2009JA014689, 115, A01305, 2010.06. |
| 173. | Smitha V. Thampi, Mamoru Yamamoto, Huixin Liu, Susumu Saito, Yuichi Otsuka, Amit Kumar Patra, Nighttime-like quasi periodic echoes induced by a partial solar eclipse, GEOPHYSICAL RESEARCH LETTERS, 10.1029/2010GL042855, 37, 2010.05, The first observations of solar eclipse induced mid-latitude plasma irregularities using the middle and upper atmosphere radar (MU radar) at Shigaraki (34.85 degrees N, 136.1 degrees E, 25.0 degrees N geomagnetic) are presented. The observations were done during the partial solar eclipse on 22 July, 2009. The observations show that the sudden withdrawal of solar radiation could deplete the background E-region densities, thereby unmasking the long-lived metallic ions within the strong and patchy Sporadic E-layers. As a result of this, Quasi-Periodic (QP) echoes were generated, which were detected by the MU radar. These echoes resemble the normal post-sunset QP echoes observed over mid-latitudes as revealed by the multi-channel interfereometry imaging. This example shows that over mid-latitudes E-region plasma irregularities can be generated during a partial solar eclipse, revealing a hitherto unobserved aspect of mid-latitude ionospheric responses to eclipses. Citation: Thampi, S. V., M. Yamamoto, H. Liu, S. Saito, Y. Otsuka, and A. K. Patra (2010), Nighttime-like quasi periodic echoes induced by a partial solar eclipse, Geophys. Res. Lett., 37, L09107, doi: 10.1029/2010GL042855.. |
| 174. | Huixin Liu, Smitha V. Thampi, Mamoru Yamamoto, Phase reversal of the diurnal cycle in the midlatitude ionosphere, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2009JA014689, 115, 2010.01, The typical diurnal cycle of the midlatitude F region electron density consists of a midday maximum and a midnight minimum. However, a phase reversal of this diurnal cycle has been found to occur in three distinct regions on the globe. They are the East Asian (EA) region centered around (53 degrees N, 150 degrees E), the Northern Atlantic (NA) region centered around (45 degrees N, 50 degrees W) and the South Pacific (SP) region centered around (60 S, 110 degrees W). The intensively reported Weddell Sea Anomaly falls inside the SP region. The phase reversal occurs during March-August in EA and NA regions, and between August and March in SP region, being most prominent in local summer. Furthermore, this diurnal anomaly is more pronounced at solar minimum than at solar maximum, and more pronounced in SP region than in NA and EA regions, in terms of larger diurnal magnitude and more months it lasts in a year. It is emphasized that the diurnal anomaly consists of not only a nighttime enhancement, but also a concurrent noontime depletion. Hence, midlatitude summer nighttime enhancements reported in previous studies are just part of this reversed diurnal cycle. The cause for the phase reversal involves several interplaying physical processes. Among these, the neutral wind combined with the geomagnetic field configuration plays a pivotal role. It generates a one-wave longitudinal pattern at southern middle latitudes and a two-wave pattern at northern middle latitudes, whose wave peaks correspond to the center of the SP, EA, and NA regions, respectively. The seasonal variation of neutral winds and downward motion of the ionization induced by thermal contraction of the ionosphere at sunset may largely control the occurring local time of the nighttime density enhancement and how long it persists in different months. The phase reversal occurs as a result of close ion-neutral coupling. It is further noted that winter anomaly in the EA, NA, and SP regions is very weak or missing.. |
| 175. | Smitha V. Thampi, Charles Lin, Huixin Liu, Mamoru Yamamoto, First tomographic observations of the Midlatitude Summer Nighttime Anomaly over Japan, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2009JA014439, 114, 2009.10, Recently, a chain of digital beacon receivers has been established over Japan, mainly for the tomographic imaging of the ionosphere. These receivers are installed at Shionomisaki (33.45 degrees N, 135.8 degrees E), Shigaraki (34.85 degrees N, 136.1 degrees E), and Fukui (36.06 degrees N, 136 degrees E), which continuously track the Low Earth Orbiting Satellites (LEOS), and the simultaneous line-of-sight Total Electron Content (TEC) data are used for tomographic reconstruction. In the images obtained during July 2008, it is seen that the nighttime electron densities exceed the daytime values on almost all days over latitudes > 33-34 degrees N. On several days, these northern latitudes show enhanced electron densities compared to the low-latitude region during nighttime. These are the prominent features of the "Midlatitude Summer Nighttime Anomaly (MSNA)'' that is recently observed in the northern hemisphere and is considered similar to the nighttime Weddell Sea Anomaly (WSA). This is the first study of the MSNA using tomographic technique and found its significant day-to-day variability. The ionosonde data from Wakkanai (45.4 degrees N, 141.7 degrees E), ground-based GPS TEC observations using the GEONET, CHAMP in situ electron density measurements, and Formosat3/COSMIC (F3/C) occultation measurements are also used to confirm the presence of MSNA over this region and to examine its variability. It is seen that, in general, during the local summer period, electron density over the northern latitudes is highest at similar to 2000-2100 LT and the latitudinal enhancement in electron density also begins to appear around the same time, which continues to exist even at later hours.. |
| 176. | Thampi, S. V., C. Lin, Liu Huixin, M. Yamamoto, First Tomographic Observations of the Mid-latitude Summer Nighttime Anomaly (MSNA) over Japan, J. Geophys. Res. , 10.1029/2009JA014439, 114, A10318, 2009.07. |
| 177. | Liu Huixin, M. Yamamoto, H. Luehr, Wave-4 pattern of the equatorial mass density anomaly- A thermospheric signature of tropical deep convection, Geophys. Res. Lett., 10.1029/2009GL039865, 36, L18104, 2009.06. |
| 178. | Liu Huixin, H. Luehr, S. Watanabe, A solar terminator wave in thermospheric wind and density simultaneously observed by CHAMP, Geophys. Res. Lett., 10.1029/2009GL038165, 36, L10109, 2009.05. |
| 179. | Liu Huixin, S. Watanabe, T. Kondo, Fast thermospheric wind jet at the Earth's dip equator, Geophys. Res. Lett., 10.1029/2009GL037377, 36, L08103, 2009.03. |
| 180. | Huixin Liu, Shigeto Watanabe, Seasonal variation of the longitudinal structure of the equatorial ionosphere: Does it reflect tidal influences from below?, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2008JA013027, 113, A8, 2008.08, We have examined the longitudinal structure of the equatorial ionosphere at 400-km altitude in the noon and postsunset local time sectors in different seasons using 6 years of F-region plasma density observations from the CHAMP satellite. A four-peak wave structure is observed in both local time sectors. In the noon sector at a fixed solar flux level, this structure is observed to be most prominent around September equinox and weakest around December solstice. This seasonal dependence agrees well with that of the nonmigrating diurnal tides DE3, hence supporting a close coupling between the ionosphere and the mesosphere-lower thermosphere possibly via the DE3 tidal modulation of the E-layer dynamo. In the postsunset sector, however, such agreement cannot be claimed. In this sector, although the four-peak structure can be observed in all seasons at moderate and high solar flux levels, its seasonal dependence does not follow that of the DE3 tides. This structure becomes indiscernible near solstices at low solar flux levels. Furthermore, the postsunset four-peak wave structure exhibits larger amplitude than that during daytime, hence indicating that it is more likely an amplified feature rather than a remnant of the daytime structure. The prereversal enhancement is speculated to be a possible candidate to cause this amplification.. |
| 181. | Liu Huixin, S. Watanabe, Seasonal variation in the longitudinal structure of the equatorial ionosphere: does it reflect tidal influences from below? , J. Geophys. Res. , 10.1029/2008JA013027, 113, A08315, 2008.01. |
| 182. | Huixin Liu, Claudia Stolle, Matthias Foerster, Shigeto Watanabe, Solar activity dependence of the electron density in the equatorial anomaly regions observed by CHAMP, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2007JA012616, 112, A11, 2007.11, We have investigated the solar activity dependence of the electron density at equatorial and low latitudes using 6 years ( a) of measurements between 1 August 2000 and 1 August 2006 from CHAMP and compared it with the international reference ionosphere ( IRI) model. The solar activity dependence observed by CHAMP at 400 km altitude exhibits significant variation with latitude, season, and local time. First, the electron density in the crest regions of the equatorial ionization anomaly ( EIA) grows roughly linearly from solar minimum to solar maximum, with a higher growth rate than that in the EIA trough region. Second, the solar activity dependence in the EIA crest regions varies strongly with season. The growth rate of the electron density with increasing solar activity around equinoxes is about 1.5 to 2 times greater than that near solstices. Third, the solar activity dependence of the EIA structure varies significantly with local time. In the noon sector the crest-to-trough ratio ( CTR) obtained at 400 km altitude varies within only a small range between 1.14 and 1.43 from solar minimum to solar maximum. In the postsunset local time sector, however, the CTR grows remarkably with solar activity level, reaching values of above 3.9 at solar maximum. These differences are attributed to the different solar activity dependence of the vertical plasma drift in corresponding local time sectors. The IRI model was found to reproduce the equatorial electron density well near 400 km in the noon sector at all solar activity levels. However, it significantly overestimates it in the postsunset to premidnight sector at high solar activity levels. The major cause for this overestimation has been found to be the IRI's inadequate representation of the F-2 layer maximum height ( h(m)F(2)) in this sector, while the IRI's lack of equatorial spread F seems to play only a minor role.. |
| 183. | Huixin Liu, Hermann Luehr, Shigeto Watanabe, Wolfgang Koehler, C. Manoj, Contrasting behavior of the thermosphere and ionosphere in response to the 28 October 2003 solar flare, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2007JA012313, 112, A7, 2007.07, [1] We examined the thermospheric and ionospheric responses to the solar flare on 28 October 2003, utilizing simultaneous observations of the electron and neutral density from the CHAMP satellite. Rapid thermospheric response within a few minutes was observed. In addition, the neutral and plasma perturbations contrasted each other remarkably. First, their temporal development differed. Though started nearly simultaneously, the plasma perturbation developed much faster and to a larger amplitude than its neutral counterpart. Second, their latitudinal distributions differed. At the initial stage of the response, the neutral density was enhanced by 20% almost homogeneously at all latitudes below 50 degrees N/S. In comparison, the plasma disturbance exhibited a distinctive latitudinal structure, with largest density enhancements of 68% at the dip equator, moderate increase of similar to 20% at midlatitudes, and depression up to 35% around 15 degrees N/S. This suggests a decoupling between the neutral and plasma disturbances during this stage. The plasma-neutral coupling via ion drag was found to become important about 2 - 3 hours after the flare bursts. Another interesting feature is that the equatorial ionization anomaly was significantly weakened during the flare. The observations demonstrated that electrodynamics related to the equatorial fountain dominated the photochemistry in controlling the flare-induced plasma density disturbances on 28 October 2003. This differs considerably from the nearly linear cos(SZA) dependence of flare-induced total electron content enhancements.. |
| 184. | Liu Huixin, H. Luehr, S. Watanabe, W. Koehler, M. Manoj, Contrasting behavior of the thermosphere and ionosphere to the Oct. 28, 2003 solar flare, J. Geophys. Res., 10.1029/2007JA012313, 112, A07305, 2007.05. |
| 185. | Liu Huixin, H. Luehr, S. Watanabe, V. Henize, W. Koehler, P. Visser, Zonal winds in the equatorial upper thermosphere: Decomposing the solar flux, geomagnetic activity, and seasonal dependencies, J. Geophys. Res., 10.1029/2005JA011415, 111, A07307, 2007.05. |
| 186. | Huixin Liu, Hermann Luehr, Shigeto Watanabe, Climatology of the equatorial thermospheric mass density anomaly, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2006JA012199, 112, A5, 2007.05, The equatorial anomaly is an interesting and important feature of the Earth's thermosphere-ionosphere coupling in tropical regions. It is an anomalous latitudinal distribution found in both the ionized and unionized part of the atmosphere. Its equinox configuration consists of a minimum near the dip equator flanked by two maxima on both sides. The ionospheric side of this anomaly, often referred to as the equatorial ionization anomaly ( EIA), has long been recognized since the 1930s. However, its thermospheric counterpart was only to be glimpsed by the Dynamic Explorer 2 satellite in the 1970s. A global picture of it has been rather recently revealed by the CHAMP satellite in 2005. In this paper we complement previous studies by investigating the climatology of the equatorial mass anomaly ( EMA) in the thermosphere using 4 years of CHAMP measurements. Our analysis has revealed strong variation of the EMA with season and solar flux level. The EMA structure is most prominent around equinox, with a crest-to-trough ratio about 1.05 for F10.7 = 150. Near solstices, it is asymmetric about the dip equator. The density crest attains maximum 1-2 hours earlier and reaches higher values in the summer hemisphere than in the winter hemisphere. The density in EMA regions varies semiannually, with maxima near equinoxes. The latitudinal locations of the EMA crests undergo a seasonal variation, obviously following the movement of the subsolar point. The EMA structure has also been found to become more pronounced at higher solar flux levels. Both the location and magnitude of the EMA crests closely follow those of the EIA in corresponding seasons and solar flux levels, hence demonstrating strong plasma-neutral interaction. Furthermore, two seasonal asymmetries clearly present in the globally averaged density, with the density in March/December being similar to 15-20% higher than that in September/June.. |
| 187. | Liu Huixin, C. Claudia, M. Forster, S. Watanabe, Solar activity dependence of the electron density at 400 km at equatorial and low latitudes observed by CHAMP, J. Geophys. Res., 10.1029/2007JA012616, 112, A11311, 2007.03. |
| 188. | Liu Huixin, C. Claudia, S. Watanabe, T. Abe, D. Cooke, Evaluation of the IRI Model Using CHAMP Observations in Polar and Equatorial Regions, Adv. in Space. Res., , 39, 904-909, 2007.03. |
| 189. | 佐藤 創我, Liu Huixin, 渡部 重十, 極域電離圏上部におけるイオン上昇流の観測, 北海道大学地球物理学研究報告, 10.14943/gbhu.70.13, 70, 13-25, 2007.03, Ion upflow has been investigated by use of ESR (EISCAT Svalbard Radar), SuperDARN,ACE satellite and CHAMP satellite. The field-aligned ion upflows were observed by ESR,which occurred in night-time between 16 and 17, April 2002, and 19 June 2004. However,ESR didn't show remarkable increase of electron density, electron temperature and iontemperature, which are generated by auroral particle precipitation or frictional heating.The Solar wind parameters were obtained by ACE satellite. SuperDARN showed variationof convection electric field depending on By component of Interplanetary Magnetic Field.CHAMP satellite observed also variations of neutral density, neutral wind, ion density andelectron temperature along the satellite orbits. At the time, ESR was in the polar cap region.Our analyses may suggest that the ion upflow observed by ESR was generated in the upwindregion of plasma convection in the high-latitude ionosphere and was moving to ESR stationby the convection.. |
| 190. | Liu Huixin, H. Luehr, S. Watanabe, Climatology of the Equatorial Thermospheric Mass Density Anomaly, J. Geophys. Res., 10.1029/2006JA012199, 112, A05305, 2007.01. |
| 191. | Huixin Liu, Hermann Luehr, Shigeto Watanabe, Wolfgang Koehler, Vance Henize, Pieter Visser, Zonal winds in the equatorial upper thermosphere: Decomposing the solar flux, geomagnetic activity, and seasonal dependencies, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2005JA011415, 111, A7, 2006.07, [ 1] Using 3 years ( 2002 - 2004), over 16,400 orbits of measurements from the accelerometer on board the CHAMP satellite, we have studied the climatology of the equatorial zonal wind in the upper thermosphere. Several main features are noticed. The most prominent one is that the solar flux significantly influences both the daytime and nighttime winds. It overrides the geomagnetic activity effect, which is found to be rather limited to the nightside. An elevation of the solar flux level from F10.7 approximate to 100 x 10(-22) W m(-2) Hz(-1) to F10.7 approximate to 190 x 10(-22) Wm(-2) Hz(-1) produces an eastward disturbance wind up to similar to 110 m s(-1). This consequently enhances the nighttime eastward wind but suppresses the daytime westward wind. A seasonal variation with weaker wind ( by over 50 m s(-1) at night) around June solstice than in other seasons has been observed regardless of solar flux and geomagnetic activity levels. The zonal wind is eastward throughout the night except around June solstice, where it ebbs to almost zero or turns even westward in the postmidnight sector at low solar flux level. The daytime wind is found to be generally more stable than the nighttime wind, particularly unresponsive to geomagnetic activities. Predictions from the Horizontal Wind Model find good agreement with the CHAMP-observed wind at high solar flux levels during nighttime. At low solar flux levels, however, the model strongly underestimates the westward wind during morning hours by 50 - 120 m s(-1) depending on season. The major difference between the HWM-predicted and the CHAMP-observed wind is seen in the phase of its diurnal variation. The CHAMP-observed wind turns eastward around 1200 - 1300 MLT instead of 1600 - 1700 MLT predicted by the model. Comparisons with ground FPI observations and the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) predictions show that the solar flux effect obtained from CHAMP is consistent with that modeled by TIEGCM. The solar flux dependence of zonal wind found here together with that of the zonal ion drift found in previous studies reflect the relative importance of the E- and F-region wind dynamo in the thermosphere-ionosphere coupling process. Furthermore, these wind measurements indicate that the Earth's atmosphere superrotates. The average superrotation speed amounts to about 22 m s(-1) for a solar flux level of F10.7 approximate to 100 x 10(-22) W m(-2) Hz(-1) but increases to 63 m s(-1) for F10.7 approximate to 190 x 10(-22) W m(-2) Hz(-1). Finally, the wind behavior presented in this study is longitudinally averaged and may differ from wind measurements at a certain longitude.. |
| 192. | Liu Huixin, H. Luehr, Strong disturbance of the upper thermospheric density due to magnetic storms: CHAMP observations, J. Geophys. Res., 10.1029/2004JA010908, 110, A09S29, 2005.10. |
| 193. | Liu Huixin, H. Luehr, V. Henize, W. Koehler, Global distribution of the thermospheric total mass density derived from CHAMP, J. Geophys. Res., 10.1029/2004JA010741, 110, A04301, 2005.05. |
| 194. | Liu Huixin, G. Lu, Velocity shear-related ion upflows in the low-altitude ionosphere, Ann. Geophysics., 22, 1149-1153, 2004.10. |
| 195. | SY Ma, HX Liu, K Schlegel, A comparative study of magnetic storm effects on the ionosphere in the polar cap and auroal oval - F-region negative storm, CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION, 45, 2, 160-169, 2002.03, With coordinated EISCAT and ESR radar data, ionospheric storm in both the dayside polar cap and the auroral oval during the major magnetic storm of May 15, 1997 is studied, focusing on the F-region negative storm. It is found that in both the polar cap and the auroral zone a F1-like peak of ionization appeared at 190km height during the main and recovery phases of the storm; while the normal F2 peak disappeared and great depletions of electron density occurred. In contrast, variations of ion temperature are very different in the two regions, with little change in polar cap while strong enhancement in auroral oval, implying a difference in key mechanisms for the negative storms in the two regions. The increase of O+ ion loss rate through chemical reaction due to Joule heating and enhancement of ion temperature resulted from strong electric field played a crucial role in the auroral zone. The plasma transport process, however, especially the long-lasting large ion upflow, is of great importance-in the polar cap. In addition, large F-region electron density depletion associated with null Joule heating and ion temperature enhancement is observed by EISCAT radar in the transient region of the two cells of plasma convection, which is caused by strong field-aligned O+ ion outflow when the radar passing through probably under the polar cleft ion fountain region.. |
| 196. | SY Ma, P Liu, HX Liu, K Schlegel, JS Xu, A reversed plasma convection flow in the polar ionosphere observed with EISCAT radar, CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION, 44, 4, 446-453, 2001.07, An abnormal anti-sunward intense flow of plasma convection is observed by EISCAT radar in the high-latitude ionosphere near the polar cap boundary. It occurred at morning sector of MLT under conditions of southward IMF B-z during the recovery phase of a moderate magnetic storm. A synthetic analysis of radar data and in-situ satellite observations is made in combination with a tracing of magnetic field lines by means of magnetospheric field model on this event. It is evidently indicated that the abnormal reversed westward flow of plasma convection and the features of the plasma structure and property are probably the ionospheric signatures of magnetic reconnection taking place at the dayside magnetopause.. |
| 197. | Liu Huixin, S. Y. Ma, K. Schlegel, Diurnal, seasonal, and geomagnetic variations of large field-aligned ion upflows in the high-latitude ionospheric F region, J. Geophys. Res, 106, 24,651-24,662, 2001.06. |
| 198. | Liu Huixin, K. Schlegel, S. Y. Ma, Combined ESR and EISCAT observations of the dayside polar cap and auroral oval during the May 15, 1997 storm, Ann. Geophysics., 18, 1067-1072, 2000.10. |
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九大関連コンテンツ
QIR 九州大学学術情報リポジトリ システム情報科学研究院
理学部・理学研究院
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