Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Kaoru Ichikawa Last modified date:2020.06.05

Associate Professor / Interdisciplinary Graduate School of Engineering Sciences, Department of Earth System Science and Technology, Environmental Metrology / Division of Earth Environment Dynamics / Research Institute for Applied Mechanics

1. Xifeng Wang, Kaoru Ichikawa and Dongni Wei, Coastal Waveform Retracking in the Slick-Rich Sulawesi Sea of Indonesia, Based on Variable Footprint Size with Homogeneous Sea Surface Roughness, Remote Sensing, 10.3390/rs11111274, 11, 11, 1274, 2019.05, [URL], Waveforms of radar altimeters are often corrupted due to heterogeneous sea surface roughness within footprints, such as slicks. In past studies, subwaveform retrackers such as the adaptive leading edge subwaveform retracker (ALES) which use only a section of the waveform have been proposed. However, it is difficult to choose a reasonable estimation window from an individual waveform. In the present study, a post-processed subwaveform retracker is proposed which identifies the waveforms of surrounding along-track points. The size of the estimation window is variable and is determined to keep the sea surface roughness within the corresponding footprint homogeneous. The method was applied to seven years of 20 Hz Jason-2 altimeter data over the slick-rich Sulawesi Sea of Indonesia and compared with ALES and sensor geophysical data record (SGDR) products. The standard deviation of the sea surface dynamic heights was around 0.13 m, even without spatial smoothing or some geophysical corrections. This is only 75% and 25% of the ALES and SGDR results, respectively. Moreover, all retrievals of the range, SWH, and sigma0 include less outliers than the other products. These results indicate that the variable estimation windows determined in the present study can adapt well to the variation of sea surface roughness..
2. Kaoru Ichikawa, Takuji Ebinuma, Masanori Konda, Kei Yufu, Low-Cost GNSS-R Altimetry on a UAV for Water-Level Measurements at Arbitrary Times and Locations, Sensors (Basel, Switzerland), 10.3390/s19050998, 19, 5, 2019.02, Together with direct Global Navigation Satellite System (GNSS) signals, the signals reflected at the water surface can be received by an unmanned aerial vehicle (UAV). From the range difference between two GNSS signal paths, the height of the UAV above the water level can be geometrically estimated using the weighted least squares method, called GNSS reflectometry (GNSS-R) altimetry. Experimental low-cost GNSS-R altimetry flights with a UAV were conducted at the coast of Lake Biwa, Japan. Although the height estimated by the GNSS-R altimeter included large short-term noises up to 8 m amplitude, it agreed well with the UAV altitude measured by the post-processed kinematic positioning. By selecting better weight functions in the least square method and using sufficient temporal averaging, the GNSS-R altimetry achieved accuracy in the order of 0.01 m if a sufficient number of GNSS satellites with high elevation angles were available. The dependency of the results on the weight functions is also discussed..
3. Keisuke Ariyoshi, Shuhei Nishida, Yuya Machida, Takeshi Iinuma, Kan Aoike, Hiroshi Uchida, Akira Nagano, Takuya Hasegawa, Mikiko Fujita, Toru Miyama, Yasumasa Miyazawa, Akira Kuwano-Yoshida, Masahide Wakita, Akiko To, Tatsu Kuwatani, Kaoru Ichikawa, A total station plan combined with "D/V Chikyu" and DONET:Simultaneous observation from seafloor to atmosphere, 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans, OCEANS - Kobe 2018 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans, OCEANS - Kobe 2018, 10.1109/OCEANSKOBE.2018.8559382, 2018.12, DONET (Dense Oceanfloor Network system for Earthquakes and Tsunamis) has been developed and installed around Nankai Trough, which is motivated by the 2004 Sumatra-Andaman Earthquake. DONET contains pressure gauges as well as seismometers, which is expected to detect crustal deformations driven by peeling off subduction plate coupling process. From our simulation results, leveling changes are different sense among at the DONET points even in the same science node. On the other hand, oceanic fluctuations such as melting ice masses through the global warming has so large scale as to cause ocean bottom pressure change coherently for all of DONET points especially in the same node. This difference suggests the possibility of extracting crustal deformations component from ocean bottom pressure data by differential of stacking data. However, this operation cannot be applied to local-scale fluctuations related to ocean mesoscale eddies and current fluctuations, which affect ocean bottom pressure through water density changes in the water column (from the sea surface to the bottom). Recently, Kuroshio current path has been changed drastically, which significantly affect ocean bottom pressures at DONET station points. Therefore, we need integral analysis by combining seismology, ocean physics and tsunami engineering so as to decompose into crustal deformation, oceanic fluctuations and instrumental drift, which will bring about high precision data enough to find geophysical phenomena. Since DONET has been and will be connected to long-term borehole observatories constructed in the Nankai Trough under the Integrated Ocean Drilling Program (IODP) by using the deep-sea drilling vessel Chikyu, we have to discuss the best way to do simultaneous observation from seafloor to atmosphere by taking advantage of this chance..
4. Ichikawa K., Yoshikawa Y., Morimoto A., Fukudom K., Yoon JH., Complementary Remote Sensing Observations of the Tsushima Warm Current Patterns, Remote Sensing of the Asian Seas, 10.1007/978-3-319-94067-0_10, 191-204, Barale V., Gade M. (eds), Springer, Cham, ISBN 978-3-319-94067-0, 2018.09, [URL], When monitoring exchanges between adjacent marginal seas, measurements of the volume transport through connecting straits are essential. In such cases, acoustic Doppler current profilers (ADCPs) mounted at the bottom of ferries that regularly cross such straits can provide useful platforms for directly monitoring strait currents. However, since their observations would naturally be confined to each ferry's set route, it would be impossible for them to observe all relevant current patterns. In addition, a ship-mounted ADCP is very expensive to install, maintain, and (when necessary) remove. In this chapter, we will describe alternative indirect remote sensing techniques that can be used to observe surface velocities in the Korea Strait between Japan and Korea. One such technique involves a high-frequency (HF) ocean radar system that can provide synoptic views of the surface velocity field with high resolutions in both space and time, even though additional processes are required to separate the geostrophic ocean currents from the ageostrophic tidal and wind-driven currents. Alternatively, slopes of the sea surface dynamic height (SSDH) can provide a geostrophic component of the surface velocity. Unfortunately, the satellite altimeters that are most commonly used to measure the SSDH field in open oceans are unsuitable for use in narrow straits. Instead, the use of global navigation satellite systems (GNSS) is showing promise as a way to obtain the coastal SSDH, even though proper spatial smoothing processes are still required..
5. Ichikawa K., Remote Sensing of the Kuroshio Current System, Remote Sensing of the Asian Seas, 10.1007/978-3-319-94067-0_10, 205-220, Barale V., Gade M. (eds), Springer, Cham, ISBN 978-3-319-94067-0, 2018.09, [URL], Variations of the Kuroshio Current System, which is the western boundary current of the North Pacific, influence both large-scale climate changes and regional waters.
Satellite altimeters have been widely used to monitor various aspects of the Kuroshio, such as its position and volume transport.
Although both meanders of the Kuroshio axis and isolated mesoscale eddies result in similar mesoscale temporal anomaly, they can be distinguished when the mean sea surface dynamic height is retrieved, which cannot be obtained by altimetry data alone. This enables us to describe the shedding and merging of offshore mesoscale eddies and the development of the stable large meander south of Japan.
Spatial and temporal resolutions of satellite altimetry data are, however, not sufficient to describe fast-moving small-scale variations of the Kuroshio itself. The high-resolution surface velocity field around the Kuroshio can be directly obtained by high-frequency (HF) ocean radars, which can provide thorough descriptions of the Kuroshio in terms of variations of the maximum speed of the Kuroshio and the displacement of its axis position. In addition, short-term variations of the Kuroshio, such as responses to extraordinary winds of a typhoon, can be studied quantitatively..
6. XiFeng Wang, Kaoru Ichikawa, Coastal Waveform Retracking for Jason-2 Altimeter Data Based on Along-Track Echograms around the Tsushima Islands in Japan, Remote Sensing, 10.3390/rs9070762, 2017, 9, 7, 2017.07, Although the Brown mathematical model is the standard model for waveform retracking
over open oceans, due to heterogeneous surface reflections within altimeter footprints, coastal
waveforms usually deviate from open ocean waveform shapes and thus cannot be directly interpreted
by the Brown model. Generally, the two primary sources of heterogeneous surface reflections are land
surfaces and bright targets such as calm surface water. The former reduces echo power, while the
latter often produces particularly strong echoes. In previous studies, sub-waveform retrackers, which
use waveform samples collected from around leading edges in order to avoid trailing edge noise,
have been recommended for coastal waveform retracking. In the present study, the peaky-type noise
caused by fixed-point bright targets is explicitly detected and masked using the parabolic signature in
the sequential along-track waveforms (or, azimuth-range echograms). Moreover, the power deficit of
waveform trailing edges caused by weak land reflections is compensated for by estimating the ratio
of sea surface area within each annular footprint in order to produce pseudo-homogeneous reflected
waveforms suitable for the Brown model. Using this method, altimeter waveforms measured over
the Tsushima Islands in Japan by the Ocean Surface Topography Mission (OSTM)/Jason-2 satellite
are retracked. Our results show that both the correlation coefficient and root mean square difference
between the derived sea surface height anomalies and tide gauge records retain similar values
at the open ocean (0.9 and 20 cm) level, even in areas approaching 3 km from coastlines, which
is considerably improved from the 10 km correlation coefficient limit of the conventional MLE4
retracker and the 7 km sub-waveform ALES retracker limit. These values, however, depend on the
topography of the study areas because the approach distance limit increases (decreases) in areas with
complicated (straight) coastlines..
7. XiFeng Wang, Kaoru Ichikawa, Effect of High-Frequency sea waves on wave period retrieval from radar altimeter and buoy data, Remote Sensing, doi:10.3390/rs8090764, 8, 764, 2016.09, [URL], Wave periods estimated from satellite altimetry data behave differently from those calculated from buoy data, especially in low-wind conditions. In this paper, the geometric mean wave period Ta is calculated from buoy data, rather than the commonly used zero-crossing wave period Tz. The geometric mean wave period uses the fourth moment of the wave frequency spectrum and is related to the mean-square slope of the sea surface measured using altimeters. The values of Ta obtained from buoys and altimeters agree well (root mean square difference: 0.2 s) only when the contribution of high-frequency sea waves is estimated by a wavenumber spectral model to complement the buoy data, because a buoy cannot obtain data from waves having wavelengths that are shorter than the characteristic dimension of the buoy..
8. Takuji Ebinuma, Kaoru Ichikawa, Takuji Waseda, Yukihito Kitazawa, Hitoshi Tamura, Osamu Isoguchi, Hiroyuki Tomita, GNSS Reflectometry and Multi-Sensor Ocean Wave and Wind Monitoring at Hiratsuka Marine Observation Tower, Proceedings of the International Symposium on GNSS 2015, 584-587, 2016.05.
9. HW Chen, CT Liu, Takeshi Matsuno, Kaoru Ichikawa, 福留 研一, Yih Yang, DJ Doong, WL Tsai, Temopral variations of volume transport through the Taiwan Strait, as identified by three-year measurements, Continental Shelf Research, 10.1016/j.csr.2015.12.010, 114, 41-53, 2016.02.
10. SM Verlamov, X Guo, T Miyama, Kaoru Ichikawa, T Waseda, Y Miyazawa, M2 baroclinic tide variability modulated by the ocean circulation south of Japan, Journal of Geophysical Research, 10.1002/2015JC010739, 120, C5, 2015.05.
11. Remote Sensing Observations for Next-Generation Coastal Numerical Models.
12. Akira Nagano, Kaoru Ichikawa, Hiroshio Ichikawa, Masanori Konda, Kiyoshi Murakami, Volume transports proceeding to the Kuroshio Extension region and recirculating in the Shikoku Basin, Journal of Oceanography, 10.1007/s10872-013-0173-9, 69, 3, 285-293, 2013.05, [URL], The volume transport of the Kuroshio, the western boundary current of the North Pacific subtropical gyre, varies vigorously due to merging of disturbances propagating from the entire North Pacific. Taking into account the recirculation in the Shikoku Basin by the zonal observation line at 30「ェN to the west of the Izu-Ogasawara Ridge, we estimated the volume transport in the top 1000 m layer toward the Kuroshio Extension region. The volume transport of the local recirculation gyre in the Shikoku Basin increases associated with the westward extension of the gyre, particularly in the period of the large meandering path of the Kuroshio south of Japan. Meanwhile, most of the transport variations toward the Kuroshio Extension region correspond to those of the Kuroshio transport on the continental slope south of Japan, which vary independently of those of the recirculation gyre..
13. Akira Nagano, Kaoru Ichikawa, Hiroshi Ichikawa, Yasushi Yoshikawa, Kiyoshi Murakami, Large ageostrophic currents in the abyssal layer southeast of Kyushu, Japan, by direct measurement of LADCP, Journal of Oceanography, doi:10.1007/s10872-013-0170-z, 69, 2, 259-268, 2013.04, With full-depth LADCP velocity data collected in a wide area southeast of Kyushu, Japan, large velocity currents, occasionally exceeding 15 cm s-1, were observed in a thick, 500.1,500 m, near-homogeneous density layer below approximately 3,000 m depth around the steep topographies. The currents were found not to flow along the topographic contours, and to be strongly ageostrophic.
The directions of the bottom-layer currents are rather related with phase of the semi-diurnal tides, suggesting deeply intruded internal tides generated at the steep topographies..
14. Akira Nagano, Kaoru Ichikawa, Hiroshi Ichikawa, Yasushi Yoshikawa, Masanori Konda, Kiyoshi Murakami, Subsurface current structures east of Amami-Oshima Island based on LADCP observation, Journal of Advanced Marine Science and Technology Society, 18, 2, 19-26, 2013.03, The current system east of the Ryukyu Islands has been called the Ryukyu Current System (RCS) to express its possibly different origins and features. In this paper, we presented a new feature on the vertical structure of the current system by using lowered acoustic Doppler current profiler (LADCP) data in early October 2005; a southwestward countercurrent was demonstrated to flow near the eastern slope of the Nansei-Shoto (Ryukyu Islands) Ridge in a layer deeper than the northeastward current core of the RCS. This supports the existence of the countercurrent suggested by Nagano et al. (2009). The maximum speed of the countercurrent was measured to be 25 cm s.1 at a depth of approximately 600 m..
15. Ichikawa Kaoru, Wen Chang Yang, Akihiko Morimoto, Yoshikawa Yutaka, Shigeo Sugitani, Wen-Shan Chiang, Jian-Wu Lai, En Yu Liang, Cho-Teng Liu, Chang-Wei Lee, Kei Yufu, Moeto Kyushima, Satoshi Fujii, Senjyu Tomoharu, Yoshihiko Ide, Preliminary results of the Japan-Taiwan joint survey on combining ocean radar data in the Kuroshio upstream region, Ocean Science Journal, 10.1007/s12601-013-0011-4, 48, 1, 141-148, 2013.03, [URL], Japanese and Taiwanese institutes have collaborated to obtain ocean radar data with significantly increased coverage in the upstream Kuroshio region. An international joint survey was conducted in June 2012, in which intensive in situ observations were performed within the radar coverage. Details of the joint survey are presented in this paper with brief descriptions of preliminary results on the surface and subsurface currents near and within the Kuroshio..
16. P. Cipollini, J. Benveniste, L. Miller, N. Picot, R. Scharroo, T. Sturb, D. Vandemark, S. Vignudelli, S. Zoffoli, O. Andersen, L. Bao, F. Birol, E. Coelho, X. Deng, W. Emery, L. Fenoglio, J. Fernandes, J. Gomez-Enri, D. Griffin, G. Han, J. Hausman, Kaoru Ichikawa, A. Kostianoy, V. Kourafalou, S. Labroue, R. Ray, M. Saraceno, W. Smith, P. Thibaut, J. Wilkin, S. Yenamandra, Conquering the Coastal Zone: A new frontier for satellite altimetry, "Proceedings of '20 years of Progress in Radar Altimetry', Venice Italy", (ed. L. Ouwehand), 10.5270/esa.sp-710.altimetry2012, ESA SP-710, 2013.02.
17. Kaoru Ichikawa, Akihiko Morimoto, Kenichi Fukudome, Jong-Hwan Yoon, Yutaka Yoshikawa, Coastal Sea Surface Dynamic Height Monitoring by GPS Mounted on a Ferry Boat, "Proceedings of '20 years of Progress in Radar Altimetry', Venice Italy", (ed. L. Ouwehand), 10.5270/esa.sp-710.altimetry2012, ESA SP-710, 2013.02.
18. Ichikawa Kaoru, Tatsuya Yamauchi, Yoshikawa Yutaka, Akihiko Morimoto, Shigeo Sugitani, Seasonal variation of the deflection angle of the wind-driven surface flow estimated from altimeters and long-ragne ocean radars, 2011 Ocean Surface Topography Science Team Meeting Abstracts, 149, 2011.10, Ageostrophic velocity component is estimated by subtracting the geostrophic velocity determined from the along-track Jason-1/2 data from the surface velocity observed by long-range ocean radars in the upstream region of the Kuroshio operated by NICT, Japan. Assuming that the ageostrophic component is dominated by the wind-driven surface flow, the speed factor, or the ratio of the speed of the wind-driven flow to the wind speed, and the deflection angle with respect to the wind direction are estimated by the least square method and the QuikSCAT data. Both the speed factor and the deflection angle change seasonally; the former ranges from approximately 1 to 1.5% and tends to be largest in winter, although the changes would be less significant with respect to the accuracy of the velocity data. Meanwhile, the latter varies from 20 to 80 degree clockwise from the wind direction and becomes largest in summer. This tendency is obvious in the offshore region, but insignificant within the Kuroshio. The results would be discussed with possible seasonal variations of the eddy viscosity due to the vertical stratification and wind drag coefficient..
19. Akira Nagano, Kaoru Ichikawa, Hiroshio Ichikawa, H Tomita, H Tokinaga, Masanori Konda, Stable volume and heat transports of the North Pacific subtropical gyre revealed by identifying the Kuroshio in synoptic hydrography south of Japan, Journal of Geophysical Research, 10.1029/2009JC005747, 115, C09002, 14pp, 115, C09002, doi:10.1029/2009JC005747, 2010.09.
20. Kuroshio Varitations northeast of Taiwan.
21. K. Fukudome, T. Matsuno, C. Liu, K. Ichikawa, Y. Yu, P. Chen, H. Chen, Volume transport flowing into the shelf region of the East China Sea, EOS Trans. AGU, 91, 26, Abstract OS31B-194, West. Pac. Geophys. Meet. Suppl., 2010.06.
22. K. Ichikawa and T. Endoh, Enhanced transport of the subsurface Kuroshio water toward the continental shelf due to mesoscale variations of the Kuroshio northeast of Taiwan, EOS Trans. AGU, 91, 26, Abstract OS24A-06, West. Pac. Geophys. Meet. Suppl., 2010.06.
23. Hiroshi Ichikawa, Akira Nagano, Kaoru Ichikawa, Annual Signal Modulation of the Kuroshio Through-flow Volume Transport South of Japan Leading West Pacific Pattern, Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society (Annex), Venice, Italy, 21-25 September 2009, Hall, J., Harrison, D.E. & Stammer, D., Eds., ESA Publication WPP-306, 2010.04.
24. Kaoru Ichikawa, Synoptic flow structures in the confluence region of the Kuroshio and Ryukyu current, Journal of Geophysical Research, Vol. 114, C06007, doi:10.1029/2008JC005213, 2009.06.
25. Motohiko Kashima, Shin-ichi Ito, Kaoru Ichikawa, Shiro Imawaki, Shin-ichiro Umatani, Hiroshio Uchida and Takashi Setou, Quasiperiodic small meanders of the Kuroshio off Cape Ashizuri and their interannual modulation caused by quasiperiodic arrivals of mesoscale eddies, Journal of Oceanography, 65(1), 73-80, 2009.01.
26. Kaoru Ichikawa, Kuroshio variations in the upstream region as seen by HF radar and satellite altimetry data, International Journal of Remote Sensing, 29(21), 6317-6326, doi:10.1080/01431160802175454, 2008.11.
27. Variations of velocity and transport associated with coastal cyclonic eddies off Shikoku, Japan estimated from moored current meter and IES data,
Koji KAKINOKI, Shiro IMAWAKI, Kaoru ICHIKAWA, Shin-ichiro UMATANI and Motohiko KASHIMA,
RIAM Reports, 135, 53-59.
28. Interannual variability of mesoscale eddy activity at the subtropical fronts region and its influence on the generation of Kuroshio large meander,
Motohiko KASHIMA, Kaoru ICHIKAWA and Makoto SATAKE,
RIAM Reports, 135, 61-67.
29. Tidal Currents North of the Yaeyama Islands as seen by HF radars
Kaoru ICHIKAWA, Ryoko TOKESHI and Shoichiro KOJIMA
RIAM Reports, 135, 77-81.
30. Experimental Estimate of Geostrophic Current from Trajectory Data of Sea-Surface Drifting Buoys
Daisuke AMBE and Kaoru ICHIKAWA,
RIAM Reports, 135, 83-88..
31. Kaoru Ichikawa, Variations of Kuroshio Geostrophic Transport South of Japan Estimated from Long-Term IES Observations, Journal of Oceanography, 64(3), 373-384, 2008.06.
32. A. Nagano, H. Ichikawa, T. Miura, K. Ichikawa, M. Konda, Y. Yoshikawa, K. Obama, and K. Murakami, Reply to comment by Xie-Hua Zhu et al. on "Current system east of the Ryukyu Islands", Journal of Geophysical Research, 113, C03021, doi:10.1029/2007JC004561, 2008.04.
33. Taiwan Warm Current and Kuroshio Branch Current northeast of Taiwan as seen by along- track altimetry data,
Kaoru Ichikawa and Daisuke Ambe.
34. K. Kakinoki, S. Imawaki, K. Ichikawa and S. Umatani, Comparison of Sea Surface Dynamic Heights Estimated from Inverted Echo Sounder Data and Satellite Altimeter Data, 九州大学総合理工学報告(Engineering Sciences Reports, Kyushu University), 29(1), 13-17, 2007.11.
35. Observing Variations of Ocean Bottom Pressure by Satellites, K. Ichikawa, R. Otsuka, K. Ogawa and S. Imawaki, RIAM Report, 133, 173-178, 2007..
36. Kaoru Ichikawa, Current system east of the Ryukyu Islands, Journal of Geophysical Research, Vol. 112, C06009, doi:10.1029/2006JC003917, 2007.06.
37. Tokeshi, R., K. Ichikawa, S. Fujii, K. Sato and S. Kojima, Estimating the geostrophic velocity obtained by HF radar observations in the upstream area of the Kuroshio, Journal of Oceanography, Vol 63(4), 711-720, 2007.06.
38. Kaoru Ichikawa, Flow of abyssal water into Wake Island Passage: Properties and transports from hydrographic surveys, Journal of Geophysical Research, Vol. 112, C04008, doi:10.1029/2006JC004000, 2007.04.
39. K. Ichikawa and R. Tokeshi, Interactions with eddies in the upstream of the Kuroshio as seen by the HF radar and altimetry data, Proceedings of ISRS 2006 PORSEC, ISSN 1226-9743, 969-972, 2006.11.
40. Tokeshi, R., K. Ichikawa, S. Fujii, K. Sato and S. Kojima, Estimating the geostrophic velocity component in the sea surface velocity observed by the HF radar in the upstream of the Kuroshio, Proceedings of ISRS 2006 PORSEC, ISSN 1226-9743, 672-675., 2006.11.
41. Kaoru Ichikawa, Variability of current structure due to the meso-sclae eddies on the bottom slope southeast of Okinawa Island, Journal of Oceanography, 10.1007/s10872-006-0024-z, 61, 6, 1089-1099, 61(6), 1089-1099, 2005.12.
42. Kaoru Ichikawa, Extraordinary subsurface mesoscale eddy detected in the southeast of Okinawa in Feburary 2002, Geophysical Research Letters, 10.1029/2005GL023842, 32, 17, 32, L17602, doi:10.1029/2005GL023842, 2005.09, [URL].
43. Kaoru Ichikawa, Influence of the Kuroshio fluctuations on sea level variations along the south coast of Japan, Journal of Oceanography, 10.1007/s10872-006-0014-1, 61, 5, 979-985, 61, 979-985, 2005.09, [URL].
44. Z. Zhang and K. Ichikawa, Effects of the Kuroshio on coastal sea level south of Japan, 2005 IEEE International Geoscience and Remote Sensing Symposium Proceedings, 5428-5431, 5428-5431
ISBN 0-7803-9051-2, 2005.07.
45. D. Ambe, S. Imawaki, K. Ichikawa and H. Uchida, Detecting the Kuroshio axes south of Japan by using altimeter and drifter data, 2005 IEEE International Geoscience and Remote Sensing Symposium Proceedings, 5424-5427, 5424-5427
ISBN 0-7803-9051-2, 2005.07.
46. K. Ichikawa, Surface velocity monitoring by satellite altimetry and repeated ADCP observations, 2005 IEEE International Geoscience and Remote Sensing Symposium Proceedings, 5420-5423, 5420-5423
ISBN 0-7803-9051-2, 2005.07.
47. K. Ichikawa, N. Gohda, M. Arai and A. Kaneko, Variations of the Subtropical Counter-Current as seen by repeated ADCP and satellite altimetry data, Proceedings of The Indonesia Ocean Forum 2005 and the 13th PAMS/JECSS Workshop, 161-164, 2005.07.
48. Kaoru Ichikawa, Volume transport variability southeast of Okinawa Island estimated from satellite altimeter data, Journal of Oceanography, 10.1007/s10872-005-0004-8, 60, 6, 953-962, 60, 953-962, 2004.11, [URL].
49. Aliasing in repeat observations with inacculate sampling intervals, Kaoru Ichikawa, Oceanography in Japan.
50. Monitoring of the surface currents by repeated ADCP observations and satellite altimeters, K. Ichikawa, N. Gohda, M. Arai and A. Kaneko, Kaiyo Monthly.
51. Estimation of the Kuroshio axis south of Japan by combining satellite altimetry data and drifting buoy trajectories, D. Ambe, S. Imawaki, H. Uchida, and K. Ichikawa.
52. Review: Kuroshio Variation Prediction Experiments, S. Imawaki and K. Ichikawa, Kaiyo Monthly.
53. Kaoru Ichikawa, Estimating the Kuroshio axis south of Japan using combination of satellite altimetry and drifting buoys, Journal of Oceanography, 10.1023/B:JOCE.0000038343.31468.fe, 60, 2, 375-382, Vol. 60, 375-382, 2004.03, [URL].
54. Kaoru Ichikawa, Monitoring surface velocity from repeated ADCP observations and satellite altimetry, Journal of Oceanography, 10.1023/B:JOCE.0000038342.87237.e3, 60, 2, 365-374, Vol. 60, 365-374, 2004.03, [URL].
55. Zhongzhe Zhang and Kaoru Ichikawa, Effect of the Kuroshio on coastal sea level south of Kyushu, Proceedings of 12th PAMS/JECSS Workshop, 4-10-1〜4, 2003.11.
56. Kaoru Ichikawa and Yuichi Sumikawa, Amplitude modulation of a-few-month Kuroshio variations southwest of Kyushu, Proceedings of 12th PAMS/JECSS Workshop, 4-3-1〜4, 2003.11.
57. S. Imawaki, H. Uchida, K. Ichikawa, D. Ambe, Estimating the high-resolution mean sea-surface velocity field by combined use of altimeter and drifter data for geoid model improvement, Space Science Reviews, 10.1023/A:1026106904472, 108, 1-2, 195-204, Vol.108, 195-204, 2003., 2003.11, [URL].
58. Han, I.-S., X.-H. Zhu, J.-H. Park, H. Ichikawa, A. Kaneko, K. Ichikawa and M. Konda, Estimated Northeastward Mean Current Around the East of Okinawa Islands, Proceedings (CD-ROM) of Techno-Ocean 2002, Electric File: /PDF/TL-2-6.pdf, 2002.11.
59. Kaoru Ichikawa and Atsushi Kaneda, Spatial Representability of Coastal Sea Level Variations Near the Kuroshio, Pan Ocean Remote Sensing Conference (PORSEC) 2002 Proceedings, Vol.1, 7-10, 2002.09.
60. Kaoru Ichikawa and Keiko Suito, Capability of the Complex EOF analysis -- with demonstrations to the NCEP data, 九州大学総合理工学報告, 24(1), 23-28, 2002.06.
61. Sea-surface variations as seen by satellite altimetry, K. Ichikawa, Oceanography in Japan.
62. Shiro Imawaki, Shigeru Aoki, Yoichi Fukuda, Kaoru Ichikawa, Shin-ichi Ito, H. Kawamura, M. Kubota, T. Kuragano, K. Matsumoto, T. Nagai, A. Sengoku, H. YOritaka, Mass, heat, and salt transports in the western North Pacific, 8, 62-64, 2001.04.
63. Kaoru Ichikawa, Correlated variations of the Kuroshio in the East China Sea and in the Tokara Strait, Preprint Full Paper for 11th PAMS/JECSS Symposium, 175-178, 2001.04.
64. A. Kaneko, A. Ostrovskii, A. Stuart-Mentecth, K. Takeuchi, T. Yamagata, J.-H. Park, X.-H. Zhu, N. Gohda, H. Ichikawa, K. Ichikawa, A. Isobe, M. Konda, and S. Umatani, Acoustic monitoring of the Kuroshio Current system, Journal of Marine Acoustic Society of Japan, 28(4), 236-255, 2001.01.
65. A. Ostrovskii, A. Kaneko, A. Stuart-Menteth, K. Takeuchi, T. Yamagata, J.-H. Park, X. H. Zhu, N. Gohda, H. Ichikawa, K. Ichikawa, A. Isobe, M. Konda and S. Umatani, Kuroshio Observation Program: Towards Real-Time Monitoring the Japanese Coastal Waters, Ocean and Polar Research, 23(2), 141-160, 2001.01.
66. Kaoru Ichikawa, Variation of the Kuroshio in the Tokara Strait induced by meso-scale eddies, Journal of Oceanography, 57(1), 55-68, 2001.01, [URL].
67. Velocity variations in the western North Pacific, N. Gohda, K. Ichikawa, M. Arai, H. Zheng and Y. Zhu, Kaiyo Monthly.
68. 1-month prediction of the Kuroshio path variation, T. Awaji, N. Komori, T. Kuragano, Y. Ishikawa, K. Akitomo, K. Ichikawa and H. Nakamura, Kaiyo Monthly.
69. K. Ichikawa and A. Kaneda, Coastal impacts of offshore meso-scale eddies through the Kuroshio variation, La Mer, 38(4), 219-226, 2000.01.
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