Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Yukari Hara Last modified date:2023.11.22

Assistant Professor / Division of Earth Environment Dynamics / Research Institute for Applied Mechanics

1. Xiaole Pan, Itsushi Uno, Zhe Wang, Shigekazu Yamamoto, Yukari Hara, Zifa Wang, Seasonal variabilities in chemical compounds and acidity of aerosol particles at urban site in the west Pacific, Environmental Pollution, 10.1016/j.envpol.2017.11.089, 237, 868-877, 2018.06, Mass concentrations of chemical compounds in both PM2.5 (particle aerodynamic diameter, Dp 2.5-10 (2.5 2.5 and sulfate had distinct seasonal variabilities with maxima in spring and winter, mostly due to long-range transport with the prevailing westerly wind. Mass concentration of nitrate in PM2.5 (fNO3) showed an obvious warm-season-low and cold-season-high pattern as a result of both gas-aerosol phase equilibrium processes under high temperature conditions as well as transport. Nitrate in PM2.5-10 (cNO3) increased during long-range transport of dust, implying the great importance of heterogeneous processes at the surface of coarse mode particles. In this study, Δ[H+] (derived from the difference in pH of extract liquid with/without sampling) was used to indicate the acidity of particles. We found that acidity of particles in PM2.5 (fΔH) was mostly positive with a maximum in August because of the large fraction of nitrate and sulfate. Acidity of particles in PM2.5-10 (cΔH) was negative in winter and spring due to presence of alkaline matter from crustal sources. This study highlights the great importance of anthropogenic pollutants on the acidity of particles in the western Pacific Ocean and further impact on the marine environment and climate. Meteorology and transport played a key role in the allocation of aerosol phase nitrate in PM2.5, PM2.5-10. Seasonal variability of acidity of PM2.5 was mainly attributed to fraction of water-soluble secondary inorganics and source regions..
2. Yukari Hara ,Tomoaki Nishizawa , Nobuo Sugimoto , Kazuo Osada , Keiya Yumimoto , Itsushi Uno , Rei Kudo , Hiroshi Ishimoto, Retrieval of aerosol components using Multi-Wavelength Mie-Raman Lidar and comparison with ground aerosol sampling, Remote Sensing,, 2018.06.
3. Itsushi Uno, Kazuo Osada, Keiya Yumimoto, Zhe Wang, Syuichi Itahashi, Xiaole Pan, Yukari Hara, Shigekazu Yamamoto, Tomoaki Nishizawa, Importance of long-range nitrate transport based on long-term observation and modeling of dust and pollutants over East Asia, Aerosol and Air Quality Research, 10.4209/aaqr.2016.11.0494, 17, 12, 3052-3064, 2017.12, Long-term synergetic fine and coarse mode aerosol observations were analyzed at 1-h intervals at Fukuoka, Japan, from January to June 2015. The GEOS-Chem chemical transport model, including dust and sea-salt acid uptake processes, was used for detailed analysis of observation data. Several Asian dust events and long-range anthropogenic aerosol transport events were observed during our analysis period, and the numerical model generally explained the observed time variation for both fine and coarse mode aerosols. We found that (i) the majority of fine mode NO3 can be considered as long-range transport (LRT) outside of Japan during the cold season, and (ii) the peak timing of fine mode NO3 coincided with that of SO4 , indicating that both aerosols are controlled by LRT. Also, an observed mass concentration ratio of NO3 /SO4 2– > 0.9 occurred during the cold season, indicating the importance of NO3 as a major contributor to the PM2.5 mass fraction. Finally, we clearly showed that large-scale dust-nitrate outflow from China to Fukuoka was confirmed in all cases of dust events, indicating that the anthropogenic NOx is converted to dust-nitrate and transported to Japan with dust. These results demonstrate the importance of anthropogenic NO3 LRT during the cold season and dust-nitrate LRT for all dust events (even in June)..
4. Itsushi Uno, Kazuo Osada, Keiya Yumimoto, Zhe Wang, Syuichi Itahashi, Xiaole Pan, Yukari Hara, Yugo Kanaya, Shigekazu Yamamoto, Thomas Duncan Fairlie, Seasonal variation of fine- and coarse-mode nitrates and related aerosols over East Asia
Synergetic observations and chemical transport model analysis, Atmospheric Chemistry and Physics, 10.5194/acp-17-14181-2017, 17, 23, 14181-14197, 2017.11, We analyzed long-term fine- and coarse-mode synergetic observations of nitrate and related aerosols (SO2 4 , NO3 , NHC4 , NaC, Ca2C) at Fukuoka (33.52 N, 130.47 E) from August 2014 to October 2015. A Goddard Earth Observing System chemical transport model (GEOS-Chem) including dust and sea salt acid uptake processes was used to assess the observed seasonal variation and the impact of long-range transport (LRT) from the Asian continent. For fine aerosols (fSO2 4 , fNO3 , and fNHC4 ), numerical results explained the seasonal changes, and a sensitivity analysis excluding Japanese domestic emissions clarified the LRT fraction at Fukuoka (85% for fSO2 4 , 47% for fNO3 , 73% for fNHC4 ). Observational data confirmed that coarse NO3 (cNO3 ) made up the largest proportion (i.e., 40-55 %) of the total nitrate (defined as the sum of fNO3 , cNO3 , and HNO3) during the winter, while HNO3 gas constituted approximately 40% of the total nitrate in summer and fNO3 peaked during the winter. Large-scale dust-nitrate (mainly cNO3 ) outflow from China to Fukuoka was confirmed during all dust events that occurred between January and June. The modeled cNO3 was in good agreement with observations between July and November (mainly coming from sea salt NO3 ). During the winter, however, the model underestimated cNO3 levels compared to the observed levels. The reason for this underestimation was examined statistically using multiple regression analysis (MRA).We used cNaC, nsscCa2 C, and cNHC4 as independent variables to describe the observed cNO3 levels; these variables were considered representative of sea salt cNO3 , dust cNO3 , and cNO3 accompanied by cNHC4 ), respectively. The MRA results explained the observed seasonal changes in dust cNO3 and indicated that the dust-acid uptake scheme reproduced the observed dust-nitrate levels even in winter. The annual average contributions of each component were 43% (sea salt cNO3 ), 19% (dust cNO3 ), and 38% (cNHC4 term). The MRA dust-cNO3 component had a high value during the dust season, and the sea salt component made a large contribution throughout the year. During the winter, cNHC4 term made a large contribution. The model did not include aerosol microphysical processes (such as condensation and coagulation between the fine anthropogenic aerosols NO3 and SO2 4 and coarse particles), and our results suggest that inclusion of aerosol microphysical processes is critical when studying observed cNO3 formation, especially in winter..
5. Tomoaki Nishizawa, Nobuo Sugimoto, Ichiro Matsui, Atsushi Shimizu, Yukari Hara, Itsushi Uno, Kazuaki Yasunaga, Rei Kudo, Sang Woo Kim, Ground-based network observation using Mie–Raman lidars and multi-wavelength Raman lidars and algorithm to retrieve distributions of aerosol components, Journal of Quantitative Spectroscopy and Radiative Transfer, 10.1016/j.jqsrt.2016.06.031, 188, 79-93, 2017.02, We improved two-wavelength polarization Mie-scattering lidars at several main sites of the Asian dust and aerosol lidar observation network (AD-Net) by adding a nitrogen Raman scatter measurement channel at 607 nm and have conducted ground-based network observation with the improved Mie–Raman lidars (MRL) in East Asia since 2009. This MRL provides 1α+2β+1δ data at nighttime: extinction coefficient (α532), backscatter coefficient (β532), and depolarization ratio (δ532) of particles at 532 nm and an attenuated backscatter coefficient at 1064 nm (βat,1064). Furthermore, we developed a Multi-wavelength Mie-Raman lidar (MMRL) providing 2α+3β+2δ data (α at 355 and 532 nm; β at 355 and 532; βat at 1064 nm; and δ at 355 and 532 nm) and constructed MMRLs at several main sites of the AD-Net. We identified an aerosol-rich layer and height of the planetary boundary layer (PBL) using βat,1064 data, and derived aerosol optical properties (AOPs, for example, αa, βa, δa, and lidar ratio (Sa)). We demonstrated that AOPs cloud be derived with appropriate accuracy. Seasonal means of AOPs in the PBL were evaluated for each MRL observation site using three-year data from 2010 through 2012; the AOPs changed according to each season and region. For example, Sa,532 at Fukue, Japan, were 44±15 sr in winter and 49±17 in summer; those at Seoul, Korea, were 56±18 sr in winter and 62±15 sr in summer. We developed an algorithm to estimate extinction coefficients at 532 nm for black carbon, dust, sea-salt, and air-pollution aerosols consisting of a mixture of sulfate, nitrate, and organic-carbon substances using the 1α532+2β532 and 1064+1δ532 data. With this method, we assume an external mixture of aerosol components and prescribe their size distributions, refractive indexes, and particle shapes. We applied the algorithm to the observed data to demonstrate the performance of the algorithm and determined the vertical structure for each aerosol component..
6. Yukari Hara, Tomoaki Nishizawa, Nobuo Sugimoto, Ichiro Matsui, Xiaole Pan, Hiroshi Kobayashi, Kazuo Osada, Itsushi Uno, Optical properties of mixed aerosol layers over Japan derived with multi-wavelength Mie–Raman lidar system, Journal of Quantitative Spectroscopy and Radiative Transfer, 10.1016/j.jqsrt.2016.06.038, 188, 20-27, 2017.02, Mixing state of aerosols and optical properties including lidar ratio, particle depolarization ratio, and Ångström exponent were investigated at Fukuoka in western Japan using a multi-wavelength Mie–Raman lidar (MMRL), various aerosol mass-concentration measurements, and a polarization optical particle counter during Winter–Spring 2015. Aerosol extinction coefficient, backscatter coefficient, and depolarization at 355 and 532 nm and attenuated backscatter coefficient at 1064 nm are obtained from the MMRL measurements. Ten aerosol episodes were classified into three categories (air pollution, mineral dust, and marine aerosol) based on aerosol mass-concentration measurements in the fine-mode (particle diameter Dppf). The mean particle depolarization ratios of 13±8% at 355 nm and 16±6% at 532 nm also suggest mixing of mineral dust and anthropogenic fine-mode aerosols. The lowest lidar ratio was obtained for marine case. Classification of aerosol types using the lidar ratio and particle depolarization ratio was conducted based on the results obtained in this study. The classified aerosol types almost corresponded to aerosol category obtained by previous studies. We found no remarkable correlation between the fraction of black carbon and the lidar ratio: this might be due to the complexity of the mixing state among various aerosols. The obtained lidar ratio was rather correlated with the ratio of PMf to PM10, representing the mixing state of fine- and coarse-mode particles..
7. Xiaole Pan, Itsushi Uno, Yukari Hara, Kazuo Osada, Shigekazu Yamamoto, Zhe Wang, Nobuo Sugimoto, Hiroshi Kobayashi, Zifa Wang, Polarization properties of aerosol particles over western Japan
Classification, seasonal variation, and implications for air quality, Atmospheric Chemistry and Physics, 10.5194/acp-16-9863-2016, 16, 15, 9863-9873, 2016.08, Ground-based observation of the polarization properties of aerosol particles using a polarization optical particle counter (POPC) was made from 27 October 2013, to 31 December 2015, at a suburban site in the Kyushu area of Japan. We found that the depolarization ratio (DR, the fraction of s-polarized signal in the total backward light scattering signal) of aerosol particles showed prominent seasonal variability, with peaks in spring (0.21-0.23) and winter (0.19-0.23), and a minimum value (0.09-0.14) in summer. The aerosol compositions in both fine mode (aerodynamic diameter of particle, Dp p 1 μm) particles. Occurrence of substandard air quality days in Kyushu was closely related with mixed type (coexistence of anthropogenic pollutants and dust particles in the atmosphere), especially in winter and spring, indicating that dust events in the Asian continent played a key role in the cross-boundary transport of continental pollution. Backward trajectory analysis demonstrated that air masses originating from the western Pacific contained large amounts of spherical particles due to the influence of sea salt, especially in summer; however, for air masses from the Asian continent, the dependence of number fraction of spherical particles on air relative humidity was insignificant, indicating the predominance of less-hygroscopic substances (e.g., mineral dust), although the mass concentrations of anthropogenic pollutants were elevated..
8. Kana Nagashima, Yoshiaki Suzuki, Tomohisa Irino, Takeshi Nakagawa, Ryuji Tada, 原 由香里, Kazuyoshi Yamada, Yasunori Kurosaki, Asian dust transport during the last century recorded in Lake Suigetsu sediments, Geophysical Research Letters, doi:10.1002/ 2015GL067589, 2016.03.
9. Kana Nagashima, Yoshiaki Suzuki, Tomohisa Irino, Takeshi Nakagawa, Ryuji Tada, Yukari Hara, Kazuyoshi Yamada, Yasunori Kurosaki, Asian dust transport during the last century recorded in Lake Suigetsu sediments, Geophysical Research Letters, 10.1002/2015GL067589, 43, 6, 2835-2842, 2016.03, Asian dust has a significant impact on the natural environment. Its variability on multiple timescales modulates the ocean biogeochemistry and climate. We demonstrate that temporal changes in the deposition flux of Aeolian dust recorded in sediments from Lake Suigetsu, central Japan, during the last century exhibit a continuous decreasing trend and a decadal-scale decrease in 1952-1974. The former decreasing trend can be explained by a decrease in the dust storm frequency at source regions due to the warming of Mongolia in the twentieth century, suggesting future decrease of Asian dust transport with further warming in Mongolia. Decadal-scale decrease of Aeolian dust is explained by weaker westerlies in lower latitudes in central Japan, reflecting a weaker Aleutian Low during the corresponding period. Decadal-scale westerly change probably causes north-south shifts of the dominant dust transport path, which affects subarctic northern Pacific Ocean biogeochemistry by changing the micronutrient iron supply..
10. PAN XIAOLE, 鵜野 伊津志, 原 由香里, 長田 和雄, 山本 重一, Z. Wang, 杉本 伸夫, 小林 拓, Z. F. Wang, Polarization properties of aerosol particles over western Japan: classification, seasonal variation, and implications for air quality, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2015-904, 2016.01.
11. PAN XIAOLE, 鵜野 伊津志, 原 由香里, 栗林 正俊, 小林 拓, 杉本伸夫, 山本重一, 下原 孝章, Observation of the simultaneous transport of Asian mineral dust aerosols with anthropogenic pollutants using a POPC during a long-lasting dust event in late spring 2014, GEOPHYSICAL RESEARCH LETTERS, 10.1002/2014GL062491, 2015.03.
12. Xiaole Pan, Itsushi Uno, Yukari Hara, Masatoshi Kuribayashi, Hiroshi Kobayashi, Nobuo Sugimoto, Shigekazu Yamamoto, Takaaki Shimohara, Zifa Wang, Observation of the simultaneous transport of Asian mineral dust aerosols with anthropogenic pollutants using a POPC during a long-lasting dust event in late spring 2014, Geophysical Research Letters, 10.1002/2014GL062491, 42, 5, 1593-1598, 2015.03, We observed a long-lasting dust event from 25 May to 2 June 2014, using a polarization optical particle counter (POPC). The transport of dust plumes over East Asia was verified on the basis of observations of Moderate Resolution Imaging Spectroradiometer, a lidar network, and surface synoptic observation stations. Mixing of dust and anthropogenic pollutants was investigated according to the variation in the depolarization ratio as a function of particle size. The nonsphericity of dust particles varied due to the impact of anthropogenic pollutants on their pathway. In the coarse mode, dust particles always had a clear nonspherical configuration, although large amounts of nitrate were also present. Supermicron particles are occasionally present in a spherical configuration, possibly due to the complex mixing of natural dust and anthropogenic particles. Statistically, ~64% of the total nitrate mass was deemed to be transported from outside of Japan due to a trapping effect in the dust plume..
13. 鵜野 伊津志, 杉本伸夫, 清水厚, 弓本桂也, 原 由香里, Zifa Wang, Record heavy PM2.5 air pollution over China in January 2013: Vertical and Horizontal Dimensions, Scientific Online Letters on the Atmosphere,, 10, 136-140, 2014.09.
14. Itsushi Uno, Nobuo Sugimoto, Atsushi Shimizu, Keiya Yumimoto, Yukari Hara, Zifa Wang, Record heavy PM2.5 air pollution over China in January 2013
Vertical and horizontal dimensions, Scientific Online Letters on the Atmosphere, 10.2151/sola.2014-028, 10, 1, 136-140, 2014.01, Record heavy PM2.5 air pollution (maximum concentration of ∼1 mg m-3) observed over China in January 2013 was analyzed. The vertical and horizontal scales of the pollution layer are critically important parameters for the analysis of pollution phenomena, but they are difficult to measure. This is because the PM2.5 aerosol concentration is so high that ordinary remote-sensing methods such as ground-based and space-borne lidar inversion are difficult to apply. First, we showed the detailed time-height structure of aerosol extinction coefficients based on Beijing lidar observation, by assuming a non-zero boundary extinction coefficient and using 3D chemical transport modeling (CTM). The aerosol structure derived from lidar observations and the CTM results were in close agreement. Using ground-based lidar, we also found that a shallow aerosol layer (height of 200-300 m) remained over Beijing for a long time. We also successfully showed that the horizontal extent of the aerosol layer over the China Plain was several hundred km based on CALIOP observations and CTM..
15. Nobuo Sugimoto, Hara Yukari, Atsushi Shimizu, Tomoaki Nishizawa, Ichiro Matsui, Masataka Nishikawa, Analysis of Dust Events in 2008 and 2009 Using the Lidar Network, Surface
Observations and the CFORS Model, Asia-Pacific J. Atmos. Sci., 49, 2013.01.
16. Nobuo Sugimoto, Yukari Hara, Atsushi Shimizu, Tomoaki Nishizawa, Ichiro Matsui, Masataka Nishikawa, Analysis of dust events in 2008 and 2009 using the lidar network, surface observations and the CFORS model, Asia-Pacific Journal of Atmospheric Sciences, 10.1007/s13143-013-0004-3, 49, 1, 27-39, 2013.01, The Asian dust events in 2008 (May 24-June 4 in 2008) and in 2009 (March 12-25, October 13-26, and December 15-28 in 2009) were analyzed with the lidar network observations, surface observations in China, Korea, Japan, and Mongolia, and with the chemical transport model CFORS. Transport of Asian dust and mixing of dust with air pollution aerosols were studied. The event of May 24 to June 4 in 2008 was a significant event unusually late in the spring dust season. The dust event of March 12-25, 2009 was an interesting example of elevated dust layer, and transport of dust from the elevated dust layer to the ground by the boundary layer activity was observed with the lidars and surface observations in Japan. The concentration of air pollution aerosols was relatively high during the dust event, and the results suggest that vertical structure as well as transport path is important for the mixing of dust and air pollution aerosols. The dust events in October and December 2009 were examples of dust events in autumn and winter. The online mode CFORS reproduced the observation data generally well, except for the event of May 24 to June 4 in 2008. The results of the fourdimensional variational assimilation of the lidar network data reproduced the dust concentration in Korea and Japan reasonably in that event..
17. Yumimoto, K.,I. Uno,N. Sugimoto,A. Shimizu, Y. Hara and T. Takemura, Size-resolved adjoint inversion of Asian dust, Geophysical Research Letters, doi:10.1029/2012GL053890, 39, 2012.12.
18. Keiya Yumimoto, Itsushi Uno, N. Sugimoto, A. Shimizu, Yukari Hara, Toshihiko Takemura, Size-resolved adjoint inversion of Asian dust, Geophysical Research Letters, 10.1029/2012GL053890, 39, 24, 2012.12, We expanded the variational assimilation system of a regional dust model by using size-resolved inversion. Dust emissions and particle-size distributions of a severe dust and sandstorm (DSS) in April 2005 were inversely optimized with optical measurements by the National Institute for Environmental Studies lidar network. The inversion results successfully compensated underestimates by the original model and increased the ngstrm exponent around the DSS core by 13-17%, shifting the particle-size distribution to finer. The a posteriori size distribution was distinctly different between eastern and western source regions. In the western regions, dust emissions in the 3.19 and 5.06 m size bins increased considerably, and the peak size shifted from 5.06 to 3.19 m, whereas in the eastern regions, emissions of finer particles (bins 0.82-2.01 m) increased. Differences in vegetation and soil type and moisture between eastern and western regions might explain the characteristics of the inverted size distribution..
19. Hara, Y., I. Uno, A. Shimizu, N. Sugimoto, I. Matsui, K. Yumimoto, J. Kurokawa, T. Ohara, and Z. Liu, Seasonal characteristics of spherical aerosol distribution in eastern Asia: Integrated analysis using ground/space-based lidars and a chemical transport model, Scientific online letters on the atmosphere, 7, 121-124, 2011.08.
20. Itsushi Uno, K. Eguchi, Keiya Yumimoto, Z. Liu, Yukari Hara, N. Sugimoto, A. Shimizu, Toshihiko Takemura, Large Asian dust layers continuously reached North America in April 2010, Atmospheric Chemistry and Physics, 10.5194/acp-11-7333-2011, 11, 14, 7333-7341, 2011.08, The NASA space-borne Mie-lidar system CALIPSO/CALIOP revealed that multiple large Asian dust layers with a horizontal scale of 2000-3000 km reached North America, occupying the full troposphere, in April 2010. This kind of dust layer transport has not been reported before. Our analysis of CALIOP data and global aerosol model results revealed that frequent dust emissions occurred in northwestern China because of stronger-than-average near-surface winds, and that strong stable westerly winds carried the Asian dust from northwestern China to the central Pacific Ocean. A negative pressure anomaly was located in the eastern Pacific Ocean, and the main dust transport path was split into two branches: a northern path and a southern path over North America. Northern-path dust was trapped and stagnant for a longer time than southern path dust and finally subsided under a high-pressure system. Dust along the southern path reached the central US. These complex conditions resulted in a multi-layered structure of dust over North America..
21. Uno, I., K. Eguchi, K. Yumimoto, Z. Liu, Y. Hara, N. Sugimoto, A. Shimizu, and T. Takemura, Large Asia dust layers continuously reached North America in April 2010, Atmospheric Chemistry and Physics, 11, 7333-7341, 2011.02.
22. Sugimoto, N., Y. Hara, A. Shimizu, K. Yumimoto, I. Uno, and M. Nishikawa, Comparison of Surface Observation and a Regional Dust Transport Model Assimilated with Lidar Network Data in Asian Dust Event of March 29 to April 2, Scientific online letters on the atmosphere, 7A, 13-16, 2011.01.
23. Nobuo Sugimoto, Yukari Hara, Atsushi Shimizu, Keiya Yumimoto, Itsushi Uno, Masataka Nishikawa, Comparison of surface observations and a regional dust transport model assimilated with lidar network data in Asian dust event of March 29 to April 2, 2007, Scientific Online Letters on the Atmosphere, 10.2151/sola.7A-004, 7, A, 13-16, 2011.01, Surface observation data taken in Mongolia, China, Korea and Japan during the Asian dust event of March 29 to April 2, 2007 were compared with a regional dust transport model assimilated with the lidar network data. The assimilated model reproduced the reported dust event in Mongolia and the observed PM10 concentrations in Korea and Japan very well. The mass/extinction conversion factor (MEF) obtained from the lidar dust extinction coefficient and PM10 concentration was also compared with the assimilated model for Seoul and Tsukuba where both the lidar and PM10 data were available. The MEFs for PM10 and PM2.5 (the ratio of dust-only PM10 or PM2.5 to the dust extinction coefficient) were calculated with the assimilated model. The modeled MEF for PM10 reproduced the observed MEF reasonably and exhibited spatial and temporal variations reflecting the variations in the dust particle size distribution. The modeled MEF for PM2.5 had much less variation. This indicates that the dust extinction coefficient has a higher correlation with dust PM2.5 and should be a useful index for studying the effect of dust on human health..
24. Yukari Hara, Itsushi Uno, Atsushi Shimizu, Nobuo Sugimoto, Ichiro Matsui, Keiya Yumimoto, Jun Ichi Kurokawa, Toshimasa Ohara, Zhaoyan Liu, Seasonal characteristics of spherical aerosol distribution in eastern Asia
Integrated analysis using ground/space-based lidars and a chemical transport model, Scientific Online Letters on the Atmosphere, 10.2151/sola.2011-031, 7, 1, 121-124, 2011.01, Seasonal characteristics of spherical aerosol distributions in eastern Asia were investigated between July 2006 and December 2008 using data from ground-based and space-borne lidar observations and the Community Multi-scale Air Quality Modeling System (CMAQ) chemical transport model simulation. The seasonal variation of spherical aerosol optical thickness (AOT) observed at four ground lidar stations surrounding the East China Sea (Beijing, Guangzhou, Seoul, and Hedo/Okinawa) was generally consistent with CMAQ simulation results. Detailed analyses confirmed clear regional differences in aerosol compositions. Analyses of aerosol vertical profiles revealed that the spherical aerosol variation is greatest in Beijing, with scale height varying between 720 m and 2100 m. The analyses also revealed that the seasonal variation patterns of spherical AOT are classifiable into 'summer peak' and 'summer trough' types. Northern sites (Beijing and Seoul) are of the summer peak type; southern sites (Guangzhou and Okinawa) show the summer trough pattern. Our analyses demonstrated that the Asian summer-winter monsoon system plays a major role in regulating such seasonal variation. The CMAQ simulated variation of spherical aerosols is well correlated to the synoptic scale monsoon variation..
25. Nobuo Sugimoto, Ichiro Matsui, Atsushi Shimizu, Tomoaki Nishizawa, Yukari Hara, Itsushi Uno, Lidar network observation of tropospheric aerosols, Lidar Remote Sensing for Environmental Monitoring XI Lidar Remote Sensing for Environmental Monitoring XI, 10.1117/12.869900, 7860, 2010.12, This paper presents the results of recent studies on tropospheric aerosols, including Asian dust and forest fire smoke using the NIES Lidar Network, CALIPSO/CALIOP and chemical transport models. The NIES Lidar Network is a network of two-wavelength (532nm, 1064nm) polarization (532nm) lidars in East Asia. Currently the lidars are continuously operated at about 20 locations in Japan, Korea, China, Mongolia, and Thailand, in cooperation with various research institutes and universities. The network is a part of the Asian Dust Network (ADNet), SKYNET, and the GAW Aerosol Lidar Observation Network (GALION). The data from most of the lidar stations are transferred to NIES in realtime and automatically processed to derive the attenuated backscattering coefficients at 532nm and 1064nm, the volume depolarization ratio at 532nm, and the estimated dust and spherical aerosol extinction coefficients at 532nm. The data from the network are used in various research activities on Asian dust, regional air pollution, and the effects of aerosols on climate and the environment. The data are also used for real-time monitoring (for early warning assessment) of Asian dust. The results of recent studies on long-range transport of Asian dust, optical characteristics of forest fire plumes, aerosol climatology, etc. will be described..
26. Syuichi Itahashi, Keiya Yumimoto, Itsushi Uno, Kenta Eguchi, Toshihiko Takemura, Yukari Hara, Atsushi Shimizu, Nobuo Sugimoto, Zhaoyan Liu, Structure of dust and air pollutant outflow over East Asia in the spring, Geophysical Research Letters, 10.1029/2010GL044776, 37, 20, 2010.10, Springtime outflow of Asian dust and air pollutants was investigated by a synergetic analysis of ground-based/space-borne Lidar observations and numerical models. We identified two prominent outflow patterns, and its occurrence frequency. Pattern I was induced within a typical warm-sector which lifted up dust particles into the free troposphere, and the existence of two sequential low-pressure systems played an important role. Pattern II was a behind cold front outbreak. Atmospheric stratification was significantly different; Pattern I had weak stratification within the troposphere (potential temperature gradient of ∼2-3.4 K/km), and most of elevated dust layer (typically horizontally 1500-2000 km, vertically 2.5-4 km AGL) remained unmixed with pollutants. Pattern II was characterized by a strong stratification of ∼5 K/km; dust and pollutants were trapped and well mixed within the PBL, forming polluted dust. Among the six cases of large-scale dust/pollutants outbreaks, only two cases are belonged to Pattern I..
27. Sugimoto, N., Y. Hara, K. Yumimoto, I. Uno, M. Nishikawa, and J. Dulam, Dust Emission Estimated with an Assimilated Dust Transport Model Using Lidar Network Data and Vegetation Growth in the Gobi Desert in Mongolia, Scientific online letters on the atmosphere, 6, 125-128, 2010.07.
28. Nobuo Sugimoto, Yukari Hara, Keiya Yumimoto, Itsushi Uno, Masataka Nishikawa, Jugder Dulam, Dust emission estimated with an assimilated dust transport model using lidar network data and vegetation growth in the gobi desert in Mongolia, Scientific Online Letters on the Atmosphere, 10.2151/sola.2010-032, 6, 1, 125-128, 2010, Dust emission estimated with a 4D-Var data assimilation system using ground-based lidar network data was compared with vegetation growth data based on visual observations in the Gobi desert in Mongolia in the spring of 2007. The dust emission flux estimated with the data assimilation system was less than that estimated without data assimilation in the dust event of May 21-30 and was the opposite in the event of March 25-April 3. The threshold surface friction velocity estimated from the results of the data assimilation was less than 0.3 m s-1 in the dust event of March 25-April 3 and was ~0.36 m s-1 in the event of May 21-30. The difference between the two events was qualitatively explained by the vegetation growth data. The accumulated precipitation during the period was ~2 mm. The results show that vegetation growth with slight precipitation in the Gobi desert may significantly reduce dust emission..
29. Itsushi Uno, Kenta Eguchi, Keiya Yumimoto, Toshihiko Takemura, Atsushi Shimizu, Mitsuo Uematsu, Zhaoyan Liu, Zifa Wang, Yukari Hara, Nobuo Sugimoto, Asian dust transported one full circuit around theglobe, Nature Geoscience, 10.1038/ngeo583, 2, 8, 557-560, 2009.08, Mineral dust is usually transported long distances in the lower troposphere. There are examples of Asian dust being transported across the Pacific Ocean, and traces of Asian dust have also been found in ice and snow cores in Greenland and the French Alps. Here, we use measurements from the Cloud-Aerosol Lidar with Orthogonal Polarization, an air parcel trajectory model and a three-dimensional aerosol transport model to map the transport of dust clouds generated during a storm in Chinas Taklimakan Desert during May 2007. We show that the dust-veiled clouds were lofted to the upper troposphere around 8-10 km above the Earths surface and transported more than one full circuit around the globe in about 13 days. When the dust reached the northwestern Pacific Ocean for the second time, the subsidence of a large-scale high-pressure system caused it to descend into the lower troposphere; some of the dust was then deposited over the ocean. Our analysis also indicates that the dust particles may have acted as ice nuclei in these high-altitude clouds, leading to the formation of cirrus clouds. We suggest that Asian dust can influence the global radiation budget by stimulating cirrus cloud formation and marine ecosystems by supplying nutrients to the open ocean..
30. Uno, I., K. Eguchi, K. Yumimoto, T. Takemura, A. Shimizu, M. Uematsu, Z. Liu, Z. Wang, Y. Hara, N. Sugimoto, Asian dust transported one full circuit around the globe, Nature geoscience, doi:10.1038/NGEO583, 2009.07.
31. Hara, Y., K. Yumimoto, I. Uno, A. Shimizu, N. Sugimoto, Z. Liu, D. M. Winker, Asian dust outflow in the PBL and free atmosphere retrieved by NASA CALIPSO and an assimilated dust transport model, Atmospheric Chemistry and Physics, 9, 1227-1239, 2009.02.
32. Yukari Hara, Keiya Yumimoto, Itsushi Uno, A. Shimizu, N. Sugimoto, Z. Liu, D. M.Winker, Asian dust outflow in the PBL and free atmosphere retrieved by NASA CALIPSO and an assimilated dust transport model, Atmospheric Chemistry and Physics, 10.5194/acp-9-1227-2009, 9, 4, 1227-1239, 2009.02, Three-dimensional structures of Asian dust transport in the planetary boundary layer (PBL) and free atmosphere occurring successively during the end of May 2007 were clarified using results of space-borne backscatter lidar, Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and results obtained using a data-assimilated version of a dust transport model (RC4) based on a groundbased NIES lidar network. The dust layer depths and the vertical and horizontal structure simulated by RC4 agreed with those of CALIOP observations from the dust source region to the far-downstream region. Two important transport mechanisms of Asian dust in the PBL and free atmosphere were clarified: a low-level dust outbreak within the dry slot region of a well-developed low-pressure system, and formation of an elevated dust layer within the warm sector of a low-pressure system. We also represent the aging of pure dust particles using the particle depolarization ratio (PDR) at 532 nm and the color ratio (CR) at 1064 nm and 532 nm. Aerosols with high PDR were observed uniformly over the dust source region. While the dust cloud was transported to the eastern downwind regions, aerosols with low PDR and high CR occur in the layer of less than 1 km height, suggesting a mixing state of spherical aerosols and dust in the surface layer..
33. Hara, Y., I. Uno, K. Yumimoto, M. Tanaka, A. Shimizu, N. Sugimoto, Z. Liu, Summertime Taklimakan Dust Structure, Geophysical Research Letters, doi:10.1029/2008GL035630, 35, L23801, 2008.12.
34. Nobuo Sugimoto, Ichiro Matsui, Atsushi Shimizu, Tomoaki Nishizawa, 原 由香里, Chenbo Xie, 鵜野 伊津志, Keiya Yumimoto, Zifa Wang, Soon-Chang Yoon, Lidar network observations of Tropospheric Aerosols, Proc. SPIE 7153, Lidar Remote Sensing for Environmental Monitoring IX, doi:10.1117/12.806540, 2008.12.
35. Nobuo Sugimoto, Ichiro Matsui, Atsushi Shimizu, Tomoaki Nishizawa, Yukari Hara, Chenbo Xie, Itsushi Uno, Keiya Yumimoto, Zifa Wang, Soon Chang Yoon, Lidar network observations of tropospheric aerosols, Lidar Remote Sensing for Environmental Monitoring IX Lidar Remote Sensing for Environmental Monitoring IX, 10.1117/12.806540, 7153, 2008.12, Observations of tropospheric aerosols (mineral dust, air-pollution aerosols, etc.) and clouds are being conducted using a network of two-wavelength (1064nm, 532nm) polarization (532nm) lidars in the East Asian region. Currently, the lidars are operated continuously at 23 locations in Japan, Korea, China, Mongolia and Thailand. A real-time data processing system was developed for the network, and the data products such as the attenuated backscatter coefficients and the estimated extinction coefficients for non-spherical and spherical aerosols are generated automatically for online network stations. The data are used in the real-time monitoring of Asian dust as well as in the studies of regional air pollution and climate change..
36. Hara, Y., A. Shimizu, N. Sugimoto, K. Yumimoto, I. Uno, 3D transport structure of Asian dust retrieved by NASA CALIOP and a dust transport model assimilated with the NIES LIDAR network, Reviewed and revised paper presented at the 24th International Laser Radar Conference, 762-765, 2008.06.
37. I.Uno, K. Yumimoto, A. Shimizu, Y. Hara, N. Sugimoto, Z. Wang, Z. Liu, D. M. Winker, 3D structure of Asian dust transport revealed by CALIPSO lidar and a 4DVAR dust model, Geophysical Research Letters, doi:10.1029/2007GL032329, 35, L06803, 2008.03.
38. I.Uno, M. Uematsu, Y. Hara, Y. J. He, T. Ohara, A. Mori, T. Kamaya, K. Murano, Y. Sadanaga, H. Bandow, Numerical study of the atmospheric input of anthropogenic total nitrate to the marginal seas in the western North Pacific region, Geophysical Research Letters, doi:10.1029/2007GL030338, 34, L17817, 2007.06.
39. I. Uno, Z. Wang, M. Chiba, Y.S. Chun, S.L. Gong, Y. Hara, E. Jung, S.S. Lee, M. Liu, M. Mikami, S. Music, S. Nickovic, S. Satake, Y. Shao, Z. Song, N. Sugimoto, T. Tanaka, and D. Westphal , DUST MODEL INTERCOMPARISON (DMIP) STUDY OVER ASIA – Overview, Journal of Geophysical Research, doi:10.1029/2005JD006575, 111, D12213, 2006.06.
40. Hara, Y., I. Uno and Z. Wang, Long-term Variation of Asian Dust and Related Climate Factors, Atmospheric Environment, 40, 6730-6740, 2006.05.
41. M. Mikami, G.Y. Shi, I. Uno, S. Yabuki, Y. Iwasaka, M. Yasui, T. Aoki, T.Y. Tanaka, Y. Kurosaki, K. Masuda, A. Uchiyama, A. Matsuki, T. Sakai, T. Takemi, M. Nakawo, N. Seino, M. Ishizuka, S. Satake, K. Fujita, Y. Hara, K. Kai, S. Kanayama, M. Hayashi, M. Du, Y. Kanai, Y. Yamada, X.Y. Zhang, Z. Shen, H. Zhou, O. Abe, T. Nagai, Y. Tsutsumi, M. Chiba, J. Suzuki, Aeolian dust experiment on climate impact: An overview of Japan-China joint project ADEC, Global and Planetary Change, 52, 142-172, 2006.05.
42. Uno, I., K. Harada, S. Satake, Y. Hara, and Z. Wang, Meteorological characteristics and dust distribution of the Tarim Basin simulated by the nesting RAMS/CFORS dust model, Journal of the Meteorological Society of Japan, 10.2151/jmsj.83A.219, 83A, 219-239, 2005.02.