著者

Kei Kawai Hitoshi Matsui Reiji Kimura Masato Shinoda

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.239-245, 2021 (Released:2021-12-18)

参考文献数

41

被引用文献数

4

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The emission of Asian dust in arid regions of East Asia is controlled by many land surface parameters such as snow cover, soil moisture, and vegetation. In climate models, these factors are represented by the threshold friction velocity u*t, but its treatment has large uncertainties. Here we show that the treatment of u*t is important for estimating the emissions, transport, and climate impacts of Asian dust. Our global aerosol model simulates dust event frequencies that better agree with observations in East Asia when u*t over a smooth surface is changed from the default value of 0.23 m s−1 to an observation-based value of 0.40 m s−1. Also, seasonal Asian dust emissions become more variable, increasing by 31% in spring and decreasing by 46% in summer and fall, and the annual amounts of Asian dust transported and deposited over the North Pacific (Arctic) increase by 43% and 49% (130% and 73%), respectively. Our results demonstrate that better representation of u*t in climate models is necessary to improve estimates of the emissions and transport of Asian dust and better understand its roles in the Earth system, such as its interactions with radiation, clouds, snow/ice albedo, and land and ocean biogeochemistry.

著者

Kei Kawai Hitoshi Matsui Reiji Kimura Masato Shinoda

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-042, (Released:2021-11-02)

被引用文献数

4

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The emission of Asian dust in arid regions of East Asia is controlled by many land surface parameters such as snow cover, soil moisture, and vegetation. In climate models, these factors are represented by the threshold friction velocity u*t, but its treatment has large uncertainties. Here we show that the treatment of u*t is important for estimating the emissions, transport, and climate impacts of Asian dust. Our global aerosol model simulates dust event frequencies that better agree with observations in East Asia when u*t over a smooth surface is changed from the default value of 0.23 m s−1 to an observation-based value of 0.40 m s−1. Also, seasonal Asian dust emissions become more variable, increasing by 31% in spring and decreasing by 46% in summer and fall, and the annual amounts of Asian dust transported and deposited over the North Pacific (Arctic) increase by 43% and 49% (130% and 73%), respectively. Our results demonstrate that better representation of u*t in climate models is necessary to improve estimates of the emissions and transport of Asian dust and better understand its roles in the Earth system, such as its interactions with radiation, clouds, snow/ice albedo, and land and ocean biogeochemistry.

著者

Kei Kawai Yuta Nishio Kenji Kai Jun Noda Erdenebadrakh Munkhjargal Masato Shinoda Nobuo Sugimoto Atsushi Shimizu Enkhbaatar Davaanyam Dashdondog Batdorj

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.52-56, 2019 (Released:2019-03-07)

参考文献数

21

被引用文献数

4

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Asian dust is transported over a long range via the mid-latitude westerlies when dust is lifted to the free troposphere over the source regions, whereas dust remaining in the atmospheric boundary layer is not transported far. In the Gobi Desert, a major source region of Asian dust, a ceilometer (compact lidar) monitors the vertical distribution of dust at Dalanzadgad, Mongolia. On 29-30 April 2015, the ceilometer observed a developed dust storm over the ground, followed by a dust layer within a height of 1.2-1.8 km. The dust storm had already developed in the upwind region before reaching Dalanzadgad. This feature was also shown in the ceilometer observation data. The dust layer remained at almost the same height for 12 h, because the dust became trapped within an inversion layer at a height of 1.2-1.5 km over cold air. This result suggests that the inversion layer prevented the dust from reaching the free troposphere, thereby restraining the long-range transport of the dust via the westerlies. This is the first paper that reports this type of vertical distribution of dust in the source region based on observation data.

著者

Masato SHINODA

出版者

The Association of Japanese Geographers

雑誌

Geographical review of Japan, Series B (ISSN:02896001)

巻号頁・発行日

vol.69, no.2, pp.170-184, 1996-12-01 (Released:2008-12-25)

参考文献数

87

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The present review paper outlines the state of the art of recent observational studies conducted by Japanese Climatologists on global- to synoptic-scale precipitation in terms of its spatial pattern, seasonal change, and interannual/interdecadal variability. In recent investigations, concerns have been extended to the global scale, while special attention has been focused on the Asian/Australian monsoon regions and their surroundings. That is, the longitudinal band from Central Asia/India in the west, to East Asia/Australia in the east. The interannual and interdecadal variability of Asian rainfall has been studied in relation to the El Niño/Southern Oscillation (ENSO) phenomenon, western Pacific/Indian Ocean sea surface temperatures (SSTs), Eurasian snow cover, and their associated atmospheric circulations. The First Global Atmospheric Research Program (CARP) Global Experiment (FGGE), performed during December 1978-November 1979, promoted a deeper understanding of the spatial and seasonal distribution of precipitation on time scales shorter than one month, as well as precipitation-producing circulation mechanisms. Satellite data derived from NOAA and geostationary meteorological satellite (GMS) of Japan have been widely used for examining the spatial pattern and seasonal change of satellite-inferred precipitation, mainly over oceanic areas centered in the western Pacific. Recommendations are given for future studies and programs in this field, from the aspects of the long-term monitoring of the Asian monsoon variability and the understanding of climate dynamics linked with precipitation.