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

---

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

---

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

Reiji Kimura Masao Moriyama Levent Saylan

出版者

公益社団法人 日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.19, pp.94-100, 2023 (Released:2023-05-26)

参考文献数

39

---

Simulations of future climate indicate that the Mediterranean countries will see increasing temperatures, and decreasing precipitation. In Türkiye, which has a semi-arid and dry sub-humid climate, the coupled effect of warming and drought is expected to lead to a general increase in aridity. We applied indices derived from satellite data to provide continuous monitoring for drought hazards and evaluated recent trends in aridification and drought. Annual averaged temperatures showed a statistically significant rise, although annual rainfall showed no nationwide trend despite strong fluctuations over Türkiye. Significant increasing (decreasing) trends of vegetation (aridification) could be found in the northern, western, and southern regions, despite the rising temperatures and fluctuations in rainfall. One cause of these trends is presumed to be an increase in the nation's proportion of forest, orchard trees, and irrigated farmland. Although decreasing trend of aridification over Türkiye, drought has recurred throughout the 22-year study period in the central and eastern regions. These areas in which the annual averaged satellite-based aridity index exceeds a threshold value correspond closely to regions vulnerable to drought. Satellite-based indices may show particular promise for the major agricultural or pasture areas in central and eastern Türkiye, which are at heightened risk of future drought.