| In recent years,with the change in global climate and ecological environment,the climatic effects and environmental problems caused by dust discharged into the atmosphere have attracted much attention.East Asia is not only a region with a high incidence of global dust activity,but also an important source of the global dust cycle.However,the spatiotemporal variation of dust emissions in East Asia and its driving factors in recent decades have not been explored in detail.Therefore,based on the MERRA-2 dust emission dataset and multi-source remote sensing data,this paper explores the spatiotemporal characteristics and changing trends of sand and dust emissions in East Asia from 2000 to 2021.On this basis,using satellite assimilated data such as GLDAS and ERA5 and climate indices to explore the driving mechanism of surface and meteorological factors on dust emissions in East Asia.The main conclusions of the study are as follows:(1)The Taklimakan Desert,the Gurbantunggut Desert,the Turpan Basin,and the Gobi Desert in southern Mongolia and western Inner Mongolia are the main sources of dust emissions in East Asia Spring(March-May)is the season with the strongest dust emission in East Asia,while winter(December-February)is the period with the weakest dust emission intensity.Over the past 22 years,the dust emissions in the southwest of the Tarim Basin,the northern Junggar Basin and the northern Kumtag Desert showed a very significant increase trend.However,the dust emissions in the southwestern Tibetan Plateau,eastern Qinghai Province,northern Shaanxi Province,western Shanxi Province,south-central Gansu Province,and northern Mongolia showed a very significant downward trend.(2)There were obvious seasonal changes in the spatial distribution of atmospheric dust aerosol AOD in East Asia.The average AOD spatial distribution of seasonal dust aerosols shows that there were two high AOD centers and two low AOD centers in East Asia.The two high AOD centers were located in the northwestern and eastern regions of China,and the two low AOD centers were located in the Mongolian Plateau and the Tibetan Plateau.At the same time,the seasonal distribution of dust aerosol AOD revealed a dust belt from the dust source in East Asia to eastern China,the Korean Peninsula,Japan,and even further afield.Dust particles discharged into the atmosphere were mainly distributed in the middle and lower layers of the troposphere,especially in the 0-2km altitude layer.The upward transport height of dust in summer is much higher than in autumn and winter,and the concentration of dust in the lower atmosphere in spring and winter is much higher than in summer and autumn.(3)The lagged correlation between the average climate index of NAO and AO in winter and the spring dust emission in East Asia is significantly negative,and the intensity of dust emission in East Asia in different phases of coupling between AO/NAO in winter and the spring in the following year showed obvious differences.When the AO/NAO coupling was negative(positive),the East Asian trough and Siberian High were strengthened(weakened),the frequency of cold air activity increased(weakened),the regional wind speed strengthened(weakened),and East Asian emissions increased(decreased).In AO-/NAO+years,the Asian polar vortex was stronger to the south and the East Asian trough was stronger to the west.The Lake Baikal trough was in the deepening phase,which caused more polar cold air to move into East Asia,aggravating the intensity of dust activity.In the AO+/NAO-years,the Siberian High and East Asian trough weakened,which was unfavorable to the southward movement of cold air from Siberia.Therefore,the frequency of windy weather in East Asia decreased,partly weakening dust emissions.However,a positive geopotential anomaly in northeast China and a negative geopotential anomaly in South Asia triggered an anomalous enhancement in the easterly wind in the tropospheric area over northwest China.Strengthening of the Balkhash trough provides favorable conditions for gale weather in northwest China.The frequency of gale weather increased,and dust emissions were enhanced in northwest China.(4)In the univariate analysis,average wind speed,solar radiation,soil evaporative flux,air relative humidity,and snow cover can effectively explain the reasons for the variation of dust emission in East Asia.However,temperature,precipitation,soil moisture,and NDVI are difficult to explain the variation of dust emissions in East Asia.Multivariate analysis based on classification and regression trees showed that solar radiation was the dominant factor affecting the variation of dust emissions in East Asia,followed by average wind speed and relative humidity,and soil moisture and precipitation had relatively weak effects.When the solar radiation intensity is less than 159W/m~2,the relative humidity is less than 56.35%,the evaporation is greater than 16.47 W/m~2,the surface temperature is greater than 280.45K,and the soil humidity is less than 22.44kg/m~2,the combined structure is more conducive to the emission of dust in East Asia.However,the combined structure of solar radiation intensity below 159W/m~2,average wind speed below 3.23m/s,and precipitation above 1.4mm can effectively reduce the intensity of sand and dust emissions in East Asia. |
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