Abstract
The transport of dust aerosol in East Asia is affected by the East Asian winter monsoon (EAWM) and westerly circulation both for modern and geological periods. There are obvious seasonal changes in the intensity and range of EAWM and westerly jet; however, their impacts and relative contributions to East Asian dust transmission are still unclear. In this study, we use Regional Climate Model 4 (RegCM4) to simulate the changes in the East Asian dust cycle under present conditions, assessing the effects of EAWM and westerly jet on dust transport. The results show that the dust at the upper level is mainly transported by the westerly circulation, while that of the lower layer is mainly transported by the EAWM. In March, the westerly jet is located on the south side of the Tibet Plateau, and the high-level dust aerosol is transmitted eastward to the northern Pacific. Low-level dust is transmitted to the southeastern China with the influence of EAWM. With the northward shift of the westerly jet, the control range of the westerly winds increases in May and their correlations are weakened. In contrary, the impact of EAWM on the lower layer dust is enhanced. Due to the strengthened interaction between the westerly winds and the EAWM, they can both affect the middle-level dust transmission. The effect of EAWM is sensitive to the dust particle sizes. Under the action of EAWM, fine-grained dust is transmitted far away, while coarse-grained dust is limited to the vicinity of the source area. Once the dust is carried to the westerly layer, the influence of westerly winds on the transmission of different particle sizes dust is similar.
Highlights
Mineral dust, mainly from desert areas, is an important component of tropospheric aerosols (Ridgwell, 2002), and has a significant impact on air quality and human health
The transport of dust aerosol in East Asia is affected by the East Asian winter monsoon (EAWM) and westerly circulation both for modern and geological periods
The results show that the dust at the upper level is mainly transported by the westerly circulation, while that of the lower layer is mainly transported by the EAWM
Summary
Mainly from desert areas, is an important component of tropospheric aerosols (Ridgwell, 2002), and has a significant impact on air quality and human health. Investigations of East Asia dust deposition indicate that 30% of the dust in the atmosphere settles in the desert, 20% in the mainland China, and 50% transports to the Pacific and other places across long distances (Zhang et al, 1997). The Taklimakan Desert and the Gobi Desert are two major dust source areas in East Asia (Sun et al, 2001; Chen et al, 2014; Abulaiti et al, 2014; Lee et al, 2012; Li et al, 2012), which account for 70% of total Asian emissions (Zhang et al., 2003). The dust of Taklimakan Desert can be carried to higher than 5,000 meters and transported over long distances They are an essential source of aeolian sediments in the North Pacific (Shi and Liu, 2011)
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