Long-range transport of Saharan dust to East Asia and their regional impacts

Abstract

Saharan dust accounts for about 50-60% of the total global dust and can affect regional climate, environment and ecosystems through direct and indirect effects. However, the long-range transport of Saharan dust to East Asia and the further specific effects on its weather and climate are still poorly understood. Using the satellite observations combined with the model simulations, the multiple reanalysis data and HYSPLIT trajectory analysis, we systematically study the long-range transport of Saharan dust to East Asia and further study the impact of Saharan dust on the direct radiative forcing, clouds and precipitation in East Asia. A quarter (24.3 ± 6.2%) of dust cases in East Asia were originated from the Sahara Desert. The long-range transported Saharan dust is usually located in the upper troposphere of East Asia. The total annual average amount of Saharan dust transported over East Asia is 33.05 ± 9.78 Tg/year. Saharan dust can be transported eastward throughout the year and contributes about 35.8% of the dust to the upper troposphere in northern China in spring, which is almost equivalent to the amount of dust lifted from the East Asian dust source. Furthermore, in terms of regional impact, Saharan dust has a cooling effect on the surface and the top of the atmosphere, and a heating effect on the atmosphere. During a rainfall event, Saharan dust reduces the cloud supercooled water path over the Taklimakan Desert by 13.3 g/m2 in 3 h, converting supercooled water clouds into ice clouds and increasing the cloud ice-water path. As a result, a large amount of dust that acts as ice nuclei induces rainfall in the hinterland of the Taklimakan Desert as high as 6.32 mm. This study provides a new perspective on the important role of Saharan dust over East Asia, contributes to a better understanding of its long-range transport properties over East Asia and the sources of dust aloft in East Asia, and elucidates the impact of long-range transported dust on regional direct radiative forcing, clouds, and precipitation to better assess the impact of dust on climate and environment.