Elevated large-scale dust veil originated in the Taklimakan Desert: intercontinental transport and 3-dimensional structure captured by CALIPSO and regional and global models
1Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan
2National Institute of Aerospace, Hampton, VA, USA
3National Institute for Environmental Studies, Tsukuba, Japan
Abstract. An intense dust storm occurred during 19–20 May 2007 over the Taklimakan Desert in northwestern China. In the following days, the space-borne lidar CALIOP tracked an optically thin, highly elevated, horizontally extensive dust veil that was transported intercontinentally over the eastern Asia, Pacific Ocean, North America, and Atlantic Ocean. A global aerosol transport model (SPRINTARS) also simulated the dust veil quite well and provided a 3-D view of the dust intercontinental transport. The SPRINTARS simulation revealed that the dust veil travels at 4–10 km altitudes with a thickness of 1–4 km along the isentropic surface between 310 K and 340 K. The transport speed is about 1500 km/d. The estimated dust amounts exported to the Pacific is 30.8 Gg, of which 65% is deposited in the Pacific and 18% is transported to the North Atlantic. These results imply that the dust veil can fertilize the open oceans, provide background dust to the atmosphere remote from the sources.
The entrainment mechanism that injects dust particles into the free atmosphere is important for understanding the formation of the dust veil and the subsequent long-range transport. We used a regional dust transport model (RC4) to analyze the dust emission and entrainment over the source region. The RC4 analysis revealed that strong northeasterly surface winds associated with a low pressure invade into the Taklimakan Desert through the east side corridor and form a strong up-slope wind along the high and steep mountainside of the Tibetan Plateau, blowing up large amounts of dust into the air. The updraft further brings the lofted dust particles up to the free troposphere (about 9 km MSL) where the westerly generally blows. The peculiar terrain surrounding the Taklimakan Desert plays the key role in the entrainment of dust to the free troposphere to form the dust veil.