Atmos. Chem. Phys. Discuss., 7, 9259-9281, 2007
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Sand/dust storms over Northeast Asia and associated large-scale circulations in spring 2006
Y. Q. Yang, Q. Hou, C. H. Zhou, H. L. Liu, Y. Q. Wang, and T. Niu
Centre for Atmosphere Watch {&} Services (CAWAS), Chinese Academy of Meteorological Sciences, China Meteorological Administration (CMA), Beijing 100081, China

Abstract. This paper presents a study on the meteorological conditions that accompany the sand/dust storms (SDS) of East Asia in spring 2006, based on the SDS data collected both by WMO during 2000–2006 and by 2456 Chinese surface stations, and on the meteorological reanalysis data from NCEP-NCAR . The evolution of 3-D structures of the general circulations prevailed in both winter and spring as well as their annual anomalies were investigated by comparing the years having most and least occurrences of SDS between 2000 and 2006. It is found that spring 2006 featured a noticeably increased occurrence of SDS, compared with previous years. The general circulations prevailed through both winter and spring, especially the 3-D structure of the polar circulation, show the significant anomalies compared to a normal year. This produced a range of corresponding weather phenomena, including circumpolar vortices at the upper troposphere, mid-level westerly jets, and lower zonal winds, which all favored the SDS production and transport in 2006. The study also reveals a fact that comparing with a normal year, the transitional period from the winter of 2005 to the spring of 2006 has witnessed a fast-developed high center at the upper troposphere of the northern hemisphere and the circumpolar vortex area, which pushes the area dominated by the circumpolar vortices further to mid-latitudes. The circumpolar vortices shifted southwards, and prevailed over an extensive area across the northeast hemisphere for a sustained period. The mid-high latitude areas that sit in the south of the circumpolar vortices in Asia have experienced significantly abnormal westerly jets at the mid-level of troposphere. Zonal winds prevailed at the mid and lower levels of troposphere. Sea level pressure registered an abnormal high at 4–10 hPa, compared with a normal year. The above-mentioned 3-D structures of general circulation have created thermal and dynamic conditions that favor the repeated genesis and momentous development of the Mongolian cyclones, which in turn contributes to the frequent occurrences and long distance transport of SDS.

Citation: Yang, Y. Q., Hou, Q., Zhou, C. H., Liu, H. L., Wang, Y. Q., and Niu, T.: Sand/dust storms over Northeast Asia and associated large-scale circulations in spring 2006, Atmos. Chem. Phys. Discuss., 7, 9259-9281, doi:10.5194/acpd-7-9259-2007, 2007.
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