Sand/dust storm processes in Northeast Asia and associated large-scale circulations
- ISSN: 16807324
- DOI: 10.5194/acp-8-25-2008
This paper introduces a definition of sand/dust storm process as a new standard and idea of sand/dust storm (SDS) groups a number of SDS-events in Northeast Asia. Based on the meteorological data fromWMO/GOS network, 2456 Chinese surface stations and NCEP-NCAR reanalysis, the sand/dust storm processes in Northeast Asia in spring 20002006 are investigated. And the evolutions of anoma- lies of general circulation in the troposphere are analyzed by comparing the spring having most and least occurrences of SDS in year 2006 and 2003. Associated with the notice- ably increased occurrence of SDS processes in spring 2006, the anomalies in 3-D structure of general circulation espe- cially in the mid-and high latitudes of the Northen Hemi- sphere (NH) are revealed. The transition period from the winter of 2005 to spring 2006 has witnessed a fast-developed high center over the circumpolar vortex area in the upper tro- posphere, which pushes the polar vortex more southwards to mid-latitudes with a more extensive area over the east NH. In spring 2006, there are the significant circulation anomalies in the middle troposphere from the Baikal Lake to northern China with a stronger southward wind anomaly over North- east Asia. Compared with a normal year, stronger meridional wind with a southward wind anomaly also in the lower tropo- sphere prevail over the arid and semiarid regions in Mongolia and northern China during spring 2006. The positive anoma- lies of surface high pressure registered an abnormal high of 410 hPa in the Tamil Peninsular make a stronger cold air source for the repeated cold air outbreak across the desert ar- eas in spring 2006 resulting in the most frequent SDS seasons in the last 10 years in Northeast Asia.