塔里木盆地局地和区域性强沙尘暴天气过程研究

A Study on the Local and Regional Strong Sandstorm Process in Tarim Basin

利用1961—2001年塔里木盆地周边地区43站沙尘暴资料,给出了塔里木盆地局地、区域性强沙尘暴天气过程的定义,得到局地和区域性强沙尘暴天气过程1423次和385次,分析了沙尘暴天气过程的时空分布特征和变化原因,并根据地面冷高压和沙尘暴天气的移动路径对385次区域性强沙尘暴天气过程进行普查分析。结果表明:塔里木盆地局地沙尘暴天气过程的高发中心位于柯坪和民丰,区域性强沙尘暴天气过程集中在塔里木盆地南缘的莎车至且末一线和柯坪,柯坪和民丰是盆地沙尘暴的多发中心;区域性大风天气过程的减少、年平均降水量的增加和年平均气温的升高是塔里木盆地区域性强沙尘暴天气过程趋于减少的重要原因;局地沙尘暴天气过程主要出现在3～9月;区域性强沙尘暴天气过程,集中在4～6月,春季4～5月是连续性多暴发时段,造成区域性强沙尘暴天气过程的冷空气以西进、东灌和西进加东灌为主要路径,盆地热低压的作用不可忽视。

By using the sandstorm data observed at 43 weather stations from 1961 to 2001 around the edges of Tarim Basin, the climatic character of local sandstorm process and regional strong sandstorm process happened within 41 years in the basin is analyzed. The regions around Tarim Basin include Hotan Administrative Offices, Kashi Administrative Offices, Kizilsu Kirgiz Autonomous Prefecture, Aksu Administrative Offices, Bayangol Mongol Autonomous Prefecture and Turpan Administrative Offices. If sandstorm appears at one station in every day during a sandstorm process, it is defined as a local sandstorm process (LSP); if sandstorm appears at eight or more stations in every day, it is defined as a regional strong sandstorm process(RSSP).\;The accumulative total days of local sandstorm in the basin from 1961 to 2001 are 1785, the accumulative total times of LSP are 1423. The accumulative total days of regional strong sandstorm in the basin are 545, the accumulative total times of RSSP are 385.\;LSP happened all the year round, concentrated in the months from Mar. to Sept. with the largest frequency in July, and mainly lasted within one day. The LSP in the basin accounted for 5% to 10% of the total sandstorms, two notable centers located in Kalping to the north\|west part of the basin and Minfeng to the south part of the basin. The number of LSP in 1960s was the same as that in 1980s, was the least in 1990s.\;The RSSP lasted chiefly one or two days, concentrated from Apr. to June with a largest frequency in May. In Apr. to May of spring, the RSSP was not only frequently happened but also lasted a longer time. The RSSP appeared around the edges of Tarim Basin, accounted for 30% to 50% of the total sandstorm in the basin, mainly happened in Shache, Pishan, Hotan, Qira, Minfeng and Qiemo to the south part of the basin and Kalping to the north\|west part of the basin. It can be deduced that 40% to 60% of the sandstorm in the basin are ordinary sandstorm processes (sandstorm happened within 2 to 7 stations ).\;Kalping and Minfeng are the centers where sandstorm happened frequently in Tarim Basin. The sandstorm in Kalping is related with the local weather system and underlying surface; the weather systems from east and west often meet at Minfeng, which makes Minfeng become the center of sandstorm at the south edge of the basin.\;The number of RSSP in the basin reduced obviously from 1960s to 1990s, it was the least in 1990s, the number in 1990s was less than 30% of that in 1960s. The important causes for the reduction of the number of RSSP in the basin were the reduction of regional strong wind process, the increase of annual average precipitation and the rising of annual average temperature.\;The north cold air mainly came from the east, the south cold air chiefly entered from the west, both of them caused the RSSP in Tarim Basin. The RSSP in the basin was chiefly caused by thermal depression and the cold air which entered the basin from west, or east, or both west and east.