摘要
通过分析塔里木盆地沙漠的风积地貌,结合近40年气象站的风况观测资料,探讨了沙尘暴形成的大气环流特征.研究结果表明,从天气学理论上来看,降水和沙尘暴天气相伴而生.在年际时间尺度以上,沙尘暴发生日数与降水存在显著的负反馈机制.然而降水抑制沙尘暴发生的理论无法解释在月际尺度内降水与沙尘暴呈正相关的事实.通过分析云量、沙尘凝结核以及卫星计算的云滴有效半径表明,由于沙尘气溶胶可以长时间悬浮在大气中并作为凝结核,使云中的水汽分布到更多的粉尘颗粒中,导致空中云滴有效半径剧减而无法达到形成降水的阈值,从而抑制降水的产生.这从理论上可以很好地解释上述矛盾,为解释降水和沙尘的互反馈机制提供了新的理论.
The characteristics of atmospheric circulation when dust storms occurred was discussed by analyzing the data of prevailing wind,direction observed at the 25 surface stations for about 40 yearS and the Taklimakan Desert＇s shapes of dune which could show the prevailing wind direction in the Tarim basin during dust storm period. The mechanism to form dust storm and precipitation was almost same according to the principle of synoptic meteorology, namely, the dust storm and precipitation could occur simultaneously in theory. But, in inter-annual and longer time scale, there was a significant negative feedback mechanism between the number of dust storm days and precipitation. It was reverse compared with the positive feedback mechanism from the principle of synoptic meteorology. The theory that precipitation suppresses dust storm occurring might explain these facts that the negative relationship between the number of dust storm days and precipitation in hater-annual and long time scale, but could not explain the observed fact that the relationship was positive in mofithly scale. By analyzing the cloud coverage, dust condensation nucleus and cloud drop effective radius from the Aqua satellite data, a mass of dust aerosol as condensation nuclei effectively caused the reduction of cloud drop effective radius to fail to reach the threshold and thus suppressed the preciPitation. The theory may be a good explanation of the above-mentioned logic,contradiction and provides a new view of the mechanism of feedback between precipitation and dust aerosol.
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2008年第2期102-106,共5页
China Environmental Science
基金
国家自然科学基金资助项目(40675053)
国家“973”项目(2005CB422000)
干旱基金(IAM200714)
关键词
塔里木盆地
沙尘凝结核
云滴有效半径
沙尘暴
Tarim basin
dust condensation nuclei
cloud drop effective radius
dust storm period
precipitation
