200hPa高空急流与宁夏春季沙尘暴过程的特征分析

Relationship between 200 hPa Jet and Sandstorm during Spring in Ningxia

利用NCAR/NCEP全球再分析资料,首先分析了1955年到2003年宁夏春季沙尘暴过程与200 hPa急流的关系,发现2月、3月200 hPa的U、V风场与宁夏春季沙尘暴关系密切。然后对1970—1999年66次宁夏强和特强沙尘暴过程发生前200 hPa急流的演变情况进行了分析,结果表明:宁夏强和特强沙尘暴过程发生前后,高空急流主要表现为3种类型:一是西风急流型;二是副热带急流型;三是西风急流与副热带急流振荡合并型。最后以2001年4月8日宁夏特强沙尘暴天气过程为例,对其发生前后高空急流演变与沙尘暴落区、垂直环流特征及其对沙尘暴的作用进行了分析和探讨,得到了一些新的启示。

The relationship between 200 hPa jet and sandstorm in Ningxia in spring from 1955 to 2003 was analyzed by using NCAR/NCEP reanalyzed data. Results showed that the U, V fields at 200 hPa in March and April are significant to spring sandstorm in Ningxia. The evolution of 200 hPa jet was studied during 66 cases of severe and very severe sandstorms during 1955-2003 in Ningxia. Results show that there are 3 types of jet pattern： westerly jet, subtropical jet and combination of westerly and subtropical jet. A case study was conducted on a sandstorm event occurred on April 8, 2001. Its jet evolution, vertical circulation and their impact on sandstorm were analyzed and some new clues were concluded.