宁夏中北部春季沙尘暴与气候及环流背景关系的研究

本文利用1961-1999年宁夏中北部有代表性的5站的地面观测资料及NCEP资料,分析了宁夏中北部春季各月沙尘暴与气候及环流背景的关系。结果表明:春季3、4月宁夏中北部的沙尘暴天气发生频数与其前冬的气温呈显著反相关关系,而冬季气温对5月份宁夏中北部沙尘暴天气的发生频数影响并不显著。而3、4月份宁夏中北部春季沙尘暴发生频数与我区上游沙源区的地面低压系统发生的频数与强度密切相关。

Studies on the Relationship Between Spring Sandstorm in Middle and North Ningxia and the Background of Climate and General Circulation

In the paper, by using surface observation data from five stations in north and middle Ningxia and NCEP data in 1967-1999, the relationship between the frequency of sandstorm occurredin middle and north Ningxia in spring and the background of climate and the general circulation is analyzed. The results show that there is the positive correlationbetween the mean temperaturein last winter and the frequency of sandstorm in March and April; the frequency of sandstorm in march and April are closely related to the low pressure system in sand-dust source areas. There is positive correlationbetween the frequency of sandstorm and the mean temperatureat 850hPa in the zone 100-110E,30-35 N in March; but there is negative correlationbetween frequency of sandstorm and the mean temperatureat 850hPa in the zone 100-110 E,45-50 N in May. It shows that the occurrence of sandstorm in north china include Ningxia in early spring(March) is related to lower latitude circulation. There was positivecorrelation between sandstorm frequency and the latitudinalwind speed at 500hPa in north china in April and May. Compareing the correlation between climate and general circulation background in each month in spring, they have different feature in every month in spring. It also shows there are differences of the effect of low and high latitude circulation element for sandstorm in middle and north Ningxia in each month in spring.