2002年和2003年春季中国沙尘暴形成和输送的对比分析

2002年春季中国华北和东北发生了数场强沙尘暴天气.而2003年春季沙尘暴发生次数较少且强度也弱.为了解这两年沙尘暴差异的原因,作者用NCEP/NCAR再分析资料对两年中3、4月份候距平进行了分析.从侯距平图可看出,2002年负距平区主要位于华北和东北,并与发生大范围沙尘暴天气的区域相吻合,这与东亚大槽的发展与演变有关.在2003年高度场的距平图中,高度场的负侯距平多位于我国西部,这是因中纬度长波槽是在西部地区发展形成的.从月平均风资料分析,2002年风速大于6 m s-1的区域也与强沙尘暴区一致.2003年两个月中,我国大部地区风速都偏小.虽然2003年4月在东北有大于6 m s-1的风区,但不在我国主要的沙漠化地区.通过对大气环流及地表参数的分析,作者认为沙尘暴的易发地区多是干旱与半干旱地区,植被的生长能力弱;在降水没有比常年显著增加并使地面植被生长有明显改善的情况下,大气动力因素相对地面参数而言是主导沙尘暴年际变化的主要因子.

Comparison of Forming and Transportation of Dust Storm between 2002 and 2003 in China

A number of strong dust storms occurred in North China and Northeast China in the spring of 2002, but only a few weak dust storms in the spring of 2003 occurred. In order to understand the difference between 2002 and 2003, the pentad anomaly of height in March and April during the two years was analyzed with NCEP/NCAR reanalysis data. On pentad, the negative height anomaly was located in North China and Northeast China, it was uniform with the field where the strong dust storms occurred, and was probably associated with the development and evolution of East Asian trough at 500 hPa. The negative height anomaly was mostly located in the wertern part of China on the height anomaly field in 2003. It may be caused by long wave trough in the middle latitude. The results show that the area of wind speed exceeding 6 m s -1 in 2002 tallies with the field of strong dust storm in terms of monthly average wind data. The wind velocity is smaller in spring of 2003. Even though, there was area where wind velocity is over 6 m s -1 in Northeast China, it was not located in desert. By analysis of atmosphere circulation and surface parameter, the atmosphere dynamic factors were the main reason that caused the differences of dust storms between 2002 and 2003 rather than the surface factors.