2010春季我国一次强沙尘暴过程分析

A severe sand-dust storm over China in the spring of 2010

2010年3月18～23日，一次强沙尘暴天气过程先后影响了我国21个省（区、市），影响范围约282×10^4km^2，2．7×10°人口遭沙尘天气侵袭。通过应用NCEP／NCAR2．5°×2．5°全球格点再分析资料，从沙尘暴爆发前后的天气形势、气象要素场的特征以及起沙和传输的动力机制等方面对这次沙尘暴过程进行初步分析。同时，利用每日空气污染指数资料和北京能见度资料，分析了沙尘暴期间全国空气污染物浓度的分布和北京地区能见度的变化。结果表明：这次沙尘天气分两个阶段，第一阶段为3月18～21日，第二阶段为3月21～23日，从影响范围及强度方面来说，第一阶段沙尘过程强于第二阶段。蒙古气旋强烈发展是引发此次沙尘暴的主要原因。沙尘暴基本沿西北到华北，华北到华南的路径传播。空气污染指数及能见度变化基本反映了此次沙尘暴的移动路径和强度变化。此次沙尘暴天气的沙尘源地位于蒙古国南部以及中国的新疆南部、东部和内蒙古中西部地区。由于热力和动力（涡度）两种因子的联合作用，使地面气旋一面向前移动，一面加深发展，高空槽因冷平流加深，并因涡度平流而向前移动。冷锋锋生加强，产生大风天气，是引发沙尘暴和推动沙尘长距离输送的动力因子。

From March 18 to March 23,2010, a severe sand and dust storm affected the 21 provinces over China covering nearly 2.82 million square kilometers, and impacted 270 million people. The sand dust storm is the most strongest one since 2006. By using NCEP/NCAR （2.5° × 2.5° ） reanalysis data, a preliminary analysis of this severe sand-dust storm was conducted in this paper based on the weather situation, the vertical and horizontal distribution characteristics of some key meteorological parameters, the dynamic and thermal conditions which induced strong up- ward motion, and dynamic mechanism that sand-dust was blown and raised during the dust storm. The distribution of air pollutants concentration near the ground and visibility variation were also analyzed based on the observed air pollution index （API） data of China and visibility data of Beijing. The sand-dust storm could be divided into two stages, the first stage was from March 18 to March 21, the second stage was from March 21 to March 23. The sand-dust storm in the former stage was stronger than that in the later stage in terms of strength and range of influ- ence. The severe sand-dust storm was mainly caused by strong development of Mongolian cyclone. The route of the sand-dust storm was from northwest of China to north of China, then from north of China to the east and south of Chi- na. The movement route and the intensity variation of the sand-dust storm were clearly envailed by the time series data of API and visibility observed in Beijing. The primary sand-dust sources were from southern Mongolia, south- ern and eastern Xinjiang, and the west and middle of Inner Mongolia in China. With the interaction of thermal and dynamic factors （the intensive thermal advection and vortex advection）, the Mongolia cyclone was developed quick- ly, moving torward east and then southeast. The altitude trough at 500 hPa level was gruadually deepened due to cold temperature advection and moved forward due to vortex advection. Generally saying, the Mogolia cyclone and cold front were the main dynamic factors which induce the sand-dust storm and carry out long distance transportation of dust. In this paper, some critical thermal and dynaic mechanisms were identified for the sand-dust storm that wolud be sound basic perspectives to simulate the sand-dust storm process in the next step.