塔里木盆地一次“东灌”沙尘暴大气边界层特征

Characteristics of Atmospheric Boundary Layer during an East Irrigated Sandstorm in Tarim Basin

利用探空、NCEP/NCAR1°×1°再分析资料、地面气象站观测资料,对新疆塔里木盆地2014年10月28—29日的沙尘暴天气过程前、中、后大气稳定度、混合层厚度、风、温、湿廓线等边界层特征量进行分析。结果表明:此次天气过程为欧洲脊东移,推动西西伯利亚低槽快速进入北疆地区,随后东移翻越东天山进入南疆,造成“东灌”沙尘暴天气;沙尘暴造成边界层特征量表现为K指数减小,沙氏指数增大,理查逊数减小,混合层厚度降低等特征;风向由偏西风转为偏东风,风速则在静风转为30m/s的偏东急流;温度为沙尘暴之前为贴地逆温,之后大气混合比较均匀,相对湿度为先增加后减小,沙尘暴天气是一个降温增湿的过程,边界层风、温、湿廓线都打破了原有分布规律;沙尘暴过程是大气不稳定层结变为稳定层结的过程。

Based on the sounding data, NCEP reanalysis data and meteorological observation data in Xinjiang, The characteristics of boundary layer such as atmospheric stability, mixed layer thickness, wind, temperature and wet profile before and after the sandstorm weather process were analyzed during October 28th to 29th, 2014 in Tarim Basin. The results show that, European ridge eastward in 500 hPa, pushed the West Siberia trough into northern Xinjiang area and then moved eastward across the eastern Tianshan Mountains into Tarim Basin, caused this east irrigation sandstorm. The characteristics of the boundary layer caused by sandstorms showed that the K index, Richardson number and the thickness of the mixed layer decreases while the SI index increases. The wind shifted from westerly wind to easterly wind, while the wind speed shifted easterly jet to 30 m/s from calm wind. The temperature was inversion before the sandstorm, and then the atmosphere was mixed evenly. The relative humidity was increased first and then decreased. The sandstorm weather was a process of cooling and humidifying. The wind, temperature and wet profile of the boundary layer have broken the original distribution. The sandstorm process make the unstable layer of the atmosphere become a stable layer.