2008年冬—2009年春辽宁省干旱的遥感监测与大气结构分析

Remote Sensing Monitoring and Atmospheric Structure Analysis of the Drought in Liaoning Province from Late 2008 to Early 2009

MODIS的多波段及高时空分辨率特征有利于对大面积干旱区域的动态监测。2008年10月下旬至2009年2月中旬我国中东部和北方地区十多个省市遭遇了严重干旱。论文选取2009年初干旱较严重的辽宁省作为研究区域,使用热惯量法提取MODIS数据的干旱信息,识别出干旱区域和干旱程度。为了深入分析导致此次干旱的大气结构特征和机理,从天气形势、斜温图(Skew-T)两方面揭示了干旱发生期间影响旱区的大气风向风速、温度、湿度及大气能量的结构特征。研究表明东北冷涡强大稳定而导致的干冷空气路径维持,整层大气的温度-露点差较大,西北风使来源地水汽稀少,稳定的大气层结及干下沉气流等大气结构特征是引起辽宁省严重干旱的重要原因。

MODIS has the advantages of multi-band, high spatial and temporal resolution, which are propitious to the dynamic monitoring of a large area of arid regions. During late October 2008 and mid-February 2009, more than 10 provinces in east-central and northern China were hit by the severe drought. In this paper, Liaoning Province suffered the serious drought in early 2009 is selected as a study area. The drought information in MODIS data is extracted through the thermal inertia model, which is used to distinguish the range and the degree of the drought. In order to make a deep analysis of atmospheric structure characteristics and mechanism which led to this drought, wind direction, wind velocity, temperature, humidity and structure characteristics of atmosphere energy during this drought are revealed from two aspects： weather situation and Skew-T diagrams. The results show the main reason for this drought is the abnormal atmospheric structure, including the maintenance of dry cold air path caused by the strong and stable northeast cold vortex, the large temperature-dew point difference of the whole troposphere, the little water vapor in source area because of the northwest wind, the stable stratification and dry sink of atmosphere.