基于TVDI和气象数据的陕西省春季旱情时空分析

陕西省居于中国腹地,受干旱影响严重,开展遥感旱情监测工作,认识旱情的时空特征具有重要的现实意义。利用MODIS产品MOD11A2和MOD13A2构建NDVI-Ts特征空间,获取陕西地区温度植被干旱指数(Temperature Vegetation Dryness Index,TVDI),在利用土壤湿度和气象指数验证了TVDI反映旱情有效性的基础上,以TVDI为干旱指标分析了2000—2015年陕西省春季(2—5月)旱情的时空变化特征。结果表明:(1)土壤相对湿度和降水量与TVDI均呈负相关,TVDI对降水量存在一定的滞后性;(2)近16年来,陕西省年年有旱,但春季旱情总体呈逐年减轻的趋势,年内2—5月旱情会逐渐加重;(3)空间上,近16年来陕西省春旱较为严重的地区主要分布在陕北北部以及关中东北部,而陕北南部、关中西南部及陕南地区旱情较轻。

Spatiotemporal Variations of Spring Drought Based on TVDI and Meteorological Index in Shaanxi Province

Shaanxi is located in the hinterland of China where is vulnerable to the impacts of drought,it is significant to analyze the spatiotemporal variations of drought of Shaanxi Province.Based on temperature vegetation drought index (TVDI) obtained from the moderate resolution imaging spectroradiometer (MODIS) products (MOD11A2 and MOD13A2),we established the NDVI-Ts characteristic space.Based on TVDI that can reflect the degree of drought with the use of soil moisture data and meteorological indexes,we analyzed the spatiotemporal variation of spring drought in Shaanxi Province by using TVDI data.The results showed that:(1) there was the negative correlation between TVDI and soil moisture,and the negative correlation between TVDI and precipitation,and there was the time lag between the TVDI and precipitation;(2) in the past 16 years in Shaanxi Province,the tendency of drought severity descended,within a year,the tendency increased from February to May;(3) the arid region distributed in northern part of north Shaanxi and the northeastern part of Guanzhong Plain in the past 16 years,the drought of south Shaanxi area,the south of north Shaanxi and the southwestern part of Guanzhong Plain was relatively slight.