基于多源遥感数据的干旱监测研究

Drought Monitoring Based on Multisource Remote Sensing Data

及时准确地监测干旱可以预防其造成的农作物减产。归一化植被指数(NDVI)在监测植被生长状态、农业干旱方面都表现出了良好的特性。但NDVI对干旱的响应具有一定的滞后性。为了及时准确地监测旱情,本研究将热带降雨测量卫星(TRMM)的降雨数据与NDVI结合起来,构建了基于旬尺度的MNDVI干旱监测模型,并以吉林省农作物生长季为例,通过与历史数据、土壤湿度、叶面积指数(LAI)作相关性分析对其进行验证。结果表明:MNDVI监测的干旱变化图与历史记录有很好的吻合性,表明MNDVI监测干旱的准确性好;将MNDVI和NDVI分别与10 cm和20 cm土层的土壤湿度进行相关性分析,结果表明MNDVI在一定程度上可以消除NDVI监测干旱方面存在的滞后性;将MNDVI和降雨状态指数(PCI)分别与LAI进行时间序列分析,发现MNDVI与LAI有良好的一致性,而PCI与LAI没有一致性,表明MNDVI对植被的生长状态能够及时响应,可以用来监测农业旱情。

Monitoring drought accurately in time can prevent the reduction of crop yield caused by drought. The NDVI shows better characteristics in monitoring vegetation growth status and agriculture drought. But the response of NDVI to drought has a certain hysteresis. Therefore, we constructed the MNDVI based on ten day scale through combining the TRMM rainfall data with NDVI in this paper. In order to evaluate the accuracy and real-time performance, the MNDVI model was used to monitor the drought process in the crop growing season (from May to September) in Jilin Province in 2009, and the correlation analyses were conducted between MNDVI and the history data, 10-cm and 20-cm soil moisture and LAI. The results showed that the evolution process of drought monitored by MNDVI was in better agreement with historical data, which indicated that the MNDVI has better accuracy. The correlation analysis of MNDVI and NDVI with 10-cm and 20- cm soil moisture respectively showed that MNDVI could elimate the hysteresis of NDVI to a certain degree in monitoring drought. Through the time series analysis of MNDVI and PCI with LAI, we found the MVDVI had better consistency with LAI, while the PCI did not have. In conclusion, MNDVI could reflect the vegetation growth status in time, so it could be used for monitoring drought.