应用FY-2地表蒸散产品监测西南特大干旱

基于能量平衡原理的卫星遥感地表蒸散产品具有清晰明确的物理含义,广泛地应用于遥感干旱监测领域。本研究以中国能量与水平衡监测系统（CEWBMS）和近11年的静止卫星遥感数据集为基础,利用FY-2/VISSR数据生成相对蒸散距平百分率（Percentage of Relative Evapotranspiration Anomaly,PRETA）产品,应用于全国范围的旱情连续监测。与极轨卫星同类产品相比,基于FY-2的PRETA产品在监测范围和频次上都具有明显的优势。由于距平百分率的引入,PRETA干旱指数等级划分不再与季节和地域气候类型等因素相关。针对2009年秋季至2010年春季西南大旱的监测结果进行了对比分析和统计,结果表明PRETA干旱指数真实客观地反映了旱情时空变化,面平均的PRETA和降水距平百分率时间序列变化趋势显示出良好的一致性,PRETA与10 cm土壤相对湿度有较高的相关性。本研究为实时、大范围、高分辨率、定量和动态卫星遥感监测干旱提供了切实可行的方法。

Using FY 2 Based Evapotranspiration Index to Monitor the Severe Drought in Southwest China

Satellite based evapotranspiration according to the energy balance principle has clear physical meaning, and is widely used in the field of remote sensing for drought monitoring. Based on the China Energy and Water Balance Monitoring System (CEWBMS) and long time series (11 years) dataset of geostationary satellite, the percentage of relative evapotranspiration anomaly (PRETA) is obtained by using FY 2/VISSR remote sensing data and investigated for large area drought monitoring. Compared with polar orbiting satellite based drought indices, the FY 2 based PRETA drought index has obvious advantages in the scope and frequency of monitoring. Due to the introduction of anomaly to relative evapotranspiration, the drought intensity classification is no longer dependent on seasonal and regional variations. Continuous quantitative evaluations of drought conditions in Southwest China from autumn 2009 to spring 2010 are carried out and statistics of the arid area are collected. Results show that spatial and temporal changes of drought status derived from PRETA are highly correlated with the actual drought situations. Trends of the area averaged PRETA and the precipitation anomaly percentage time series are highly consistent. Meanwhile, PRETA has a reasonable correlation with 10 cm relative soil moisture measurements. On the whole, the drought monitoring application in this study provided a practical way for real time, large area, high spatial resolution, quantitative and dynamic monitoring of drought.