基于混合型线性双源遥感蒸散模型的南疆绿洲地区干旱研究

利用MOD16蒸散产品数据以及2001—2014年新疆气象站点数据,基于混合型线性双源遥感蒸散模型估算南疆绿洲地区地表蒸散,并对比验证MOD16蒸散产品、反演蒸散量与研究区气象站蒸发皿实测蒸发量之间的关系。定义了蒸散干旱指数EDI,计算EDI距平,分析绿洲地区干旱分布特点,同时对比降水距平来检验干旱监测的准确程度。结果表明:MOD16蒸散产品蒸散量、模型估算蒸散量与蒸发皿实测蒸发量数据的相关性较好,说明利用MOD16蒸散产品数据估算蒸散量可行,也说明估算的蒸散量可信度高;由于绿洲地区北部水分供应更充足,EDI值空间上由南至北呈减小趋势,EDI值年际变化明显且均大于0.6;EDI距平与EDI同向变化,与降水距平反向变化;南疆绿洲地区在2001、2007、2008、2009、2014年的EDI值大于0.66。因此,EDI距平定义了干旱轻重程度界限:EDI临界值为0.66;EDI值越大,EDI距平越大,降水距平越小,干旱程度越严重。

Analysis of drought in the oasis of Southern Xinjiang based on the hybrid linear dual source remote sensing evapotranspiration model

Evapotranspiration was estimated based on mixed linear dual source remote sensing model by using MODIS16 evapotranspiration product data and data of Xinjiang meteorological station from 2001-2014. This article compared the relationship between the MODIS16 evapotranspiration product data, the inversion evapotranspiration and the measured evaporation of the evaporating dish at the meteorological station in the study area. According to evapotranspiration, the evapotranspiration drought index (EDI) was defined, and the EDI anomaly was calculated to analyze the characteristics of drought distribution in the Oasis area. At the same time, the accuracy of drought monitoring was tested by comparing precipitation anomaly. The results showed that the evapotranspiration of MODIS16 products data and the evapotranspiration calculated by the model were highly correlated with measured evapotranspiration data, which indicated that it was feasible to estimate evapotranspiration by using MODIS16 evapotranspiration products data, and also revealed that the estimated evapotranspiration had high reliability. Moreover, as the water supply in the northern part of the Oasis was more abundant, the EDI value tended to decrease spatially from the south to north, and the inter-annual variation of EDI value was obvious and both were greater than 0.6. EDI anomalies changed in phase with EDI, and inversely changed with precipitation anomalies. In the Nanjiang Oasis area of Xinjiang, the EDI value of the five years in 2001, 2007, 2008, 2009 and 2014 was greater than 0.66. Therefore, the EDI anomaly defined the dryness and severity limit EDI value of 0.66. Finally, the larger the EDI value was, the larger the EDI anomaly was, the EDI smaller the precipitation anomaly was and the more severe the drought was.