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针对目前西北地区广泛存在的农业干旱问题,选取了新疆塔里木盆地北缘渭干河-库车河三角洲绿洲为研究区,选择云量较少的两幅TM影像,建立地表温度-植被指数特征空间。首先利用线性方程拟合了特征空间的上下边界,比较利用归一化植被指数(NDVI)建立的地表温度-植被指数特征空间Ts/NDVI和利用改进型土壤调整植被指数(MSAVI)构建的地表温度-植被指数特征空间Ts/MSAVI形状的差异,并计算得到两种温度植被干旱指数(Temperature vegetation dryness index—TVDI,分别为TVDIN和MTVDI)。对TVDI与同期野外不同深度的实测土壤重量含水量数据进行回归分析,建立TVDI估测土壤水分的经验模型并对模型进行验证。研究结果表明,TVDIN和MTVDI均能够反演表层土壤水分,其中MTVDI与土壤水分相关性比TVDIN与土壤水分相关性要高,MTVDI能够更好地反映区域土壤水分状况,是一种更有效的土壤水分监测方法,对农业干旱监测具有一定的科学依据。
In view of the widespread agricultural drought problem in Northwest China, this paper selected the Ogan River and Kuqa River delta oasis in northern margin of Tarim Basin as the research area, and selected two TM images with less cloud cover to establish the feature space of surface temperature-vegetation index . First, the upper and lower boundaries of the feature space were fitted by using linear equations. Ts / NDVI, which is established by normalized vegetation index (NDVI), and surface temperature, which was constructed by using improved soil adjustment vegetation index (MSAVI) - Ts / MSAVI feature space, and calculated two temperature vegetation dryness index (TVDI, TVDIN and MTVDI). TVDI and field depth of field soil moisture content data at different depths were analyzed by regression analysis to establish the TVDI empirical model of soil moisture and verify the model. The results show that both TVDIN and MTVDI can invert the surface soil moisture. The correlation between MTVDI and soil moisture is higher than that of TVDIN and soil moisture. MTVDI can better reflect the regional soil moisture status and is a more effective soil Moisture monitoring methods have some scientific basis for monitoring agricultural drought.