MODIS和降尺度TM数据反演叶面积指数相互验证中几何处理方法的研究

提出了利用MODIS产品中的几何信息,把经过几何校正的TM数据反演叶面积指数(LAI)模拟成具有MODIS成像几何的降尺度LAI,然后与MODIS数据反演LAI进行对比验证的几何处理方法.以江西千烟洲研究区为例,采用经验公式反演TM和MODIS数据以获得两个尺度的LAI图像,分别用本文提出的新方法和传统方法进行尺度转换和对比验证.由反射率和LAI散点图得:新方法能显著提高TM降尺度图像与MODIS对应区域图像像元的对应精度.并且,新方法对大倾角观测MODIS图像与TM图像之间像元对应关系的改善更明显.因此,本文提出的几何处理方法可以建立不同尺度的遥感数据间更为准确的像元对应关系,更适用于不同尺度遥感数据反演产品的相互验证.

A STUDY ON GEOMETRICAL PROCESSING METHODS FOR LAI PRODUCTS INTERCOMPARISON BETWEEN MODIS AND TM

There is a new geometrical processing method to simulate MODIS imaging using the LAI map which is derived from a geo-corrected TM map and empirical expressions,and the geometrical information such as observing zenith angle,observing azimuth angle,longitude and latitude of Level-1B MODIS products for intercomparison of the LAI products from MODIS and TM data.It has been tested in Qianyanzhou forest,Jiangxi province,China,and compared with a traditional geometrical processing method on the assumption that the corresponding ground area of any MODIS pixel is rectangular.With the same empirical relationship to retrieve LAI map from MODIS and TM data of Qianyanzhou,it is found that the new method significantly improves the correlation between MODIS LAI and TM LAI compared to the traditional geometrical processing method.Furthermore,the new method works even better when the observing angle is relatively larger.