Abstract: Based on MODIS data during June to August in 2008,the atmospheric water vapor content in Northeast China was retrieved by using the two-channel and the three-channel ratio method.The results showed that the two-channel ratio method performed better for the water vapor retrieval in Northeast China,and the determination coefficient for the regression of the retrieved water vapor against the measured value was 0.81.Further more,the comparison of estimated vapor content and real ground data from the sounding stations over the woodland,cropland and grassland revealed that two-channel ratio method was better than three-channel ratio method,and woodland obtained the highest retrieval precision with the determination coefficient of 0.92.Finally,the spatial distribution characteristic of vapor content was analyzed by comparing the data retrieved from the two-channel ratio method with land-use classification data.The atmospheric water vapor content was closely correlated with land-use types when other conditions were similar.Except for dry cropland,the order of average vapor content for different types of land use was basically the same: water-body>paddy-field>woodland>grassland>unused,which was consistent with the evapo-transpiration pattern of underlying surface.

Key words: MODIS, MODIS, Two-channel ratio method, Three-channel ratio method, Atmospheric water vapor