MODIS与NCEP大气可降水量资料的比较分析

Comparison of Atmospheric Precipitable Water Amounts between MODIS and NCEP

利用中国大陆地区2001年4个季节(1、4、7、10月)中8d和4m的NCEP资料,对整层大气的比湿进行积分得到大气可降水量。选用了同时同地的MODIS大气可降水量资料,然后对两者进行了对比分析。结果发现:在中国西北、内蒙地区MODIS大气可降水量资料要比NCEP资料普遍偏大,而在东南和华南部分地区则普遍偏小。如果对上述两个地区的MODIS资料分别乘以修正系数0.933983和1.07686,则两者的差别可控制在0.2cm以内。因此,MODIS大气可降水量资料经过修正后,可以为卫星反演模式提供同化性较好的输入资料。

The NCEP and MODIS data of 8 days in 4 months (January,April,July and October) of different seasons are used in this paper to estimate the atmospheric precipitable water over China.First,the precipitable water is derived from integrating the relative humidity over the whole layer atmosphere from the NCEP data.Second,we employ the model put forward by Bao-Cai Gao and Kaufman to derive the precipitable water from the MODIS data.The results show that the MODIS atmospheric precipitable water data is generally greater than the NCEP data in the northwest and inner mongolia area of China.But in the southeast and part of south area of China the MODIS atmospheric precipitable water data is small than the NCEP data.If we multiply MODIS atmospheric precipitable water data with 0.933983 and 1.07686 over previous two areas respectively,the difference between two data is less than 0.2cm.It is accurate enough to most satellite derived model.So we can conclude that after revised the MODIS atmospheric precipitable water data can be used to satellite derived model and can improve the retrieval accuracy of some satellite remoting model.