利用星载微波辐射计AMSR-E数据反演海洋地球物理参数

Geophysical parameters retrieving algorithm of AMSR

从微波辐射传输原理出发,通过理论模拟的亮温建立了海洋和大气参数的反演算法,利用AMSR-E数据进行地球物理参数的反演验证,并利用Wentz算法进行相同参数的反演,以判断反演的效果。研究表明:在使用各种方法进行参数反演的时候,反演结果和实际值之间存在很好的相关性,但是都存在一个系统偏差需要修正。通过与NCEP和TAO浮标两组数据的比较发现,同样的算法反演结果的均方根误差不同,采用浮标数据比较的反演结果明显好于NCEP数据,原因可能是NCEP数据存在一定的不确定性。算法反演大洋海面温度和风速的均方根误差分别为0.73K和1.21m/s。

Space-borne microwave radiometer plays an important role in retrieving geophysical parameters of the global ocean surface. The Advanced Microwave Scanning Radiometer （AMSR-E）, launched on May 4, 2002 aboard NASA＇s Aqua spacecraft, is a passive microwave sensor that precisely measures microwave emission from the earth surface and atmosphere with multiple frequency bands. AMSR-E can measure a series of oceanic parameters, such as atmospheric water vapor, cloud liquid water, precipitation, sea surface wind, sea surface temperature, sea ice, snow cover, and soil moisture. In this paper, an ocean surface microwave emission/scattering algorithm and an atmospheric radiation algorithm are developed for retrieving geophysical parameters from AMSR-E brightness temperatures. Sea surface wind, sea surface temperature, water vapor, and cloud liquid water of global ocean are retrieved. The results are validated by NCEP reanalysis data, as well as TAO buoy data on the Pacific Ocean. The retrievals are also compared with those from Wentz2000 algorithms for evaluating accuracy of the algorithm. It is found that there are excellent correlations between the in situ parameters and those retrieved from either statistical algorithms or physical algorithms. It is also found that there exits system biases in all retrieved parameters which can be well corrected by a linear equation. The results compared with NCEP＇s are different from those with TAO＇s, which may results from the uncertainties in NCEP data. The final RMS error of sea surface wind, sea surface temperature are 1.21m/s, 0.73K, respectively, comparing with TAO ＇s.