从SSM/I亮温反演海洋上大气可降水量

Retrievals of Over Ocean Precipitable Water from the SSM/I Measurements with Several Regression Algorithms

利用日本ＮＡＳＤＡ提供的ＳＳＭ／Ｉ和相应的海岛气象探空资料，对几种有代表性的ＳＳＭ／Ｉ反演大气可降水量算式的反演结果进行了比较分析。结果表明，目前业务反演采用的算式过高地估计了低大气可降水量，而对于高大气可降水量（＞４．５ｇ／ｃｍ２）又过低地估计了；对反演值进行一个三次多项式订正，从总体上并不改善反演效果。针对以上问题。

A SSM/I and collocated radiosonde observation data set provided by the NASDA (Japan) was used to retrieve the total precipitable water (PW) over oceans. The retrieval results obtained with several regression algorithms were compared to the radiosonde measurements. It is shown that : (a) the routinely operational algorithm of Alishouse et al. (1990) yields significant underestimates in high PW regime and overestimates in low PW regime; (b) a cubic correction by Colton and Poe (1994) is not sufficient and globally improves very slightly the retrieval results; and (c) the regression algorithm with the form of brightness temperature (TB) function ln(280-TB) seems to give a little largely scattered retrievals but without noticeable over and underestimates in low and high PW regimes. To improve the estimation of the oceanic precipitable water from the SSM/I TB measurements, a composite algorithm with different forms of TB function in low, medium and high PW regimes is proposed and tested.