云柱含水量 (常称为云水路径, 以下简写为L)是气象学中一个重要的物理参量。星载微波辐射计是目前监测全球范围云水路径分布和变化的最强有力的技术手段。已上天的微波辐射计 (如SSM/I)反演云水路径L的算式需要进一步改进发展;将要上天的仪器 (如日本的ADEOSⅡ AMSR)反演L的算式需要建立。采用物理 统计反演方法, 建立了一个L反演算式。主要过程是, 先根据辐射传输模式模拟得到的资料, 建立云水量L与有云无云亮温差之间的关系式;无云时的亮温由低频通道 (SSM/I的 19GHz)及通过SSM/I大量晴天的资料建立的关系式求得。算式反演结果的对比表明, 尽管作为验证的资料量极少且本身有很大的不确定性, 但总体来说, 我们算式的反演结果是可信的。

Cloud liquid water path L (i.e. vertically integrated cloud liquid water) is an important parameter in meteorology and in the study on cloud radiation interaction. It has already been demonstrated that the space borne microwave radiometer is a powerful tool for monitoring the distribution and variation of L on global scale. However, the L retrieval algorithm for on orbit SSM/I still has to be improved or renewed, and in parallel the algorithm is being developed for AMSR on board the ADEOS Ⅱ which will be launched in the near future. The aim of this work is to develop an algorithm for determining over ocean cloud L using the physico statistical method. A simple relationship is obtained between liquid water path and the difference of brightness temperatures (Δ T_B) in cloudy and clear atmospheres from the simulation data with a radiative transfer model. In the algorithm, only the relationship L Δ T_B in channel of vertically polarized 37 GHz (37 V) is used because it has smaller rms error. The T_B at 37 V in ‘clear' atmosphere is derived through a relationship with T_B at 19.35 V obtained by regression of SSM/I observation data in really clear atmospheres. The L results retrieved from SSM/I measurements by the present algorithm and two other algorithms are compared to the ISCCP L data. It is shown that the present L retrieval algorithm yields quite reliable retrievals of cloud liquid water path.