测量云液水柱含量的一个设想

云液态水柱含量是一个重要的气象学和云雾物理参数.对于云液水柱含量测量已发展了多种技术,但由于云在时空上变化很大,目前地基、飞机以及卫星测量的全部资料,都不能满足数值天气预报、人工增雨及气候变化研究等方面的工作需要.作者提出一种测云水的新方法,即从卫星-地面的微波衰减来确定云水(斜)柱量,并研究了此方法中的测量通道选择及测量方式问题,进行了初步的误差分析研究.结果表明,此方法在现有技术条件下可行,云水的测量精度不难达到20%～30%的水平.与卫星被动微波遥感结合起来,可获得精度更高的云水全球分布资料.

A Concept for Measuring Liquid Water Path from Microwave Attenuation along Satellite-Earth Path

To measure cloud liquid water path (LWP) which is an important parameter in the cloud physics and meteorology, various techniques have been developed. However, because of the observational difficulties related to high variability of clouds in space and time, all measurement techniques cannot yield global datasets of LWP to meet the needs in numerical weather prediction, precipitation enhancement, and climate change studies. The author presents a concept to determine LWP from cloud microwave attenuation along the satellite-earth surface path. An investigation has been conducted on the optimal choice of channels and mode of observations. Analysis of errors relevant to the method has also been done. The results show that (a) in principle, the proposed method can provide LWP measurements with much higher accuracy than the available (passive) satellite remote sensing; (b) the method with dual- or triple-channel combination can simultaneously observe atmospheric precipitable water (PW), LWP, and ice water path (IWP); and (c) if combined with the available satellite remote sensing techniques, it will more efficiently yield global datasets of LWP, PW, and IWP.