Cloud height determination by satellite stereography.

Abstract

A feasibility study of deriving cloud height was conducted by the use of two geosynchronous meteorological satellites (GMS-1 and GMS-2). The GMS-1 was located at about 140°E on the equator and the GMS-2 was at about 160°E on the equator. The cloud height was observed by the GMS-1 through the visible and IR channels at 23:32 GMT on Sept. 17, '81 (23:36 GMT for the GMS-2), but at equator the time difference between the data acquisitions by these two satellites is less than a minute due to their spin rate and attitude difference. These observations were made by the Meteorological Satellite Center, JMA. To obtain the good quality of anaglyphic photographs, apparent image distortions were reduced through the mapping process by which all the pixels in the observational coordinates were converted to those in the longitude-latitude coordinates. Upon deriving the cloud height, the earth was assumed to be spheroid. It was found from the analysis that it is possible to obtain the fine structure of cloud in a relative accuracy of 200 m, but a large number of dependable reference points around the target cloud are required as well as the precise orbit parameters, to obtain a high accuracy of absolute cloud height. This analysis was practically impossible by the use of infrared technique due to the unknown emissivity of cloud and the vertical temperature profiles.