Waterbody Identification in Cloud- contaminated NOAA/AVHRR Image
应用气象卫星识别薄云覆盖下的水体

AVHRR data from Meteorological Satellites have potential in flood moni-toring due to the high time resolution and low cost.Unfortunately,AVHRR,whichis a kind of visible-infrared sensor,cannot detect land surface through cloud,andcloud- free image is quite rare during flood period due to the bad weather,so cloudcontamination is one of the main obstacles in flood monitoring using AVHRR data. Based on the spectral characteristics of groundcovers and the principle of satelliteobservation,this paper puts forward a simple but effective method for water iden-tification using AVHRR data, which is the ratio band of channel 2 by channel 1. By using this method,waterbody can be identified not only in cloud- free areas, butalso under semitransparent cloud and in cloud shadow.This method was used suc-cessfully in the 1 991 flood disaster in Huaihe river basin.