Time Variations of the Snow Area Detection using AVHRR/NOAA

Abstract

Applicability of a scheme developed by the authors for snow covered area detection based on satellite data is studied with a series of AVHRR/ NOAA data in snowmelt season. N-LAND database and Ground Truth Data produced from AMeDAS data are combined in the region of the Echigo Mountains, 16, 000 km². Variation of a set of detection parameters in the scheme in confirmed on two deimentional plot of ALBEDO chl, infrared ch3 or thermal infra-red ch4 of six scenes from Junuary to April in 1989. High and low clouds can also be detected by using ch4 and ch3 infra-red, respectively. The results show the threshold values increase as the solar altitude becomes high with season. Snow covered area, free-snow and cloud can be detected precisely by the scheme.