A multispectral study of the St. Louis area under snow-covered conditions using NOAA-7 AVHRR data

Abstract

Albedos and equivalent blackbody temperatures from the 5-channel Advanced Very High Resolution Radiometer (AVHRR) on board the NOAA-7 satellite have been examined for two consecutive passes of the satellite over the St. Louis area when snow was on the ground. The albedo difference for channel 1 (visible) between St. Louis and a typical rural area was − 16%, much larger than urban-rural albedo differences found in previous studies under snow-free conditions. The albedo difference between channel 1 and channel 2 (near-infrared) appears to be a better indicator of the snow boundary than either channel alone. The channel 4 (11 μm) equivalent blackbody temperature difference between the warmest part of St. Louis and a typical rural area was 3 K during the day and 2.5 K at night, about the same as urban-rural temperature differences found under snow-free conditions. Day-night temperature differences were nearly the same in urban as in rural areas. Largest day-night differences were found in forested portions of the snow-covered area. Slightly larger (about 0.5 K) day-night differences were observed in the commercial-industrial area of St. Louis than in the residential area. This may be caused by residential heating. Finally, hot industrial targets were easily observed in 3.7 μm images. These targets may be useful for accurate registration of AVHRR images.