Examples of the Meteorological Capability of the High Resolution Infrared Radiometer on the Nimbus I Satellite

Abstract

The High Resolution Infrared Radiometer (HRIR) carried by the Nimbus I meteorological Satellite provided detailed nighttime cloud information in the vertical as well as in the horizontal dimension. When the instantaneous field of view of the HRIR is completely filled by either a cloud or the earth's surface through clear skies, the temperature of the radiating surface can be inferred. Cloud top heights can, therefore, be deduced by relating the equivalent blackbody temperature from the satellite to the temperature-height profile of the atmosphere, providing the temperature decreases monotonically with height. Equivalent blackbody temperatures average 5K colder than air shelter temperatures based on 40 stations reporting clear skies. Cloud patterns over water are well defined from daytime HRIR data, but over land some clouds tend to be indistinguishable from land when the sum of the thermal emission and the reflected solar radiation from the cloud equals that from the land. The capability of both the photofacsimile displays and the computer maps to depict synoptic information demonstrates that HRIR data from future meteorological satellites should provide a new operational tool.