Satellite-based estimates of longwave radiation for agricultural applications

Geostationary satellites provide information that enables frequent, routine and cost-effective estimates of both downwelling longwave radiation and incident solar radiation for use by agricultural and other applications, at a resolution that cannot be practically matched by ground-based measurements. We develop a new parameterization for downwelling longwave radiation at the earth's surface that incorporates a simple and accurate method for estimating clear-air downwelling longwave radiation at the surface, a real-time cloud product coated from Geostationary Operational Environmental Satellite (GOES) data, plus a modicum of hourly surface synoptic data, This parameterization is tested against pyrgeometer data gathered in Wisconsin in 1998 and produces a RMS accuracy of 20 Wm(-2) for half-hourly average downwelling longwave radiation and less than 5 Wm(-2) for 24 h averages. (C) 2000 Elsevier Science B.V. All rights reserved.