The accuracy of downward short- and long-wave radiation at the earth's surface calculated using simple models

• Published in: Meteorological applications Vol. 11; no. 1; pp. 33 - 39
• Main Authors: Finch, J. W., Best, M. J.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.03.2004; John Wiley & Sons, Ltd
• ISSN: 1350-4827; 1469-8080
• DOI: 10.1017/S1350482703001154

Estimates of the downward global solar and long-wave radiations are commonly made using simple models. We have tested the estimates produced by a number of these simple models against the values predicted by the radiative transfer model used in a climate model in order to determine their suitability for global applications. For clear sky, two simple models were comparable, but under cloudy conditions a combination of a clear-sky model based on the Angstrom-Prescott equation (which deals with the downwelling solar radiation) with a cloud transmissivity utilising total cloud fraction proved best. The lowest root mean square errors were 27 W m−2 for clear-sky global solar radiation and 90 W m−2 for cloudy conditions. For downward long-wave radiation in clear-sky conditions, the model of Garratt (1992) performed best with a root mean square error of 24 W m−2. However, in cloudy conditions the model of Idso & Jackson (1969) performed best with a root mean square error of 22 W m−2, and, as it performs nearly as well as that of Garratt (1992) in clear-sky conditions, it is probably the best choice.