Regional-scale diurnal variations of outgoing infrared radiation observed by Meteosat.

Abstract

For any given area, diurnal variation of the emitted longwave radiation reveals the response of the surface and atmosphere to the astronomical diurnal forcing. However, the diurnal rhythm can be masked locally by changes in cloud cover linked to passage of weather systems. To eliminate this weather 'noise' we construct histograms of the pixel radiance counts from the Meteosat IR window channel, for regions of dimensions 250 to 1000 km, and we study their evolution with time. We find that considerable information on the diurnal variation both of surface temperature and of cloud cover at all levels, can be obtained from short sequences (3 days) of hourly Meteosat data. -Authors