Global mean long-wave cloud radiative forcing derived from HIRS2/MSU

Using a physical approach, global ten-day mean long-wave cloud radiative forcing has been derived from satellite data for a period from January 1979 to May 1981. This forcing shows small (2 to 3 W/sq m) variations for diurnal, seasonal, and interannual time scales, even though the detailed structure of cloud fields may have considerable temporal and spatial variability. The amplitude of variations of the hemispheric mean is much larger than the global mean; the largest variation is over land areas (20 W/sq m) of the Southern Hemisphere, and the smallest variation is over the ocean (6 W/wq m) of the Northern Hemisphere.