Spatial Dependence of the Relationship between Rainfall and Outgoing Longwave Radiation in the Tropical Atlantic

Abstract

We develop a Spatially dependent formula to estimate rainfall from satellite-derived outgoing longwave radiation (OLR) data and the height of the base of the trade-wind inversion. This formula has been constructed by comparing rainfall records from twelve islands in the tropical Atlantic with 11 years of OLR data. Zonal asymmetries due to the differing cloud types in the eastern and western Atlantic and the presence of Saharan sand in the cast are included. The climatological winter and summer rainfall derived from the above formula concurs with ship observations described by Dorman and Bourke. However, during the spring and fall, OLR-derived rainfall is higher than observations by 2?4 mm day?1 in the intertropical convergence zone. The largest discrepancy occurs during the fall in the region west of 28°W. Interannual anomalies of rainfall computed using this technique are large enough to cause potentially important changes in ocean surface salinity.