An estimate of the surface shortwave cloud forcing over the western Pacific during TOGA COARE

Estimates of the shortwave cloud forcing at the surface have been computed for the TOGA COARE Intensive Observation Period (IOP) using the IMET buoy surface insolation measurements. Two different methods have been employed to calculate the clear-sky surface insolation. The first is based on an empirical approximation using the buoy observations. The second incorporates both modeling and empirical procedures. The net surface shortwave cloud forcing values derived from these two methods are -103 and -107 Wm(-2), respectively. These values indicate that for the COARE IOP, the surface cooling effect from shortwave cloud forcing is comparable to that from latent heat flux (-108.5 Wm(-2)). Comparing IOP values of OLR and MSU rain rate to their climatological values indicates that the mean cloudiness during the IOP corresponds closely to climatology, suggesting that these estimates of shortwave cloud forcing may be fairly representative of the climatological value.