Annual cycle of surface solar radiative cloud forcing in the South-East Pacific stratocumulus regime: Comparison of buoy and satellite observations

Although marine stratocumulus cloud coverage is regarded as one of the most significant regulators of the radiation budget over the eastern subtropical oceans, it is poorly represented in global climate models. The Woods Hole Oceanographic Institute (WHOI)'s Ocean Reference Station (WORS) located at 20 deg S 85 deg W has collected observations of surface thermodynamic variables and broadband radiative fluxes continuously since October 2000. A technique to derive stratocumulus cloud fraction from surface downward longwave (LW) fluxes is combined with observations of downward solar radiative flux (SW) applied to the buoy observations to give a three-year climatology (for 2001-2003). Seasonal, inter-seasonal and average diurnal variations in surface solar cloud forcing and its relationship to cloud cover are obtained for the initial three years of observations. The results are compared to ISCCP products.