Comparison of Radiation Budget at the TOA and Surface in the Antarctic from ERBE and Ground Surface Measurements

Abstract

Radiative fluxes at the top of the atmosphere (TOA) and the surface were compared at two Antarctic stations, Syowa and the South Pole, using Earth Radiation Budget Experiment (ERBE) data and surface observations. Fluxes at both sites were plotted against cloud amounts derived from surface synoptic observations. Throughout the year over the snow- and ice-covered Antarctic, cloud radiation was found to heat the surface and cool the atmosphere; cloud longwave (LW) effects were greater than cloud shortwave (SW) effects. Clouds have a negligible effect on the absorption of SW by the atmosphere in the interior, and clouds slightly increase the absorption of SW by the atmosphere along the coast. At the TOA, the LW cloud effect was heating along the coast in summer and winter, heating in the interior during summer, and slight cooling in the interior during winter. This unique TOA cloud LW cooling was due to the extremely low surface temperature in the interior during winter. At the TOA, clouds induced SW cooling in the interior and along the coast; sorting of pixel-scale ERBE data and surface cloud observations was needed to demonstrate this. The monthly averaged fluxes at the surface and TOA were compared, and the net radiative fluxes for the atmospheric column were estimated. The atmospheric column loses net radiant energy throughout the year with an asymmetrical seasonal variation. The loss of net radiant energy by the atmosphere is much larger than the loss by the surface.