GLOBAL CLIMATOLOGIES OF SOLAR-RADIATION BUDGETS AT THE SURFACE AND IN THE ATMOSPHERE FROM 5 YEARS OF ERBE DATA

As a result of recent satellite-based observation programs, knowledge of the radiation budget at the top of the atmosphere has improved substantially. In comparison, there has been little improvement in knowledge of the radiation budgets at the surface and in the atmosphere. Based on a simple parameterization, global climatologies of the solar radiation budget at the surface and in the atmosphere are developed from 5 years of Earth Radiation Budget Experiment data and European Centre for Medium Range Weather Forecasts humidity data. Both data sets have global coverage on 2.5-degrees x 2.5-degrees grids. Global distributions of the solar radiation budget at the surface give maximum seasonal values of the net solar radiation for the subtropical oceans of more than 300 W m -2. The maximum seasonal absorption in the atmosphere is about 120 W m-2. Shortwave cloud forcing at the surface and in the atmosphere is also derived. Clouds reduce the seasonally averaged surface net solar radiation by up to 175 W m -2, whereas they increase seasonal net solar radiation in the atmosphere by less than 15 W m-2 . The globally and annually averaged net solar radiation budgets in the atmosphere and at surface are 83 and 157 W m - 2, respectively. Expressed as percentages of the solar radiation incident at the top of the atmosphere, these values correspond to a globally and annually averaged absorption in the atmosphere and at the surface of 24.3% and 46.0%, respectively, and a planetary albedo of 29.7%.