Some Characteristic Differences in the Earth's Radiation Budget over Land and Ocean Derived from the Nimbus-7 ERB Experiment

Abstract

Broad spectral band Nimbus-7 Earth Radiation Budget (ERB) experiment data are analyzed for top-of-the-atmosphere regional variations in near-ultraviolet visible and near-infrared reflected solar radiation. Regional differences in the noon vs midnight outgoing longwave flux are also studied, as is the difference in land and ocean net radiation budgets. Temporal sampling problems are discussed. The annual behavior is examined for a year (June 1979 through May 1980) on a global scale and for five selected study areas, and reasonable agreement is found with the results of previous investigators. The studies show a marked difference in behavior between oceanic and continental regions. The annual global total, near-ultraviolet visible and near-infrared albedo values obtained were, respectively, 30.2, 34.6 and 25.9. However, over the continents, the near-IR albedo was often the largest, but clouds and snow sharply decrease the near-IR albedo over land. Over the oceans, the average noon and midnight outgoing longwave-flux density is nearly identical but with regional and seasonal differences of several watts per square meter. Over the continents, the noon-emitted flux density averages were 15?25 W m?2 larger than the midnight value but with large regional and seasonal variations. The annually averaged global net radiation derived from the ERB scanner is ?23.8 W m?2 for the land areas, +6.5 W m?2 for ocean areas and ?3.2 W m?2 total.