Global Relationships among the Earth's Radiation Budget, Cloudiness, Volcanic Aerosols, and Surface Temperature

Abstract

The analyses of Cess are extended to consider global relationships among the earth's radiation budget (including solar insulation and changes in optically active gass), cloudiness, solar constant, volcanic aerosols, and surface temperature. Interannual variability and correlations between Nimbus-7 THIR/TOMS cloud amount, ERB WFOV longwave, shortwaye, and net radiation, and SAM II aerosol optical depths, along with Hansen and Lebedeff's surface temperature analyses, are assessed. Solar luminosity is apparently related to the global surface temperature in the 1979?1990 time period based on the Nimbus-7 observations and an extended Hansen and Lebedeff temperature dataset. The 0.40°C range in observed global temperatures may be partitioned into a 0.15°C component due to a 2 W m?2 change in the solar constant and a 0.22°C component due to the increasing concentration of CO2 and other greenhouse gases. A relatively large component of the variance in the global temperature, cloudiness, and radiation budget signals is due to interannual earth system variability over time periods much shorter than a solar cycle (e.g., 2?4 years), for which the solar luminosity experiences no comparable fluctuation. The Nimbus-7 observations indicate that the global, annual cloud amount varies by +0.3% to ?0.5% with a pronounced quasi-biennial periodicity and is inversely proportional to the outgoing longwave flux and surface temperature. The time dependence of aerosols injected into the stratosphere by the explosive 1982 eruption of El Chichón is found to be important, along with the global cloud amount, in describing the time dependence of the earth's albedo during the period. The sign of the relationship between the earth's surface temperature and the net radiation is of fundamental importance. The Nimbus-7 ERB net radiation observations compared to surface temperature analyses imply a stable climate (at least about some set point that is dictated by other conditions such as the concentration of C02 and other greenhouse gases, that do not apply over the relatively short time interval considered here). When considering future mission we conclude that reliable and well-characterized satellite datasets with of ideally one to two decades or more are required to perform quantitative analyses of the relationships among different elements of the earth's climate system. To accomplish this, the instruments? calibration should be maintained and valid to a stability that permits the analysis of interannual global fluctuations at the 0.2% level.