Earth Radiation Budget Variability and the Relationship to Changes in the General Circulation
The geographical variability of the radiation balance forces the different atmospheric circulations. To fully comprehend the variability in these atmospheric flow patterns we must address the fundamental problems of how changes in the earth radiation budget (ERB) affects these circulations, and also the role of clouds in modification of the ERB. The Nimbus-7 satellite ERB climatology from 1978 -1987 is presented as well as the interannual variability. The areas with highest variations are reported for each of the ERB parameters and show the pronounced effect of the 1982-1983 El Nino. Concurrent with the ERB observations is a independent five year cloud climatology allowing for comparisons of ERB with estimates of total and multi-level cloud amounts. The area of greatest variability in the net balance occurs off the west African coast where there are mainly in convective cloudiness. Convective clouds have less net balance variation due to the reciprocity in their shortwave and longwave fluxes. The circulation data includes eight years of ECMWF global winds and temperatures from which the eddy and zonal components of the available potential and kinetic energies are computed. The circulation differences between the continental Northern Hemisphere and oceanic Southern Hemisphere are interpreted in terms of the magnitudes of these energetic terms. For the direct study of ERB and energetic comparisons, a simultaneous time series of mid-latitude ERB gradients and hemispheric averaged energetics are examined. By doing a time correlation study we found the annual cycles of the radiation gradients to lead the energetics by 2-3 weeks. The spatial relationship of the variability in the ERB related to tropical circulations is investigated through spatial correlations. Reference areas are defined from the areas of highest variability and correlated with all other global areas. Tropical ERB anomalies are also correlated with mid-latitude 500 mb geopotential anomalies derived from the ECMWF global weather data. While correlations are smaller than the ERB-ERB comparisons, the mid-latitude geopotential heights in the Gulf of Alaska are shown to have a strong connection with equatorial OLR anomalies.
- Pub Date:
- January 1990
- ATMOSPHERIC ENERGETICS;
- Physics: Atmospheric Science; Remote Sensing