Energetics Analysis of the Global Circulation during the Special Observation Periods of FGGE

Abstract

A global energetics analysis is presented for the FGGE SOP-1 and SOP-2 with ECMWF and GFDL data sets. Both global integral properties and spectral characteristics are examined. There is a large discrepancy between the present FGGE analysis and previously available estimates concerning the level of available potential energy and kinetic energy. This discrepancy is attributable to an earlier restriction of data coverage. There is a significant seasonal difference in the energy reservoir of the Northern Hemisphere, whereas the difference is minor in the Southern Hemisphere. This leads to a seasonal contrast of the globally integrated energy budget which comes mostly from the Northern Hemisphere. Both the global energy level and the intensity of the general circulation are more pronounced during SOP-1 than during SOP-2. One major focus of attention in this study is an energetics comparison of ECMWF and GFDL data sets. There is a twofold difference in the intensity of the general circulation as measured with these two data sets. The energetics diagnosis indicates that the operational modes of the general circulation as described by these two data sets also differ considerably. The contrasts between SOP-1 and SOP-2 and between the ECMWF and GFDL versions of the data sets are apparent in the pattern of energy flow in the wavenumber domain.