ANALYSIS ON THE SOURCE AND SINK OF KINETIC ENERGY OF ATMOSPHERIC 30—60 DAY PERIOD OSCILLATION AND THE PROBABLE CAUSES

Based on ECMWF daily grid point data in summer (May—August),1981,the distributionfeatures of the source and sink of kinetic energy of atmosphere 30—60 day oscillation,including itshorizontal distribution characteristics and its vertical structure characteristics,are investigatedsystematically with diagnostic analysis methods over a latitude belt between 80°N and 60°S.Also,theprobable reasons for the existence of the source and sink of low frequency kinetic energy (LFKE) arediscussed preliminarily.Results show that the horizontal distribution of the sources and sinks ofkinetic energy of atmospheric 30—60 day oscillation is extremely different.The significant sourcesand sinks of LFKE mainly exist in the oceans and the coastal regions of continents or islands in themid-high latitudes.It is also found that,in the vertical direction,the sources and sinks of kineticenergy of 30—60 day oscillation display barotropic structure in the mid-high latitudes of bothhemispheres,but dispaly baroclinic structure in the equtorial region,and in the horizontal direction,the sources and sinks mainly display zonal wave-like distribution.The source and sink of LFKE aredeterminded by ageostrophic wind effect,frictional effect,interaction between sub-grid-scalesystems,nonlinear interaction,and the flux-divergence of LFKE transported by transient wind.There are some regional reasons for the generation of sources and sinks which are not completelyidentical in different areas.