Volume 3 (2007) Pages 9-12
In this study, the global circulation represented by JRA-25 is examined from the viewpoint of global energetics, compared with ERA-40 and NCEP/NCAR reanalysis. Although the peak and slope of the spectrum for JRA-25 are consistent with those of the other datasets, the magnitude of energy or energy conversion is generally ERA-40 > JRA-25 > NCEP. For short waves, a rapid decrease of amplitude with increasing wave number is shown for NCEP/NCAR reanalysis and ERA-40. The energy conversion from zonal available potential energy to zonal kinetic energy, caused by zonal-mean meridional circulation, is the largest for JRA-25, which is the result of a large amount of cancellation of the local conversion term in the Hadley cell.