Throuh the analysis of SAMStemperature data of the Nimbu S7 satellite, a specialoscillation of the zonal mean temperatUre superimposed on the seasonal variation, whosecharacter is to oscillate synchronously in the horizontal direction and to be the standingwaves in the venical direchon, is found It is proposed that this oscillation may be acharacteristic mode the atmosphere with the zonal wavenumber m=0 and meridionalwavenumber n=0, corresponding to the eigenfuntion P
00, which is exhibited as a simplevertical motion of the atmosphere. The formation of the standing waves and the harmonicoscillation may te due to the existence of the reflective levels in the vertical direction.