Normal mode rossby waves as revealed by UARS/ISAMS observations

Global behavior of the 5- and 10-day waves, which are typical modes of normal mode Rossby waves, has been investigated for the region up to the mesopause with the aid of Upper Atmosphere Research Satellite Improved Stratosphere and Mesospheric Sounder observations. It is found that wave structures are easily influenced in the mesosphere by nonuniform and strong background zonal winds and an increasing damping effect with height. The vertical growth of wave amplitudes is prohibited in the mesosphere even without critical regions, and amplitudes become constant or slightly decay near the mesopause. Nevertheless, estimated variations of the wind field in the mesosphere related to the waves are consistent with results of radar observations, and Rossby normal modes may fairly contribute to total wave variance there.