Hg. Mayr et al., EQUATORIAL OSCILLATIONS MAINTAINED BY GRAVITY-WAVES AS DESCRIBED WITHTHE DOPPLER SPREAD PARAMETERIZATION - II - HEURISTIC ANALYSIS, Journal of atmospheric and solar-terrestrial physics, 60(2), 1998, pp. 201-213
The Doppler Spread Parameterization (DSP) for gravity waves (GW) devel
oped by Hines is applied to the zonal momentum budget at the equator.
For sufficiently large oscillation amplitudes in the background zonal
winds, comparable to the GW induced wind variability, the momentum sou
rce is intermittent and as such it represents a nonlinearity of third
or generally odd order. This kind of nonlinearity generates, besides h
igher harmonics, the fundamental harmonic itself which is retained in
a simplified analytical solution that can describe self-sustained osci
llations without invoking external, time dependent forcing. The formul
ation is discussed to provide some understanding of the numerical resu
lts presented in the companion paper. (C) 1998 Elsevier Science Ltd.