Equatorial dynamics observed by rocket, radar and satellite during the CADRE/MALTED campaign, 2: Mean and wave structures, coherence, and variability

Abstract

We present an analysis of the wind and temperature measurements made by rocket, radar, and satellite instrumentation in the equatorial and subtropical middle atmosphere accompanying the MALTED/CADRE campaign conducted at Alcantara, Brazil during August 1994. Measured mean winds and temperatures extended from similar to 10 to 110 km, exhibited general consistency between instruments, and revealed an oscillatory nature of the mean zonal wind with altitude at equatorial latitudes. MF radar measurements of tidal structures showed these to exhibit variability on similar to 8- and 16-day periods, but to be largely uncorrelated in time. Two-day wave structures displayed the same periodicities, but were well correlated among sites at northern and equatorial latitudes. Rocket and radar measurements at smaller scales of motion revealed inertia-gravity waves having significant temporal coherence, quadrature correlations between components indicating clear directions of propagation, and momentum flux and mean wind correlations indicative of gravity wave filtering processes. Rochet estimates of diurnal tidal amplitudes suggest that the diurnal tide achieves convectively unstable amplitudes in the upper equatorial mesosphere.