Atmospheric wind effects on the gravity wave propagation observed at 22.7° S-Brazil

Abstract

An all-sky CCD imager for the airglow OH, O 2 and OI (557,7 nm) measurements was operated at Cachoeira Paulista (22.7°S, 45.0°W) from September 1998 to August 1999. Dominant gravity wave events were extracted and studied. It is found that the horizontal wavelengths are typically from 5 to 60 km and the period from 5 to 35 minutes with the horizontal phase speed of 1 to 80 m/s. A ray tracing technique was applied in order to find out the gravity wave sources and to investigate the propagation of these waves through the atmosphere. The CIRA-86 reference zonal wind and temperature models and the GSWM-02 tidal wind model were used as the background condition in the present analysis. The tidal wind strongly affects the gravity wave propagation and miss-leads the location of the wave source. The major part of the tropospheric sources of the gravity waves is located 400 km around the observation site, and these sources were related with the lightning activity that is associated with strong tropospheric convection.