Observações de frentes mesosféricas em Cachoeira Paulista (CP) (23ºS, 45ºW).

Abstract

On the following nights: (1) 14-15 September 2007 (2) 5 October 2007 (3) 10 October 2007 (4) 5 March 2008 (5) 31 March 2008 and (6) 3 September 2008; Six respective propagating prominent wave fronts which separated the sky into bright and dark regions in most cases, were observed over Cachoeira Paulista (23°S, 45°W) using an all-sky airglow imager (ASI). Images of OH, Na, O2 (0,1) and OI557.7 nm airglow emissions were collected during the nights of observation. At the same place, Meteor radar was used to estimate the horizontal wind. A lidar instrument deployed at São José dos Campos (23°S, 46°W) was also used simultaneously to record temperature data of atmospheric background (mesosphere and lower thermosphere). From the adequate information gotten from the ASI, meteor radar and the lidar instrument, we could to classify the observed wave fronts into four mesospheric bore events and one wall event. This is the first simultaneous observation of a mesospheric front in Brazil using the All-sky imager, Meteor radar and Na lidar instrument. The analysis using the square of vertical wavenumber profile revealed the duct regions and the primary cause of them (Doppler or Thermal). The bore fronts observed were undular and non-undular with dark fronts in some airglow emission layers and bright fronts in others. The bore events observed were in agreement with the complimentary effect and atmospheric duct position effect on the emission layers proposed in the literature.