Articles | Volume 33, issue 9
Ann. Geophys., 33, 1183–1193, 2015
Ann. Geophys., 33, 1183–1193, 2015

Regular paper 30 Sep 2015

Regular paper | 30 Sep 2015

Multi-year observations of gravity wave momentum fluxes at low and middle latitudes inferred by all-sky meteor radar

V. F. Andrioli1, P. P. Batista1, B. R. Clemesha1, N. J. Schuch2, and R. A. Buriti3 V. F. Andrioli et al.
  • 1Instituto Nacional de Pesquisas Espaciais – INPE, São José dos Campos, SP, Brazil
  • 2Centro Regional Sul de Pesquisas Espaciais, Santa Maria, RS, Brazil
  • 3Universidade Federal de Campina Grande, Campina Grande, PB, Brazil

Abstract. We have applied a modified composite day analysis to the Hocking (2005) technique to study gravity wave (GW) momentum fluxes in the mesosphere and lower thermosphere (MLT). Wind measurements from almost continuous meteor radar observations during June 2004–December 2008 over São João do Cariri (Cariri; 7° S, 36° W), April 1999–November 2008 over Cachoeira Paulista (CP; 23° S, 45° W), and February 2005–December 2009 over Santa Maria (SM; 30° S, 54° W) were used to estimate the GW momentum fluxes and variances in the MLT region. Our analysis can provide monthly mean altitude profiles of vertical fluxes of horizontal momentum for short-period (less than 2–3 h) GWs. The averages for each month throughout the entire data series have shown different behavior for the momentum fluxes depending on latitude and component. The meridional component has almost the same behavior at the three sites, being positive (northward), for most part of the year. On the other hand, the zonal component shows different behavior at each location: it is positive for almost half the year at Cariri and SM but predominantly negative over CP. Annual variation in the GW momentum fluxes is present at all sites in the zonal component and also in SM at 89 km in the meridional component. The seasonal analysis has also shown a 4-month oscillation at 92.5 km over SM in the zonal component and over CP at the same altitudes but for the meridional component.

Short summary
Multi-year observations of gravity wave momentum fluxes have been analyzed at three different sites using meteor radar data. This is a first, as no such experimental results on the latitudinal dependence of these parameters at low latitudes had been derived with ground-based instruments in the MLT region before. Until now similar studies had been carried out with satellites and circulation models. Therefore this thematic can be lead to a valuable scientific contribution.