The lunar tides in the mesosphere and lower thermosphere over Brazilian sector

Meteor radar observations at São João do Cariri (7.4°S; 36.5°W), Cachoeira Paulista (22.7°S; 45°W) and Santa Maria (29.7°S; 53.7°W) have permitted estimates to be made of winds in the mesosphere and lower thermosphere (MLT) over the Brazilian sector simultaneously. Using horizontal winds the semidiurnal lunar tide is determined from January 2005 to December 2008 for these three sites. The lunar tide is observed to reach amplitudes as large as 8 m/s. In general, the amplitude increases with height and the phase decreases with height, corresponding to an upwardly-propagating tide. The estimated vertical wavelengths are variable for some month, like December at Cachoeira Paulista for northward wind, April and June at Santa Maria for eastward wind, which indicates possible mode coupling and reflection. Characteristics similar to those seen in the Northern Hemisphere have been observed in June and October at São João do Cariri, in December at Cachoeira Paulista, in March at Santa Maria and in August at all observation sites, which suggest the presence of antisymmetric modes. Different behavior has been observed in the amplitudes, phases and vertical wavelengths at each station, indicating latitudinal variation even from the low to the equatorial region.