Long- and short-period oscillations in the lunar semidiurnal tidal amplitudes in the ionosphere derived from the total electron content were investigated over Brazil from 2011 to 2014. The results showed  annual, semiannual and triannual oscillations as the dominant components. Additionally, the most pronounced short-period oscillations were observed between 7 and 11 d, which suggest a possible coupling of the lunar tide and planetary waves.

In this study, we report the climatology of migrating and non-migrating tides in mesopause winds estimated using multiyear observations from three meteor radars in the southern equatorial region. The results reveal that the climatological patterns of tidal amplitudes by meteor radars is similar to the Climatological Tidal Model of the Thermosphere (CTMT) results and the differences are mainly due to the effect of the stratospheric sudden warming (SSW) event.

Solar atmospheric tides are natural oscillations of 24, 12, 8... hours that contribute to the circulation of the atmosphere from low to high altitudes. The Sun heats the atmosphere periodically because, mainly, water vapor and ozone absorb solar radiation between the ground and 50 km height during the day. Tides propagate upward and they can be observed in, for example, the wind field. This work presents diurnal tides observed by meteor radars which measure wind between 80 and 100 km height.

In this paper, an extensive study has been done in order to investigate periodic oscillations in the start times of equatorial plasma bubbles observed over Brazil. Using OI6300 airglow images and ionograms, it was possible to detect semimonthly oscillations in the start times of equatorial plasma bubbles (EPBs) and equatorial Spread-F. This semimonthly oscillation is likely related to the lunar tide, which represents an important mechanism acting in the day-to-day variability of EPBs.

For the first time, the climatology of intermediate descending layers (~150 km) over Brazilian equatorial and low-latitude regions during the extreme solar minimum period of 2009 was investigated. The results are interesting and innovative. For this analysis we used data of height and top frequency of intermediate layers collected from a digisonde located at São Luis and Cachoreira Paulista.

This study concerns postmidnight ionospheric irregularities observed during low solar activity conditions. We analyze data from digisondes and optical imaging systems located in an equatorial region over Brazil. The results show that they occur under unfavorable and unexpected conditions. This work can be useful for space weather forecasting during low solar activity.

Equatorial ionospheric irregularities have a significant detrimental impact on a variety of space application systems in navigation and communication areas that utilize satellites, especially the Global Navigation Satellite Systems (GNSS) network. The development of these irregularities in the nighttime ionosphere is controlled primarily by ionospheric electric fields and instabilities. The effect of magnetic disturbance on these electric fields and on the irregularities is investigated here.

We present new results on the behavior of sporadic E layers (Es layers) using GPS (global positioning system) radio occultation (RO) measurements obtained from the FORMOSAT-3/COSMIC satellites and digisonde data over Cachoeira Paulista, a low-latitude station in Brazil.

This work presents four events of mesosphere fronts observed on King George Island, Antarctic Peninsula, in the year 2011. The atmospheric background environment was analyzed to investigate the propagation conditions for all cases. To investigate the sources for such cases, satellite images were used. In two cases, we found that strong tropospheric instabilities were potential sources, and in the other two cases, it was not possible to associate them with tropospheric sources.

This paper analyzes the influence of the recent deep and prolonged solar minimum on the daytime zonal and vertical plasma drift velocities during quiet time over Jicamarca, Peru. Our results show that an anomalously low zonal wind was mainly responsible for the observed anomalous behavior in the zonal drift followed by a decrease in the E-region conductivity and the dynamo electric field during 2008.

A comparative study of the quasi-16-day wave in the middle from three Brazilian stations, indicates multiple modes of the concerned wave component. The wave amplitude shows maxima in summer and winter. A potential coupling of the concerned wave with other short period planetary waves is found. The dominant wave components vary from the westward to eastward from the tropical to mid-latitude in the stratosphere. The prevailing westerly wind may favor the wave filtering of westward waves.

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.