Igo Paulino

Plasma bubble zonal drift characteristics observed by airglow images over Brazilian tropical region

Using airglow images observed at Sao Joao do Cariri (7.4oS, 36.5oW; dip angle: -11oS) from September 2000 to April 2007, plasma bubblezonal drifts for ninety-seven geomagnetically quiet nights (Dst index higher than -30 nT) were calculated. The plasma bubble eastward averaged drifts presented an increase from 18:00 to 22:00 local time (LT), and followed by a deceleration. The plasma bubbles observed during high solar activity were faster after 22:00 LT. Eastward drifts observed during the summer, after 21:00 LT, were higher than drifts observed during the equinox months. Few nights had plasma bubble eastward drifts higher than 100 m/s and almost all bubbles disappeared after 02:00 LT. Averaged zonal drifts observed between -9.5 and -5.5oS were almost constant, primarily,around 23:00 LT.

Lunar tides in total electron content over Brazil

Using data from Global Navigation Satellite Systems dual frequency receivers, the lunar tides were studied in the ionospheric Total Electron Content (TEC) over Brazil from 2011 to 2014. In order to calculate the amplitudes and phases of the lunar tides, quiet magnetic days within a 27-day (window) has been used to remove the solar rotation effects. Relative residuals TEC were calculated by performing a spectral analysis by removing the solar tide contributions. Lastly, a lunar month size window was used to calculate the amplitude and phase of the lunar components. Lunar diurnal tide amplitudes showed a semiannual variation with maximum in the equinox months for almost all latitudes, while, lunar semidiurnal amplitudes were larger in December and January and may be related to sudden stratospheric warming events. Both components did not display significant longitudinal variation what could be due to the short range of longitude (30 degrees). Lunar diurnal amplitudes were basically uniform over Brazil, while lunar semidiurnal amplitudes showed some peaks over the equatorial ionization anomaly crest and minimum values near the magnetic equator.