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[1] Analysis of the MLT region winds measured by a meteor radar and the evening F region vertical plasma drift (prereversal zonal electric field -PRE) measured by digisondes over low latitude sites in Brazil, provide evidence of planetary wave (PW) scale oscillations of episodic nature simultaneously at mesospheric and F region heights. $4-day and 7-day periods are found to dominate the event analyzed. The PW scale oscillations in the PRE produces strong modulation in the equatorial spread F (ESF) irregularity processes as diagnosed by the digisondes. Considerations on the PRE development mechanism involving the E layer integrated conductivity including the effect of metallic ions and tidal winds point to the source of the PRE oscillations to be PW modulation of E region tidal winds. The PW oscillations in PRE appear to be an important source of the day-to-day variability in the ESF.

[1] This paper presents a case study of the day-to-day variability in the midlatitude upper atmospheric ion temperature (~200-400 km) with a focus on variability resulting from meteorological forcing. The data are obtained by the Millstone Hill incoherent scatter radar (42.6 N, 288.5 E) on 18-31 January 2010, in coincidence with a major sudden stratospheric warming. We elucidate oscillations in ion temperature with both tidal periods (~8 h and~12 h) and non-tidal periods (>24 h) by analyzing residuals between the observed temperatures and those expected from an empirical model. We present the spatial-temporal development of periodicities in ion temperature and discuss to what degree these periodicities might be related to the sudden stratospheric warming event. The spectral location and temporal evolution of periodicities with~9.9-12.9 h and~6.2-7.9 h suggest that they are related to the semidiurnal (12 h) and terdiurnal (8 h

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[1] We present a study of the climatology of thermospheric neutral wind (TNW) meridional and zonal components measured with the 630.0 nm nightglow Fabry-Perot interferometer at the Arecibo Observatory from 1980 to 2010. We show and discuss the solar and geomagnetic dependencies as well as the long-term trend of the TNW components and their variation over time and season. A main result of this study was the detection of a substantial seasonal and local time dependence of the response of the TNW to solar and geomagnetic activity. In addition, we found that there is a long-term trend in the thermospheric neutral wind, which can be of a larger magnitude than the variation found in the seasonal, solar cycle, and geomagnetic activity influences. A major signature of this trend over the last 30 years was an increase in the meridional northward component up to 1.4 m s À1 yr À1 before midnight local time during the summer.