Long-term changes in the thermospheric neutral winds over Arecibo: Climatology based on over three decades of Fabry-Perot observations

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(-1) yr(-1) before midnight local time during the summer.