Using incoherent scatter radar to investigate the neutral wind long-term trend over Arecibo

Abstract

[1] Thermospheric neutral winds can be the most important driver when modeling ionospheric densities and temperatures. Several papers in this special edition show interesting features of the neutral winds behavior during the last 30 years at the Arecibo Observatory (18.3°N, 66.75°W; ∼28.25° dip latitude) using Fabry-Perot Interferometer (FPI) data. A neutral wind vector that changes its direction, becoming more dominantly eastward over the years and a meridional neutral wind component that decreases in magnitude, were found. The main goal of this work is to look for similar evidence of long-term trends in the radar derived winds that might support these recent discoveries and explore the associated ionospheric parameter measurements to look for the effects of these changing winds on the ionosphere. With this purpose in mind, Incoherent Scatter Radar (ISR) measurements of the F region vector drifts are used to derive the corresponding meridional thermospheric neutral wind along the magnetic field over Arecibo during 20 years. Major findings include a decreasing long-term trend (lowering) of the height where the F2- layer peak density occurs (hmF2), which could be related with a more increased downward flux of the ionosphere. A slight decrease in the peak density of the F2- layer (NmF2) after local midnight also was found during the period studied. The meridional wind along the magnetic field derived from ISR data also revealed a long-term trend, becoming more northward during the period studied, with a maximum variation between 02:30UT and 05:30UT.