The Dependencies of Annular Variations in the Nighttime Thermospheric Neutral Winds

We utilize the neutral wind data from eight ground-based Fabry-Perot interferometers operated within the past decade to perform a harmonic analysis of the nighttime thermospheric winds and investigate the relative strengths of the annual, semiannual, and terannual components. The instruments are installed in three different geographic sectors, allowing a comparison of magnitude and phase in the harmonic components versus both latitude and longitude. Understanding the major variations in the neutral winds will aid in the validation of both physics-based and empirically-fit upper atmospheric models. Some comparisons of FPI wind data to HWM14 in the various regions will be given as an example.