Thermospheric Wind Longitudinal Variations in the Southern Mid Latitudes

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Abstract
Recent thermospheric wind observation by a balloon borne instrument HIWIND over New Zealand in April 2025 combined with ground based Fabry Perot interferometer observations in Brazil provides a good opportunity to examine the longitudinal variations in the southern mid latitude region. The results showed noticeable longitudinal variations, which could be generated by nonmigrating tides propagating from the lower atmosphere. HIWIND also provided the first southern hemisphere daytime thermospheric wind observations. Combined HIWIND data with COSMIC 2 radio occultation observations of ionosphere profiles in the southern hemisphere we will examine the interaction between the ionosphere and thermosphere. Using the first principle model TIEGCM we simulated the southern hemisphere thermospheric winds and ionosphere profiles to compare with the HIWIND and COSMIC observations. HIWIND results help to reveal significant discrepancy between observations and simulations and point toward the direction for future improvement of the simulations.