Upper Atmosphere Wind Pattern During St. Patrick's Day Geomagnetic Storm: Fabry-Perot Interferometer Measurements and Modeling

St. Patrick's Day storm was the strongest geomagnetic storm of Solar Cycle 24. This event caused strong disturbances in the upper atmosphere wind pattern. We study the neutral wind disturbances using both the observations and modeling. The neutral wind observations were made with the Fabry-Perot interferometer at the Geophysical Observatory (51.7N, 103.1E) of the Institute of Solar-Terrestrial Physics. The instrument was designed to determine the spectral characteristics of optical airglow at middle latitudes. The model calculations were performed with the Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere (GSM TIP) developed in the WD IZMIRAN. The model gives the spatial-temporal structure of the main thermospheric characteristics (temperature, composition, neutral wind velocity, and density). All model equations are solved by the finite difference method. We compare thermospheric wind velocities at different heights obtained from the observation and model simulation and analyze both common features and differences. Of greatest interest are changes in thermospheric wind during the main phase of the geomagnetic storm when heating of the neutral gas in auroral zone increases significantly due to auroral electron precipitation and Joule heating. Possible mechanisms for the storm-time neutral wind formation revealed from the modeling are discussed.