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Abstract: We report the first observations of a high‐ and middle‐latitude neutral mesospheric density response to geomagnetic storms. Interhemisphere mesospheric densities are estimated using data from meteor radars at Davis Station (68.6°S, 77.9°E), Svalbard (78.3°N, 16°E) and Tromsø (69.6°N, 19.2°E), which are located under the auroral zone; the Mohe (53.5°N, 122.3°E), and Beijing (40.3°N, 116.2°E) meteor radars, located in northern midlatitudes, and the Microwave Limb Sounder (MLS) on the Aura satellite. Both case studies and a superposed epoch analysis indicate that geomagnetic storms can significantly influence mesospheric density, causing a greater than ~10% decrease in the auroral zones and a ~5% decrease at higher midlatitudes. With such large changes, it is reasonable to suspect that geomagnetic storms influence the dynamics of the high and middle latitudes mesosphere. [ABSTRACT FROM AUTHOR]

We report an analysis of the neutral mesosphere density response to geomagnetic activity from January 2016 to February 2017 over Antarctica. Neutral mesospheric densities from 85 to 95 km are derived using data from the Davis meteor radar (68.5°S, 77.9°E) and the Microwave Limb Sounder on the Aura satellite. Spectral and Morlet wavelet analyses indicate that a prominent oscillation with a periodicity of 13.5 days is observed in the mesospheric density during the declining phase of solar cycle 24 and is associated with variations in solar wind high-speed streams and recurrent geomagnetic activity. The periodic oscillation in density shows a strong anticorrelation with periodic changes in the auroral electrojet index. These results indicate that a significant decrease in neutral mesospheric density as the geomagnetic activity enhances. [ABSTRACT FROM AUTHOR]