Modulations of Ionospheric Solar & Lunar Migrating Tides during the 2009 Stratospheric Sudden Warming by using Global Ionosphere Specification

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Wednesday, May 29, 2019

Large‐scale meteorological disturbances like sudden stratospheric warmings (SSWs) are often of interest for the investigation of a variety of mechanisms and processes that link different regions of the Earth's atmosphere across a wide range of altitudes and latitudes.

Image of graph depicting total electron content (TEC)
Reconstruction of zonal mean local time variation of total electron content (TEC) during the January 2009 SSW. (top a) The 10 day mean TEC prior to SSW. (lower) Differences in TEC from the mean state during the SSW. Left and right (b, c) columns show the reconstructed TEC without and with the lunar M2 tide considered, respectively. The results demonstrate that inclusion of the lunar tide leads to a phase shift in the TEC enhancements/depletions, which is consistent with observations.

Earlier studies have shown large and long‐lasting anomalies caused by SSWs in the Earth's daytime ionosphere. In this study, we show that the typical semi-diurnal (12-hrs) ionospheric responses in connection with SSWs are caused by the combined effect of solar and lunar semi-diurnal migrating (or sun-synchronized) tides during the 2009 SSW. The 15 day oscillation of the semi-diurnal variations is indeed a result from the beating between solar and lunar semi-diurnal migrating tides, suggesting the importance of strong enhancements in the lunar semi-diurnal migrating tide during SSWs. These results improve our understanding of the reasons for day‐to‐day variations in the ionosphere and the role of upward propagation of solar and gravitational lunar induced tides from lower altitudes during large-scale meteorological disturbances.

Publication Name: Space Weather First HAO
Author's Name: Nick Pedatella

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