Mesospheric and thermospheric observations of the January 2010 stratospheric warming event

Abstract

We use two ground based Fabry–Perot interferometers (FPI) at Boulder (40°N, 105°W), Resolute (75°N, 95°W), and a meteor radar at Bear Island (75°N, 19°E) to examine the mesospheric and thermospheric winds during a sudden stratospheric warming (SSW) event in January 2010. The two high latitude wind instruments allow us, for the first time, to infer the zonal wavenumber of the semidiurnal tide on a daily basis during an SSW event. The ground based FPIs recorded enhanced lower thermosphere semidiurnal tide before and during the SSW. The two high latitude stations did not show much westward propagating semidiurnal tide with zonal wavenumber one (SW1) as predicted by model simulations. Several indications of westward propagating zonal wavenumber three semidiurnal tide (SW3) require further verification. In addition, the TIMED TIDI lower thermospheric winds at 95km also appear to show sign of SW3. High latitude terdiurnal and quaddiurnal oscillations were observed. Enhancements in the mid-latitude thermospheric semidiurnal and terdiurnal tides during the SSW were observed, which may be related to the gravity wave filtering by solar tides in the stratosphere and mesosphere. Unusually large thermospheric winds were observed before the SSW at Boulder, its connection to the planetary wave activity related to the SSW is still to be determined.