Study of the Quasi 10-Day Waves in the MLT Region During the 2018 February SSW by a Meteor Radar Chain

We present a study of the quasi 10-day waves (Q10DWs) in the mesosphere and lower thermosphere (MLT) during a sudden stratospheric warming (SSW) event in February 2018 based on three meteor radars located at Mohe (MH, 53.5 degrees N, 122.3 degrees E), Beijing (BJ, 40.3 degrees N, 116.2 degrees E), and Wuhan (WH, 30.5 degrees N, 116.6 degrees E). The enhanced Q10DWs are observed in the meridional component at MH and in the zonal component at BJ and WH. In the meridional component, the monthly mean Q10DW amplitudes in February 2018 are greater than 10 m/s at MH but weaker than similar to 7 m/s at BJ and WH. In the zonal component, monthly mean Q10DWs amplitudes are similar to 15 m/s at BJ and WH but only 9 m/s at MH. These latitudinal differences of the Q10DWs in the MLT region are very likely due to the Q10DW activity in the lower atmosphere and the mean background winds. The strong southward winds might bring the wave energy to MH in the meridional component during the occurrence of SSW, while the enhanced Q10DWs in the zonal component at BJ and WH are likely associated with the strong Q10DWs in the lower atmosphere and weakening eastward winds after the central date of the SSW. The significance test indicates that the enhanced Q10DWs in the meridional wind of MH and in the zonal wind of WH are very likely affected by the SSW. In addition, nonlinear interactions between the Q10DWs and other planetary waves also modulate the variations in the MLT region at BJ during the SSW.