Study of the Quasi-5-Day Wave in the MLT Region by a Meteor Radar Chain

An extensive analysis of quasi 5-day waves (5DWs) in the mesosphere and lower thermosphere and their responses to a major sudden stratospheric warming (SSW) event (January 2013) are presented. The analysis is based on data conducted from a meteor radar chain in the period from December 2008 to November 2017 and Aura Microwave Limb Sounder satellite. The radar chain includes three stations 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, 114.6 degrees E). The 5DWs present clear interannual and seasonal variations, which are observed by both the radar wind data and Aura-temperature data. Interestingly, the ter-annual oscillation is found to be as important as the commonly recognized annual oscillation and semiannual oscillation at the three stations in both neutral wind components. The 5DWs are strong mainly during the August/September in the meridional component, while they are primarily enhanced in the period of January, April/May, and late summer in the zonal component. An enhancement of 5DWs is observed during the 2013 SSW event in the mesosphere and lower thermosphere region at the three stations. The amplitudes during the SSW are more than 2 times larger than the January average. The strength of the amplification is most prominent at MH and reduces as latitude decreases. According to the results obtained from the radar wind and Aura temperature, the enhanced 5DW modes are W1 at MH, and W2 at BJ and WH. Our results indicate that the amplification of the 5DWs is very likely associated with the 2013 SSW.