Quasi 10‐ and 16‐Day Wave Activities Observed Through Meteor Radar and MST Radar During Stratospheric Final Warming in 2015 Spring

Abstract

AbstractBy combining observations from three meteor radars and a mesosphere‐stratosphere‐troposphere radar arranged along the 120°E meridian with reanalysis data from 20 February to 20 May 2015, we study the stratospheric final warming (SFW) in 2015 spring and planetary wave activities from the troposphere to the mesosphere and lower thermosphere (MLT) at different latitudes. There are two successive warming events with the polar mean temperature rises of 24 and 9 K at 10‐hPa level. By means of the two warming events separated by only several days, the mean temperature increases by nearly 20 K, and the mean zonal wind decreases from more than 30 m/s to about −10 m/s; thus, seasonal transition of the polar circulation is completed. The investigation shows that the quasi 10‐ (Q10DW) and 16− (Q16DW)day waves occur around the SFW. In the troposphere, their amplitudes are close to 10 m/s in the wind field. At 10‐hPa level of the stratosphere, the strong wave activities arise before the SFW, while in the MLT, the waves are amplified following the SFW with the amplitude peaks about 10 days after the SFW onset. The wave amplitude in the MLT tends to increase in the zonal wind but decrease in the meridional wind with decreasing latitude, which is roughly consistent with the Hough modes. Hence, the Q10DW and Q16DW in the MLT are distinct from those in the stratosphere, and they are likely to be generated and strengthened in situ in the upper stratosphere and MLT.