A meteor radar network study on the polar-to-tropical mesospheric coupling during the 2018 Sudden Stratosphere Warming

Abstract

Using advanced meteor radar network observations along with ERA5 data, we report observational evidence of polar to tropical mesospheric teleconnections during the 2018 major sudden stratosphere warming (SSW) event in the northern hemisphere. A peak SSW on February 14, 2018, characterized by a ˜45 K rise in polar stratosphere temperature and a zonal wind reversal of ˜(-25) m/s at 60°N and 10 hPa, is observed. In the tropical lower mesosphere, a maximum zonal wind reversal (-24 m/s) compared with that identified in the extra-tropical regions was observed. Moreover, a time delay in the wind reversal between the tropical/polar stations and the mid-latitudes was detected. The wind reversal in the mesosphere is due to the propagation of dominant intra-seasonal oscillations (ISOs) of 30-60-days and the presence and superposition of 8-day period planetary waves (PWs). The ISOs phase propagation is observed from the high-to low-latitudes (60 °N to 20 °N) in contrast to 8-day PWs phase propagation, indicating the change in the meridional propagation of winds during SSW. However, the superposition of dominant ISOs and weak 8-day PWs could be responsible for the delay of the wind reversal in the tropical mesosphere. Therefore, this study has strong implications for understanding the reversed (polar to tropical) mesospheric meridional circulation during SSW.