Interhemispheric Meridional Circulation During Sudden Stratospheric Warming

Although sudden stratospheric warming (SSW) is mainly a northern high-latitude phenomena, there are several reports of a concomitant global dynamical response throughout the mesosphere and lower thermosphere. Published reports based on model simulations so far attributed such variabilities to changes in global circulation; however, there is no clear explanation of how all these regions are physically connected during SSW events. The present investigation uses wind observations from two ground-based specular meteor radars over northern high latitudes and midlatitudes and global winds from a high-altitude meteorological analysis system to characterize global mesospheric circulation anomalies for major SSW events during 2010 and 2013. During these events radar observations and the reanalysis winds exhibited strong southward winds over the two northern midlatitude and high-latitude stations. By removing seasonal variability from the high-altitude meteorological analyses, we show that these southward wind anomalies are indeed part of a larger global-scale circulation, which gets set up during SSW and extend from the Northern pole to low-latitude regions of Southern Hemisphere in the mesosphere and lower thermosphere altitudes. These results also offer a possible explanation of how low-latitude ionospheric electrodynamics are influenced by the changes in the circulation set in during SSW at high latitudes.