Abstract:
This study presents comparison of low-latitude dynamical responses to boreal 2008/09 and austral 2002
winter Major Stratospheric Warming (MSW) events, as both events are of vortex split type. During these
winters, planetary wave (PW) variability and changes in low-latitude circulation are examined using
European Center for Medium Range Weather Forecasting (ECMWF) reanalysis (ERA)-interim data sets
and mesospheric wind data acquired by the MF radars at Tirunelveli (8.7°N) and Rarotonga (22°S).
Eliassen-Palm diagnostic is used to provide an evidence for the lateral PW energy propagation from high
to low-latitudes during both the MSW events. The PW flux reaches much lower latitudes during the
boreal event than during the austral event. The low-latitude westward winds at stratospheric heights are
stronger (weaker) during the boreal (austral) MSW. Weak (strong) PW wave activity at low latitude
mesospheric heights during boreal (austral) MSW indicates the influence of low-latitude stratospheric
westward winds on the vertical propagation of PW to low-latitude mesosphere.
