Rossby Wave Breaking and Isentropic Stratosphere-Troposphere Exchange in 1981–2015 in the Northern Hemisphere

To better understand the potential effects of climate change on atmospheric dynamics, this paper studies Rossby wave breaking (RWB) and isentropic stratosphere-troposphere exchange (STE) in the Northern Hemisphere between 320 K and 380 K in 1981–2015 using the Modern-Era Retrospective Analysis for Research and Application Version 2 (MERRA-2) data. The isentropic STE is estimated using Contour Advection. Our results show that anticyclonic wave breaking (AWB) events have become more frequent, especially in summer at higher isentropic surfaces, and cyclonic wave breaking (CWB) events have become less frequent at 320 K. The AWB has shifted poleward in summer. The isentropic STE is found to be strongest over the regions where RWB activities are most frequent. Both isentropic STE and RWB are shown to be strongest in summer and weakest in winter. Our results do not show any discernable trends in isentropic STE in 1981–2015.