Anticyclonic Rossby Wave Breaking over the North Atlantic during Boreal Summer: Climatology and Impacts

Anticyclonic Rossby wave breaking (ARWB) events are characterized by the rapid and irreversible deformation of PV contours on isentropic surfaces, manifesting themselves as tongues of high-PV stratospheric air extending from the extratropics into the tropics. Previous studies have highlighted the connection between Rossby wave breaking and the modulation of localized atmospheric phenomena such as the NAO and tropical cyclogenesis. No study, however, has focused on the evolution of the synoptic scale environment throughout the lifecycle of ARWB events over the entirety of the North Atlantic as well as the basin-wide environmental changes that occur related to development and decay of these events.

This study uses 54 years (1960-2013) of NCEP-NCAR Reanalysis data to identify and develop a comprehensive spatio-temporal climatological analysis of ARWB on the 350 K isentropic surface over the North Atlantic. This data is further utilized to investigate the synoptic environments surrounding these events from both basin-wide and high-PV streamer centroid-relative perspectives. Preliminary findings suggest that the high-PV streamers associated with ARWB events introduce dry stable air from the extratropics into the tropical environment, subsequently inhibiting convection there. Results from this study may provide aid in short to medium range forecasting of North Atlantic tropical convection, which could have applications extending into the field of tropical cyclogenesis forecasting as well.