A new view of tropospheric Rossby wave breaking variability and effects

We introduce a relatively simple but efficacious method for analyzing Rossby wave breaking based on the geometry of potential vorticity (PV) contours on isentropic surfaces. The method distinguishes cyclonic from anticyclonic breaking, quantifies the spatial scale and amplitude of breaking waves, and allows association between breaking and the PV gradient both upstream and downstream from the wave breaking region.

Applying the method to reanalysis data over the Northern Hemisphere, we find conditions under which breaking over the Atlantic basin is correlated or anticorrelated with breaking over the Pacific basin at various time lags. Focusing on the location (vertical as well as horizontal), strength, and variability of the wave breaking regions, we examine the signature of breaking as seen in anomalous upper level PV and streamfunction (thus allowing association with NAO polarity) for composites of cyclonic/anticyclonic breaking events as well as for composites of reflecting/nonreflecting breaking events.