Transport and Mixing associated with Rossby Wave Breaking in GFDL Dynamical Core

Atmospheric transport and mixing plays an important role in the global energy balance and the distribution of health-related chemical constituents. Previous studies suggest a close linkage between large-scale transport and Rossby wave breaking (RWB). In this work, we use the GFDL spectral dynamical core to investigate this relationship and study the response of RWB-related transport in different climate scenarios.

In a standard control run, we quantify the contribution of RWB to the total transport and mixing of an idealized tracer. In addition, we divide the contribution further into the two types of RWB – anticyclonic wave breaking (AWB) and cyclonic wave breaking (CWB) -- and contrast their efficiency at transport and mixing. Our results are compared to Polvani and Esler (2007) in which the transport ability of the two types of RWB is studied for individual baroclinic wave life-cycles.

In a series of sensitivity runs, we study the response of RWB-related transport and mixing to various forms of external forcing. Specifically, we investigate the influence of topography, seasonality and diabatic heating similar to the projected global warming pattern. The responses of the mean strength, frequency, and the variability of RWB-related transport are documented and the implications for the transport and mixing in a warmer climate are discussed.