Baroclinic energy conversion as driver for Rossby wave breaking

Abstract

The topic of extreme weather in the mid-latitudes remains a subject of discussion. The response of Rossby waves (and the jetstream that tracks them) to a warming climate is very uncertain, while this large scale flow is known to be the driver for synoptic weather. A comprehensive theory on Rossby wave growth and breaking is hard to determine due to its nonlinear nature. This study advocates for the use of vertical velocity relative to isentropic surfaces to describe the conversion of available potential energy into kinetic energy. It is found that large areas of baroclinic energy conversion (BEC) can be found in the mid-latitudes in the middle as well as the upper troposphere. Intense regions of (BEC) can be found along the meridional moving jetstream in the vicinity of relative vorticity minima and maxima, meaning this could play an important role in amplifying Rossby waves. In an Eulerian frame it is found that regions of BEC coincide with jetstreaks. Results from the Lagrangian framework suggest that BEC might be the energy source of the formation or strengthening of jetstreaks.