Barotropic Effects on Atmospheric Storm Tracks

Abstract

The effect of barotropic dynamics on atmospheric midlatitude storm tracks is investigated for the Northern Hemisphere winter season, using both observed data analyses and linear barotropic model experiments. It is shown that when the model flow is initialized with a realistic wave packet, barotropic processes alone can produce key features of the observed storm track structure. The author attributes this result both to the barotropic waveguide effect and to the fact that the geographical locations of barotropic growth coincide reasonably well with the baroclinic growth of the atmospheric storm track eddies. This study also shows that barotropic dynamics are more relevant for storm tracks in lower latitudes than for those in higher latitudes, consistent with the fact that the lower-latitude storm tracks are more closely associated with the subtropical jet, rather than with the polar front jet that is driven by baroclinic eddies.