Left-hand rule for synoptic eddy feedback on low-frequency flow

Abstract

In this study, scale interaction between synoptic eddies and low-frequency flow is investigated. The synoptic eddy feedback is a key process in sustaining the low-frequency flow. We show clear evidence using NCEP reanalysis data that there is a general underlying rule-the "left-hand rule'', governing the synoptic eddy feedback onto low-frequency flow. This rule states that eddy-vorticity fluxes are directed preferentially about 90 degrees toward their left-hand side, so that they converge into cyclonic flow and diverge from anticyclonic flow. Therefore, the eddy vorticity flux plays a positive role in reinforcing low-frequency flow. Citation: Kug, J.-S., and F.-F. Jin (2009), Left-hand rule for synoptic eddy feedback on low-frequency flow, Geophys. Res. Lett., 36, L05709, doi:10.1029/2008GL036435.