The role of eddy diffusivity on a poleward jet shift

Lei Wang, Sukyoung Lee

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The authors use a quasigeostrophic (QG) two-layer model to examine how eddies modify the meridional asymmetry of a zonal jet. The initial asymmetry is introduced in the model's "radiative equilibrium state" and is intended to mimic a radiatively forced poleward jet shift simulated by climate models. The calculations show that the initial "poleward" jet shift in the two-layer model is amplified by eddy potential vorticity fluxes. This eddy-accentuation effect is greater as the baroclinicity of the equilibrium state is reduced, suggesting that seasonal variations in baroclinicity may help explain observed and modeled jet-shift sensitivity to season. The eddy-accentuated jet shift from the corresponding radiative equilibrium state is more clearly visible in the slowly varying, eddy-free reference state of Nakamura and Zhu. This reference state formally responds only to nonadvective, nonconservative processes, but ultimately arises from the advective eddy fluxes. The implication is that fast eddies are capable of driving a slowly varying jet shift, which may be balanced by nonconservative processes such as radiative heating/cooling.

Original languageEnglish (US)
Pages (from-to)4945-4958
Number of pages14
JournalJournal of the Atmospheric Sciences
Issue number12
StatePublished - 2016

All Science Journal Classification (ASJC) codes

  • Atmospheric Science


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