Skip to Main content Skip to Navigation
New interface
Journal articles

Effect of Latitudinal variations in low-level baroclinicity on eddy life cycles and upper-tropospheric wave-breaking processes.

Abstract : An analysis of the potential vorticity gradient and the refractive index in quasigeostrophic (QG) flows on the sphere reveals that the absolute vorticity and the stretching parts have two contradictory effects on the horizontal shape of the baroclinic waves when the full variations of the Coriolis parameter are taken into account in each term. The absolute vorticity effect favors the anticyclonic (southwest–northeast) tilt and anticyclonic wave breaking (AWB) and is stronger in the upper troposphere. In contrast, the stretching effect promotes the cyclonic (northwest–southeast) tilt and cyclonic wave breaking (CWB) and is more efficient at lower levels. A positive eddy feedback acting on the latitudinal variations of the zonal winds is deduced. Because the absolute vorticity and the stretching effects are respectively more and less efficient with increasing latitude, a more northward (southward) jet renders AWB more (less) probable and CWB less (more) probable; the jet is pushed or maintained more northward (southward) by the eddy feedback. Idealized numerical experiments using two aquaplanet models on the sphere, a three-level QG model, and a 10-level primitive equation (PE) model, confirm our analysis. Two strategies are employed: first, a normalmode approach for jets centered at different latitudes; second, an analysis of long-term integrations of the models where the temperature is relaxed toward zonally as well as nonzonally uniform restorationtemperature profiles located at different latitudes. The positive eddy feedback is much less visible in the QG model and CWB is very rare because it does not contain the stretching effect (because of the constant Coriolis parameter in the stretching term).
Complete list of metadata
Contributor : Bruno Dal Cin Connect in order to contact the contributor
Submitted on : Monday, November 29, 2021 - 3:57:38 PM
Last modification on : Thursday, November 17, 2022 - 4:11:19 AM


[15200469 - Journal of the Atm...
Publisher files allowed on an open archive


Distributed under a Creative Commons Attribution 4.0 International License




Gwendal Riviere. Effect of Latitudinal variations in low-level baroclinicity on eddy life cycles and upper-tropospheric wave-breaking processes.. Journal of the Atmospheric Sciences, 2009, 66 (6), pp.PP. 1569-1592. ⟨10.1175/2008JAS2919.1⟩. ⟨meteo-00424457⟩



Record views


Files downloads