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contributor authorBakas, Nikolaos A.
contributor authorConstantinou, Navid C.
contributor authorIoannou, Petros J.
date accessioned2019-10-05T06:50:45Z
date available2019-10-05T06:50:45Z
date copyright10/31/2018 12:00:00 AM
date issued2018
identifier otherJAS-D-18-0148.1.pdf
identifier urihttp://yetl.yabesh.ir/yetl1/handle/yetl/4263603
description abstractAbstractZonal jets in a barotropic setup emerge out of homogeneous turbulence through a flow-forming instability of the homogeneous turbulent state (zonostrophic instability), which occurs as the turbulence intensity increases. This has been demonstrated using the statistical state dynamics (SSD) framework with a closure at second order. Furthermore, it was shown that for small supercriticality the flow-forming instability follows Ginzburg?Landau (G?L) dynamics. Here, the SSD framework is used to study the equilibration of this flow-forming instability for small supercriticality. First, we compare the predictions of the weakly nonlinear G?L dynamics to the fully nonlinear SSD dynamics closed at second order for a wide range of parameters. A new branch of jet equilibria is revealed that is not contiguously connected with the G?L branch. This new branch at weak supercriticalities involves jets with larger amplitude compared to the ones of the G?L branch. Furthermore, this new branch continues even for subcritical values with respect to the linear flow-forming instability. Thus, a new nonlinear flow-forming instability out of homogeneous turbulence is revealed. Second, we investigate how both the linear flow-forming instability and the novel nonlinear flow-forming instability are equilibrated. We identify the physical processes underlying the jet equilibration as well as the types of eddies that contribute in each process. Third, we propose a modification of the diffusion coefficient of the G?L dynamics that is able to capture the evolution of weak jets at scales other than the marginal scale (side-band instabilities) for the linear flow-forming instability.
publisherAmerican Meteorological Society
titleStatistical State Dynamics of Weak Jets in Barotropic Beta-Plane Turbulence
typeJournal Paper
journal volume76
journal issue3
journal titleJournal of the Atmospheric Sciences
identifier doi10.1175/JAS-D-18-0148.1
journal fristpage919
journal lastpage945
treeJournal of the Atmospheric Sciences:;2018:;volume 076:;issue 003
contenttypeFulltext


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