Open AccessA Baroclinic Laminar State for Rotating Stratified Flows
Author(s) -
Chenglin Sun
Publication year - 2008
Publication title -
journal of the atmospheric sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.853
H-Index - 173
eISSN - 1520-0469
pISSN - 0022-4928
DOI - 10.1175/2008jas2693.1
Subject(s) - baroclinity , laminar flow , barotropic fluid , froude number , physics , turbulence , mechanics , stratification (seeds) , stratified flow , vortex , classical mechanics , stratified flows , scalar (mathematics) , nonlinear system , geology , geometry , flow (mathematics) , mathematics , seed dormancy , germination , botany , quantum mechanics , dormancy , biology
A baroclinic laminar model is developed as the late-time equilibrium state in the free decay of rotating stratified turbulence under low-Froude-number scaling. Vertical motions are suppressed by stratification and ambient rotation, and in the laminar end state the flow assumes a quasi-two-dimensional form. Geometric analyses of this nonlinear conservative model reveal an f-plane baroclinic topology characterized by vertical alignment, vanishing nonlinearity, and the complete absence of helicity. Equivalent-barotropic flow is the only nonunique baroclinic solution, and its horizontal topology is restricted to a unidirectional jet and a circular vortex. Such a depleted geometry results from the constraint of basic equations where density is advected as an active scalar. It provides a baroclinic mechanism for the formation of coherent structures in geophysical flows.