Diagnostic Framework Linking Eddy Flux Ellipse with Eddy-Mean Energy Exchange  

作　　者：Ru Chen Yi Yang Qianqian Geng Andrew Stewart Glenn Flierl Junyi Wang 

机构地区：[1]Tianjin Key Laboratory for Marine Environmental Research and Service,School of Marine Science and Technology,Tianjin University,Tianjin 300072,China [2]The University of California,Los Angeles,Los Angeles,CA 90025,USA [3]Massachusetts Institute of Technology,Cambridge,MA 02139,USA [4]China Oilfield Services Limited,Tianjin 065201,China

出　　处：《Ocean-Land-Atmosphere Research》2024年第1期10-25,共16页海洋-陆地-大气研究(英文)

基　　金：supported by the National Natural Science Foundation of China(grant number 42076007);the First-Class University Construction Fund.

摘　　要：The design of non-eddy-resolving numerical models requires a good understanding and an appropriate representation of the eddy-mean flow feedback.To understand this feedback,we propose a diagnostic framework that links eddy geometry with the eddy-mean energy exchange terms in the Lorenz energy diagram.This framework provides explicit mathematical formulas that link eddy-mean energy exchange rates with both the mean state structure and the properties of eddy momentum ellipses and eddy buoyancy ellipses.Considering that the mean flow contains both along-and cross-stream variations,we decompose the eddy-mean kinetic energy exchange term into 3 components:one associated with the cross-stream variation in mean flow(M_(C)),one associated with the along-stream variation in mean flow(M_(A)),and one associated with the variation in mean flow(MR).We also state the corresponding geometric formulas.The geometric interpretation of M_(C) is consistent with barotropic instability theories and the literature on eddy geometry.As for M_(A),the weakening(strengthening)of mean flow in the along-stream direction corresponds to eddy kinetic energy generation(decay)through M_(A).M_(A) and a portion of MR are related under the quasi-geostrophic assumption.From a global integral perspective,both the along-stream and cross-stream variations in the mean flow contribute considerably to eddy-mean kinetic energy exchange.At the Kuroshio Extension,both the mean state energy level and eddy energy level are key to shaping the spatial pattern of eddy-mean energy exchange.This framework offers a tool for geometrically interpreting eddy-mean energy exchange,which may offer guidance for eddy parameterizations.

关 键 词：WEAKENING exchange INTERPRETING 

分 类 号：P73[天文地球—海洋科学]