Intercomparison of conventional and new methods for estimating eddy kinetic energy  

作　　者：Wenyu Li Guidi Zhou Xuhua Cheng 

机构地区：[1]College of Oceanography,Hohai University,Nanjing 210098,China [2]Key Laboratory of Marine Hazards Forecasting of Ministry of Natural Resources,Hohai University,Nanjing 210098,China

出　　处：《Acta Oceanologica Sinica》2024年第12期1-12,共12页海洋学报(英文版)

基　　金：The National Natural Science Foundation of China under contract No.42276002;the Fund of State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanography,Chinese Academy of Sciences under contract No.LTO2201;the Fund of Key Laboratory of Marine Hazards Forecasting,Ministry of Natural Resources,China under contract No.LOMF2201。

摘　　要：We introduce a new method, the piecewise Reynolds mean(PREM), for decomposing the flow velocity into the mean-flow and eddy-flow parts in the time domain for subsequent calculation of the mean flow kinetic energy(MKE) and eddy kinetic energy(EKE). Compared with conventional methods like the Reynolds mean and running mean(RUM), PREM has the advantage of exact balance between the MKE and EKE, without the additional residual kinetic energy(RKE), while retaining time-dependent mean-flow. It is mathematically simple and computationally lightweight, depending on a pre-defined separation scale for the mean-flow and eddies. Based on satellite observations and the separation scale of 1 year, we compare PREM with RUM, as well as another newly proposed method, the eddy detection and extraction(EDEX). The latter is based on objective identification of mesoscale eddies and eddy anomaly extraction algorithms, and is therefore only suitable for mesoscale eddy energetics, but independent of separation scales. It is shown that compared with RUM, PREM gives larger mean EKE and stronger interannual variability. In strong-current and eddy-rich regions, the two methods differ the most(max: Kuroshio Extension, root-mean-sqaure-difference = 60.3 J/m^(3));but in areas with weak current and eddy, the difference accounts for the largest fraction of total EKE(max: south of the Aleutian Islands, 208%). EKE estimated by the two methods is out of phase(min correlation coefficient = 0.38). The mean EKE and standard deviation from the EDEX method resemble the PREM with 1-year separation scale, but is generally smaller in magnitude.

关 键 词：mesoscale eddy kinetic energy piecewise Reynolds mean 

分 类 号：P731.2[天文地球—海洋科学]