DIVGEOM Geometric decomposition of eddy vorticity flux divergence. [F1,F2,F3,F4]=DIVGEOM(DX,DY,K,L,THETA) returns the geometric decomposition of eddy vorticity flux divergence associated with variance ellipses having kinetic energy K, anisotropy L, and orientation THETA. K, L, and THETA are matrices of the same size. These are defined on an X-Y grid with x oriented in *columns* and y oriented in *rows*. DX and DY are the sampling intervals in the X and Y directions, respectively. Note that K and L are related to ellipse parameters KAPPA and LAMBDA used elsewhere in JLAB by K=KAPPA^2 and L=LAMBDA*KAPPA^2. F1, F2, F3, and F4 are four different contributions to the eddy vorticity flux divergence, as follows: F1 Quadratic variations in the linear energy L F2 Product of linear variations in THETA and L F3 Quadratic variations in the orientation THETA F4 Product of linear variations in orientation THETA For details, see Waterman and Lilly (2015), Geometric decomposition of eddy-mean flow feedbacks in barotropic systems, J. Phys. Oceanogr. [F1,F2,F3,F4,F]=DIVGEOM(...) also returns the total eddy flux divergence F, calculated directly, with F1+F2+F3+F4 = F apart from numerical error. By default, DIVGEOM calculates derivates with repeated applications of a first central difference. DIVGEOM(...,'arakawa') alternately uses a modified first central difference appropriate for models that employ an Awakawa advection scheme. __________________________________________________________________ Usage: [f1,f2,f3,f4]=divgeom(dx,dy,K,L,theta); __________________________________________________________________ This is part of JLAB --- type 'help jlab' for more information (C) 2013--2015 J.M. Lilly --- type 'help jlab_license' for details