matlab_class/gcmfaces_calc/calc_overturn.m

function [FLD]=calc_overturn(fldU,fldV);
%object:    compute meridional overturning streamfunction
%inputs:    fldU and fldV are the fields of grid point transport
%output:    FLD is the streamfunction
%
%notes:     mygrid.LATS_MASKS is the set of quasi longitudinal lines along which
%               transports will integrated, as computed in gcmfaces_lines_zonal

global mygrid;

%initialize output:
n3=max(size(fldU.f1,3),1); n4=max(size(fldV.f1,4),1);
FLD=NaN*squeeze(zeros(length(mygrid.LATS_MASKS),n3+1,n4));

%prepare fldU/fldV:
fldU(isnan(fldU))=0; fldV(isnan(fldV))=0;

dxg=mk3D(mygrid.DXG,fldU); dyg=mk3D(mygrid.DYG,fldU); drf=mk3D(mygrid.DRF,fldU);
for k4=1:n4;
fldU(:,:,:,k4)=fldU(:,:,:,k4).*dyg.*drf.*mygrid.hFacW*1e-6;
fldV(:,:,:,k4)=fldV(:,:,:,k4).*dxg.*drf.*mygrid.hFacS*1e-6;
end;

%use array format to speed up computation below:
fldU=convert2array(fldU); fldV=convert2array(fldV);
n1=size(fldU,1); n2=size(fldU,2);
fldU=reshape(fldU,n1*n2,n3*n4); fldV=reshape(fldV,n1*n2,n3*n4); 

for iy=1:length(mygrid.LATS_MASKS); 

   %get list ofpoints that form a zonal band:
   mmu=convert2array(mygrid.LATS_MASKS(iy).mmu);
   nnu=find(~isnan(mmu)); mmu=mmu(nnu)*ones(1,n3*n4);
   mmv=convert2array(mygrid.LATS_MASKS(iy).mmv);
   nnv=find(~isnan(mmv)); mmv=mmv(nnv)*ones(1,n3*n4);

   %do the area weighed average along this band:
   tmpu=sum(fldU(nnu,:).*mmu,1);
   tmpv=sum(fldV(nnv,:).*mmv,1);

   %store:
   FLD(iy,1:n3,:)=-flipdim(cumsum(flipdim(reshape(tmpu+tmpv,n3,n4),1),1),1);

end; 

FLD(:,end,:)=0;


1	gforget	1.3	function [FLD]=calc_overturn(fldU,fldV);
2	gforget	1.2	%object: compute meridional overturning streamfunction
3			%inputs: fldU and fldV are the fields of grid point transport
4			%output: FLD is the streamfunction
5	gforget	1.3	%
6			%notes: mygrid.LATS_MASKS is the set of quasi longitudinal lines along which
7			% transports will integrated, as computed in gcmfaces_lines_zonal
8	gforget	1.1
9			global mygrid;
10
11			%initialize output:
12			n3=max(size(fldU.f1,3),1); n4=max(size(fldV.f1,4),1);
13	gforget	1.3	FLD=NaN*squeeze(zeros(length(mygrid.LATS_MASKS),n3+1,n4));
14	gforget	1.1
15			%prepare fldU/fldV:
16			fldU(isnan(fldU))=0; fldV(isnan(fldV))=0;
17
18			dxg=mk3D(mygrid.DXG,fldU); dyg=mk3D(mygrid.DYG,fldU); drf=mk3D(mygrid.DRF,fldU);
19			for k4=1:n4;
20			fldU(:,:,:,k4)=fldU(:,:,:,k4).dyg.drf.mygrid.hFacW1e-6;
21			fldV(:,:,:,k4)=fldV(:,:,:,k4).dxg.drf.mygrid.hFacS1e-6;
22			end;
23
24			%use array format to speed up computation below:
25			fldU=convert2array(fldU); fldV=convert2array(fldV);
26			n1=size(fldU,1); n2=size(fldU,2);
27			fldU=reshape(fldU,n1n2,n3n4); fldV=reshape(fldV,n1n2,n3n4);
28
29	gforget	1.3	for iy=1:length(mygrid.LATS_MASKS);
30	gforget	1.1
31			%get list ofpoints that form a zonal band:
32	gforget	1.3	mmu=convert2array(mygrid.LATS_MASKS(iy).mmu);
33	gforget	1.1	nnu=find(~isnan(mmu)); mmu=mmu(nnu)ones(1,n3n4);
34	gforget	1.3	mmv=convert2array(mygrid.LATS_MASKS(iy).mmv);
35	gforget	1.1	nnv=find(~isnan(mmv)); mmv=mmv(nnv)ones(1,n3n4);
36
37			%do the area weighed average along this band:
38			tmpu=sum(fldU(nnu,:).*mmu,1);
39			tmpv=sum(fldV(nnv,:).*mmv,1);
40
41			%store:
42			FLD(iy,1:n3,:)=-flipdim(cumsum(flipdim(reshape(tmpu+tmpv,n3,n4),1),1),1);
43
44			end;
45
46			FLD(:,end,:)=0;
47
48