course-idma2016/matlab/idma_area_mean.m

function [mn]=idma_area_mean(fld,msk);
% IDMA_AREA_MEAN computes area-weighted average of a
%    field (fld; 2D or 3D) over a region defined by 
%    a 0/1 mask (msk). Both fld and msk are of 
%    the gcmfaces class. If fld has a third dimension
%    (e.g., for depth or time) then mn is a vector
%
% Example: box_l=[-180 -140]; box_L=[-10 10]-30;
%          msk=(mygrid.XC>=box_l(1)&mygrid.XC<box_l(2)&...
%               mygrid.YC>=box_L(1)&mygrid.YC<box_L(2));
%
%          fileName='release1/nctiles_climatology/THETA/THETA'; 
%          fldName='THETA';
%          fld=read_nctiles(fileName,fldName,1);
%          fld=fld.*mygrid.mskC;
%
%          [mn]=idma_area_mean(fld,msk);
%          figureL; plot(mn,mygrid.RC);

gcmfaces_global;

n=size(fld{1},3);
mn=NaN*zeros(1,n);

racmsk=msk.*mygrid.RAC;
racmsk=repmat(racmsk,[1 1 n]);
racmsk(isnan(fld))=0;

for k=1:n;
    mn(k)=nansum(racmsk(:,:,k).*fld(:,:,k))/nansum(racmsk(:,:,k));
end;


1	function [mn]=idma_area_mean(fld,msk);
2	% IDMA_AREA_MEAN computes area-weighted average of a
3	% field (fld; 2D or 3D) over a region defined by
4	% a 0/1 mask (msk). Both fld and msk are of
5	% the gcmfaces class. If fld has a third dimension
6	% (e.g., for depth or time) then mn is a vector
7	%
8	% Example: box_l=[-180 -140]; box_L=[-10 10]-30;
9	% msk=(mygrid.XC>=box_l(1)&mygrid.XC<box_l(2)&...
10	% mygrid.YC>=box_L(1)&mygrid.YC<box_L(2));
11	%
12	% fileName='release1/nctiles_climatology/THETA/THETA';
13	% fldName='THETA';
14	% fld=read_nctiles(fileName,fldName,1);
15	% fld=fld.*mygrid.mskC;
16	%
17	% [mn]=idma_area_mean(fld,msk);
18	% figureL; plot(mn,mygrid.RC);
19
20	gcmfaces_global;
21
22	n=size(fld{1},3);
23	mn=NaN*zeros(1,n);
24
25	racmsk=msk.*mygrid.RAC;
26	racmsk=repmat(racmsk,[1 1 n]);
27	racmsk(isnan(fld))=0;
28
29	for k=1:n;
30	mn(k)=nansum(racmsk(:,:,k).*fld(:,:,k))/nansum(racmsk(:,:,k));
31	end;
32
33