matlab_class/gcmfaces_calc/gcmfaces_section.m

function [LO,LA,FLD,X,Y]=gcmfaces_section(lons,lats,fld,varargin);
%purpose: extract a great circle section (defined by two points) from a field
%         or a latitude circle (defined by one latitude)
%
%inputs:        lons/lats are the longitude/latitude vector
%               fld is the gcmfaces field (can incl. depth/time dimensions)
%optional:      sortByLon to sort point by longitude (default = 0 -> sort by latgitude) 
%outputs:       LO/LA is the vector of grid points longitude/latitude
%               FLD is the vector/matrix of grid point values (from fld)

if nargin>3; sortByLon=varargin{1}; else; sortByLon=0; end;

global mygrid;

if length(lats)==2;
    if lats(1)==-90&lats(2)==90; 
        error('need to specify latitude range under 180'); 
    end;
  line_cur=gcmfaces_lines_transp(lons,lats,{'tmp'});
elseif length(lats)==1;
  tmp1=abs(mygrid.LATS-lats);
  tmp2=find(tmp1==min(tmp1));
  tmp2=tmp2(1);
  line_cur=mygrid.LATS_MASKS(tmp2);
else;
  error('wrong specification of lons,lats');
end;
secP=find(line_cur.mskCedge==1);
secN=length(secP);

%lon/lat vectors:
LO=zeros(secN,1); LA=zeros(secN,1); 
%sections:
n3=max(size(fld{1},3),1); n4=max(size(fld{1},4),1); FLD=zeros(secN,n3,n4);
%counter:
ii0=0; 
for ff=1:secP.nFaces;
  tmp0=secP{ff}; [tmpI,tmpJ]=ind2sub(size(mygrid.XC{ff}),tmp0);
  tmp1=mygrid.XC{ff}; for ii=1:length(tmpI); LO(ii+ii0)=tmp1(tmpI(ii),tmpJ(ii)); end;
  tmp1=mygrid.YC{ff}; for ii=1:length(tmpI); LA(ii+ii0)=tmp1(tmpI(ii),tmpJ(ii)); end;
  tmp1=fld{ff}; for ii=1:length(tmpI); FLD(ii+ii0,:,:)=squeeze(tmp1(tmpI(ii),tmpJ(ii),:,:)); end;
  ii0=ii0+length(tmpI);
end;

%sort according to increasing latitude or longitude:
if sortByLon; 
  [tmp1,ii]=sort(LO); %sort according to increasing longitude
else;
  [tmp1,ii]=sort(LA); %sort according to increasing latitude
end;
LO=LO(ii); LA=LA(ii); FLD=FLD(ii,:,:);

%output axes for ploting with pcolor
nr=length(mygrid.RC);
nx=length(LO);
X=[]; Y=[];
if size(FLD,2)==nr&sortByLon; 
    X=LO'*ones(1,nr);
    Y=ones(nx,1)*mygrid.RC';
elseif size(FLD,2)==nr&~sortByLon;
    X=LA'*ones(1,nr);
    Y=ones(nx,1)*mygrid.RC';
elseif size(FLD,1)==nr&sortByLon; 
    X=LO';
    Y=ones(nx,1);
elseif size(FLD,2)==1&~sortByLon; 
    X=LA';
    Y=ones(nx,1);
end;
    
1	gforget	1.4	function [LO,LA,FLD,X,Y]=gcmfaces_section(lons,lats,fld,varargin);
2	gforget	1.1	%purpose: extract a great circle section (defined by two points) from a field
3	gforget	1.2	% or a latitude circle (defined by one latitude)
4	gforget	1.1	%
5			%inputs: lons/lats are the longitude/latitude vector
6			% fld is the gcmfaces field (can incl. depth/time dimensions)
7	gforget	1.2	%optional: sortByLon to sort point by longitude (default = 0 -> sort by latgitude)
8	gforget	1.4	%outputs: LO/LA is the vector of grid points longitude/latitude
9			% FLD is the vector/matrix of grid point values (from fld)
10	gforget	1.1
11	gforget	1.2	if nargin>3; sortByLon=varargin{1}; else; sortByLon=0; end;
12
13	gforget	1.1	global mygrid;
14
15	gforget	1.2	if length(lats)==2;
16	gforget	1.5	if lats(1)==-90&lats(2)==90;
17			error('need to specify latitude range under 180');
18			end;
19	gforget	1.2	line_cur=gcmfaces_lines_transp(lons,lats,{'tmp'});
20			elseif length(lats)==1;
21			tmp1=abs(mygrid.LATS-lats);
22			tmp2=find(tmp1==min(tmp1));
23			tmp2=tmp2(1);
24			line_cur=mygrid.LATS_MASKS(tmp2);
25			else;
26			error('wrong specification of lons,lats');
27			end;
28			secP=find(line_cur.mskCedge==1);
29			secN=length(secP);
30	gforget	1.1
31			%lon/lat vectors:
32	gforget	1.4	LO=zeros(secN,1); LA=zeros(secN,1);
33	gforget	1.1	%sections:
34	gforget	1.4	n3=max(size(fld{1},3),1); n4=max(size(fld{1},4),1); FLD=zeros(secN,n3,n4);
35	gforget	1.1	%counter:
36			ii0=0;
37			for ff=1:secP.nFaces;
38			tmp0=secP{ff}; [tmpI,tmpJ]=ind2sub(size(mygrid.XC{ff}),tmp0);
39	gforget	1.4	tmp1=mygrid.XC{ff}; for ii=1:length(tmpI); LO(ii+ii0)=tmp1(tmpI(ii),tmpJ(ii)); end;
40			tmp1=mygrid.YC{ff}; for ii=1:length(tmpI); LA(ii+ii0)=tmp1(tmpI(ii),tmpJ(ii)); end;
41			tmp1=fld{ff}; for ii=1:length(tmpI); FLD(ii+ii0,:,:)=squeeze(tmp1(tmpI(ii),tmpJ(ii),:,:)); end;
42	gforget	1.1	ii0=ii0+length(tmpI);
43			end;
44
45	gforget	1.2	%sort according to increasing latitude or longitude:
46			if sortByLon;
47	gforget	1.4	[tmp1,ii]=sort(LO); %sort according to increasing longitude
48	gforget	1.2	else;
49	gforget	1.4	[tmp1,ii]=sort(LA); %sort according to increasing latitude
50	gforget	1.2	end;
51	gforget	1.4	LO=LO(ii); LA=LA(ii); FLD=FLD(ii,:,:);
52	gforget	1.1
53	gforget	1.4	%output axes for ploting with pcolor
54			nr=length(mygrid.RC);
55			nx=length(LO);
56			X=[]; Y=[];
57			if size(FLD,2)==nr&sortByLon;
58			X=LO'*ones(1,nr);
59			Y=ones(nx,1)*mygrid.RC';
60			elseif size(FLD,2)==nr&~sortByLon;
61			X=LA'*ones(1,nr);
62			Y=ones(nx,1)*mygrid.RC';
63			elseif size(FLD,1)==nr&sortByLon;
64			X=LO';
65			Y=ones(nx,1);
66			elseif size(FLD,2)==1&~sortByLon;
67			X=LA';
68			Y=ones(nx,1);
69			end;
70