function [ueast,vnorth]=uv2uevn(alon,alat,u,v)
%[ueast,vnorth]=uv2uevn(alon,alat,u,v)
% vector field [u v] in orthogonal lat-lon grid: [alon alat]
% is projected to the East and North directions [ueast vnorth]
% NOTE: x-direction is the second index
[m n]=size(alon);
%alond=[alon(2:m,:); 2*alon(m,:)-alon(m-1,:) ];
%alatd=[alat(2:m,:);   2*alat(m,:)-alat(m-1,:) ];
alond=[alon(:,2:n) 2*alon(:,n)-alon(:,n-1) ];
alatd=[alat(:,2:n)   2*alat(:,n)-alat(:,n-1) ];
       
        angc=ang_3(alat(:),alon(:),alatd(:),alond(:));
        cc=cos(angc);ss=sin(angc);
        uap=cc.*u(:)-ss.*v(:);
        vap=ss.*u(:)+cc.*v(:);
        ueast=reshape(uap,m,n);
        vnorth=reshape(vap,m,n);
