function [ur,vr]=uvrot(u,v,rot);
% function [ur,vr]=uvrot(u,v,rot);
% rotate velocities
% by angel rot in deg
% M.Visbeck
rot=-rot*pi/180;
cr=cos(rot);
sr=sin(rot);
ur=u.*cr-v.*sr;
vr=u.*sr+v.*cr;
return