function pp=pred_rhi(rho,z,t)

ae=6378.1e03;
r=sqrt(rho.^2+z.^2);

thetae=t+atan((r.*cos(t))./(ae+r.*sin(t)));

rhoproj=cos(thetae);
kproj=sin(thetae);
pp(:,1)=rhoproj;
pp(:,2)=kproj;

return
end