pcolor plot on a geoid

Hi

How can I plot my pcolor in a geoid? When I plotting I just get a white map with no data.

figure(4) 
[c,h]=contour(latr,lonr,z,'linewidth',1,'color','k');
clabel(c,h); 
pcolor(lonr,latr,ug500);
shading interp
colorbar;
hold on
worldmap([20 80],[180 170])
load geoid
load coastlines
geoshow(coastlat,coastlon)
hold on
title('Den geostrofiske vind, ug ved 500 hPa')
xlabel('longitude'), ylabel('latitude')