olumn thickness (essentially the ocean depth) at every 
% grid point we defined above: 

wct = tmd_interp('Gr1kmTM_v1.nc','wct',Lat,Lon); 

figure
pcolor(lon,lat,wct)
shading interp 
cb = colorbar; 
ylabel(cb,'water column thickness (m)')
cmocean deep % optional colormap 

%%
% Above, the water column thickness is zero wherever there's land. Perhaps
% you'd prefer to set the land grid cells to NaN rather than zero. Here's
% how: Just interpolate the ocean mask, set the non-ocean pixels to NaN,
% and plot ag