In order to have the color scale be consistent between the two, the axes CLim property must be the same for the two plots. In particular you would want min() of all of the data combined, to max() of all of the data combined as your axes CLim for both axes. You can use the clim convenience function or set the axes CLim property to establish the bounds. Having done that, it is not necessary that the color bars show the same range. You can record the handles of the colorbar() objects, and you can set the Limits property of the colorbar object. The Limits property determines the portion of the color axes that is drawn in the colorbar, but does not affect the color scaling of the graphics objects.
combined_data = [delta_2_top(:); delta_3_top(:)];
minten = min(combined_data);
maxten = max(combined_data);
pcolor(X, Y, delta_2_top);
cb1.Limits = [min(delta_2_top), max(delta_2_top)];
pcolor(X, Y, delta_3_top);
cb2.Limits = [min(delta_3_top), max(delta_3_top)];
The green 0 point would occur roughly 2/3 of the way through for the first plot, and would occur at the right side for the second plot.
