How do I plot a colored disk on a globe?

I would like to plot a diskoid on the surface of a globe. The diskoid would colored to represent distance from the center.

ie green in the center fading to blue fading red at the edge and red everywhere outside the diskoid.

I would like to be able to both choose the radius on the diskoid and where the center point of the diskoid lies on the surface of the globe.

Here is what I have so far...not sure if I am on the right track or not.

baseLat = 53; baseLon = -60; %This is where i would like the diskoid centered

figure
axesm('globe','galt',0)
axesm ('globe','Grid', 'on');
camposm(baseLat,baseLon,1)

disk=zeros(180,360);
for i=1:180
    for ii = 1:360
        if (ii-300)^2+(i-143)^2>15^2
            disk(i,ii)=20;
        end
    end
end
meshm(disk, [1 90 0])
load coast
plotm(lat, long)
axis off
set(gcf,'Color',[0 0 0]);
set(gca,'CameraViewAngle',70)

The diskoid is really distorted and if it goes over the north pole then all bets are completely off.

Thanks