Interpolation of global-mapped data

All —

I have a map at half-degree resolution that describes lightning frequency across the world. That is, size(data_halfDeg) = [360 720]. I want to interpolate this to quarter-degree resolution, for which I'm using the following:

[X ,Y ] = meshgrid(1:720,1:360) ;
[Xq,Yq] = meshgrid(1:0.5:720.5,1:0.5:360.5) ;
data_quarterDeg = interp2(X,Y, data_halfDeg,Xq,Yq) ;

First of all, please let me know if that looks right :-)

My main question has to do with this being data that wraps around in the X dimension—that is, the columns data_halfDeg(:,[1 720]) are right next to each other in the real world, straddling the prime meridian. This means that I should actually linearly interpolate column data_quarterDeg(:,1) as the mean of columns data_halfDeg(:,[1 720]), but I don't believe interp2() does that.

Is there a way I can force this method of interpolation? (Other than, I suppose, doing it manually.) Thanks in advance.