how to area weight a regular grid?

I wish to weight my interpolated regular gridded data (132 x 120) so that;

data * (area of each grid box) / sum(all grid boxes)

I have tried myself using 'areaquad' and 'repmat' but the values at the end of the above equation are far too low!

I'm hoping someone knows a different / better technique.

thanks, Michael

thanks, Michael

[Michael]

anyone have any ideas?