Saurabh,i hope the land values are automatically taken care by the ferret while making zonal/meridional/box averages. is it so?It is. Missing datapoints are regarded as non-existent. When average is computed, instead of(dx1*a1 + dx2*a2 + missing + dx4*a4) / (dx1+dx2+dx3+dx4),ferret computes(dx1*a1 + dx2*a2 + dx4*a4)/(dx1+dx2+dx4).For integral, it computesdx1*a1 + dx2*a2 + dx4*a4,ignoring the third gridpoint.Ryo