“…The alternative approach, adopted by Ryssel et at. [45] is to multiply the vertical distribution by a Gaussian (for reasons that are not readily apparent). When Monte-Carlo simulation techniques are applied to a grid with depth resolution element A, eg (3.14) becomes G(x ,y,z) =^^F (x,y-nA, z-i•mA) , (3.15) n,m where the indices n and m are chosen to fill the area A.…”