A procedure is presented for mapping regularly spaced grid indices int
o smoothly varying grid-cell-top heights. The total vertical domain is
split into three regions of arbitrary vertical extent: a bottom regio
n of uniform-size grid cells; a top region of uniform-size cells (but
different than the bottom); and a middle transition region where cell
sire varies smoothly between the top and bottom sizes. Four parameters
specify the complete distribution of grid-cell tops.