Young, G.S., and R.A. Pielke, 1983

Application of terrain height variance spectra to mesoscale modeling

J. Atmos. Sci., 40, 2555-2560

Abstract

The distribution of terrain height variance with wavelength is important for determining the required horizontal grid spacing for mesoscale models so that a subgrid-scale terrain parameterization need not be calculated. One-dimensional terrain height variance spectra for western Colorado are calculated from data collected from topographic maps and NOAA/EDIS/NGSDC 30 s average elevation data tapes. The terrain height variance of this region is found to be linearly dependent on wavelength. The Colorado terrain height variance spectra are compared with those calculated for Wales by Bretherton and for Virginia by Pielke and Kennedy. The implications for selection of horizontal grid spacing of mesoscale models in these regions are discussed.

A general conclusion is that successful mesoscale model simulations of actual geographic areas require, as a necessary (although not a sufficient) condition, that terrain variations as a function of wavelength be evaluated for the domain of interest. Such an analysis will indicate the needed grid resolution in order to resolve adequately the entire range of terrain forcing or, alternatively, provide guidance as to how subgrid-scale terrain variations can be parameterized.