Accession Number : ADA117409

Title :   The Roughness Lengths Associated with Regions of Heterogeneous Vegetation and Elevation.

Descriptive Note : Final rept. 1 Oct 80-31 Mar 81,


Personal Author(s) : MacArthur,Charles D ; Haines,Patrick A

PDF Url : ADA117409

Report Date : May 1982

Pagination or Media Count : 41

Abstract : Algorithms for calculating seasonal roughness lengths from digitized descriptions of surface vegetation and man-made objects are described. The 'monthly characteristic vegetation roughness' for a one square kilometer plat is a log average of 100 roughness lengths, which correspond to the vegetation codes. Seasonal histograms for each square kilometer were also computed. The concept of a roughness length due to changes in elevation is used to derive an algorithm for its calculation. Both algorithms were used to compute roughness lengths for two regions of Central Europe. Region A contained 12,000 square kilometers of elevation and vegetation data at 100 meter intervals. Both types of roughness length were calculated for this region. Region B contained nearly 400,000 square kilometers of elevation data at a 63.5 meter interval. Region B includes region A. In region B only roughness lengths due to elevation change were calculated. The calculated vegetation and elevation roughness lengths in region A were compared. The elevation roughness lengths are generally greater than those due to vegetation in hilly country. The elevation roughness lengths of region A and region B were also compared. It is concluded that the elevation roughness algorithms are sensitive to the horizontal interval between data points.

Descriptors :   *Terrain models, *Vegetation, *Mapping, Surface roughness, Elevation, Topographic maps, Boundary layer, Algorithms, Digital maps, Histograms, Central Europe

Subject Categories : Cartography and Aerial Photography

Distribution Statement : APPROVED FOR PUBLIC RELEASE