Terrain classification and derived meteorological parameters for interregional transport models

Abstract A procedure is outlined to incorporate surface characteristics in air pollution models. Deposition velocity, energy exchange and surface roughness are considered, because the knowledge of these parameters is essential in more advanced transport models, which no longer use the Pasquill stability scheme. An estimate of the terrain properties is obtained by inspection of land maps. For this purpose land maps with a scale 1: 250.000 are used. On areas of 10′ × 10′ (minutes of arc) the following terrain types are distinguished: water, open field, open field with scattered trees and hedges, wood, built-up areas and roads and railways. A procedure is outlined to derive from this classification the surface heat flux, deposition velocity and surface roughness. The method for the surface roughness is compared with a procedure of Smith and Carson (1977, Boundary-Layer Met . 12, 307–330) for the determination of the surface roughness in the United Kingdom.