Surface-flux aggregation in heterogeneous terrain

Aggregation of surface fluxes in non-homogeneous terrain is a difficult task due to the highly nonlinear processes governing especially the momentum Aux. Results of the current work are high-resolution maps of land-surface momentum Bur in a strongly heterogeneous mid-latitude area in Europe. and aggregated values of the aerodynamic roughness lengths. This paper describes the development of a flux aggregation model based on a linearized set of the atmospheric flow equations solved by fast Fourier transforms. This is computationally efficient, therefore a large amount of data can be handled quickly. The input data to the model are high-resolution (30 m x 30 m) roughness maps derived from classified satellite images and assigned meteorological field values within a region (100 km x 100 km). The model deals with neutral flow only. The momentum-flux results from this objective (physically based) method compare well with other models and experimental field data.