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 flux. Results of the current work are high‐resolution maps of land‐surface momentum flux 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.