Surface-flux aggregation in heterogeneous terrain

Aggregation of surface fluxes in non-homogeneous terrain is a difficult tas k due to the highly nonlinear processes governing especially the momentum A ux. Results of the current work are high-resolution maps of land-surface mo mentum Bur in a strongly heterogeneous mid-latitude area in Europe. and agg regated values of the aerodynamic roughness lengths. This paper describes t he development of a flux aggregation model based on a linearized set of the atmospheric flow equations solved by fast Fourier transforms. This is comp utationally efficient, therefore a large amount of data can be handled quic kly. The input data to the model are high-resolution (30 m x 30 m) roughnes s maps derived from classified satellite images and assigned meteorological field values within a region (100 km x 100 km). The model deals with neutr al flow only. The momentum-flux results from this objective (physically bas ed) method compare well with other models and experimental field data.