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CR 29:53-61 (2005)  -  doi:10.3354/cr029053

Estimation of areal precipitation for runoff modelling using wind data: a case study in Sweden

Barbro Johansson1,*, Deliang Chen2,3

1Swedish Meteorological and Hydrological Institute, 601 76 Norrköping, Sweden
2Earth Sciences Centre, Göteborg University, Box 460, 405 30 Göteborg, Sweden
3Laboratory for Climate Studies/National Climate Center, China Meteorological Administration, 100081 Beijing, China

ABSTRACT: In mountainous regions, rainfall distribution is influenced by topography in combination with wind speed and direction. This has implications for estimates of catchment precipitation as input to hydrological models. The objective of this work was to investigate if wind information can be used to improve the accuracy of precipitation estimates, particularly for operational applications. A geostrophic wind, computed from pressure observations, was assumed to represent the airflow at an altitude relevant for precipitation distribution. Interpolated values of precipitation (optimal interpolation) were verified directly against point observations. In some mountainous catchments with low annual evapotranspiration, estimates of long-term mean areal precipitation could be verified through the water balance equation. The effects of the interpolations with and without wind information on the performance of a rainfall-runoff model were also investigated. There were 2 main factors in favour of using wind information in the interpolation: (1) a better description of the seasonal distribution; and (2) a lower sensitivity to reductions in the number of meteorological stations.

KEY WORDS: Areal precipitation · Orographic enhancement · Interpolation · Rainfall-runoff modelling · Spatial distribution · Airflow · Sweden

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