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  • Author or Editor: Anton C. M. Beljaars x
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Anton C. M. Beljaars and Fred C. Bosveld

Abstract

This paper describes and interprets the 1987 data from Cabauw, the Netherlands, which can be used to test land surface schemes in stand-alone mode. The data are available from the authors for model development and research. It consists of half-hour averages of forcing data (wind, temperature, specific humidity at 20-m height, downward solar and thermal radiation, and precipitation) and validation data (net radiation, sensible heat flux, latent heat flux, ground heat flux, and soil temperature). To obtain a continuous time series of the forcing parameters and the surface energy fluxes, it was necessary to use a model to fill in the missing observations. The quality of the observations and the reliability of model data are assessed by exploiting the redundancy in the observations and by comparing the model output with the data when both are available. The monthly averages of sensible heat flux are believed to be accurate to within ±5 W m−2 and the monthly means of net radiation and latent heat flux to within ±10 W m−2. An analysis of the evaporation data shows that evaporation from the interception reservoir is very common and that the canopy resistance can be modeled in terms of solar radiation, soil moisture, and atmospheric moisture deficit.

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Pedro Viterbo and Anton C. M. Beljaars

Abstract

A new version of the ECMWF land surface parameterization scheme is described. It has four prognostic layers in the soil for temperature and soil moisture, with a free drainage and a zero heat flux condition at the bottom as a boundary condition. The scheme has been extensively tested in stand-alone mode with the help of long observational time series from three different experiments with different climatological regimes: the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment in the United States, Cabauw in the Netherlands, and the Amazonian Rainforest Meteorological Experiment in Brazil. The emphasis is on seasonal timescales because it was felt that the main deficiencies in the old ECMWF land surface scheme were related to its capability of storing precipitation in spring and making it available for evaporation later in the year. It is argued that the stand-alone testing is particularly important, because it allows one to isolate problems in the land surface scheme without having to deal with complicated interactions in the full three-dimensional model.

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