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Research article2003Peer reviewedOpen access

Boreal forest surface parameterization in the ECMWF model - 1D test with NOPEX long-term data

Gustafsson D, Lewan E, van den Hurk BJJM, Viterbo P, Grelle A, Lindroth A, Cienciala E, Molder M, Halldin S, Lundin LC

Abstract

The objective of the present study was to assess the performance and recent improvements of the land surface scheme used operationally in the European Centre for Medium-Range Weather Forecasts (ECMWF) in a Scandinavian boreal forest climate/ecosystem. The previous (the 1999 scheme of P. Viterbo and A. K. Betts) and the new (Tiled ECMWF Surface Scheme for Exchange Processes over Land, TESSEL) surface schemes were validated by single-column runs against data from NOPEX (Northern Hemisphere Climate-Processes Land-Surface Experiment). Driving and validation datasets were prepared for a 3-yr period (1994-96). The new surface scheme, with separate surface energy balances for subgrid fractions (tiling), improved predictions of seasonal as well as diurnal variation in surface energy fluxes in comparison with the old scheme. Simulated wintertime evaporation improved significantly as a consequence of the introduced additional aerodynamic resistance for evaporation from snow lying under high vegetation. Simulated springtime evaporation also improved because the limitation of transpiration in frozen soils was now accounted for. However, downward sensible heat flux was still underestimated during winter, especially at nighttime, whereas soil temperatures were underestimated in winter and overestimated in summer. The new scheme also underestimated evaporation during dry periods in summer, whereas soil moisture was overestimated. Sensitivity tests showed that further improvements of simulated surface heat fluxes and soil temperatures could be obtained by calibration of parameters governing the coupling between the surface and the atmosphere and the ground heat flux, and parameters governing the water uptake by the vegetation. Model performance also improved when the seasonal variation in vegetation properties was included

Published in

Journal of Applied Meteorology
2003, Volume: 42, number: 1, pages: 95-112
Publisher: AMER METEOROLOGICAL SOC

      SLU Authors

    • Grelle, Achim

      • Department of Ecology, Swedish University of Agricultural Sciences
      • Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences

      • UKÄ Subject classification

      Environmental Sciences related to Agriculture and Land-use
      Forest Science

      Publication identifier

      DOI: https://doi.org/10.1175/1520-0450(2003)042<0095:BFSPIT>2.0.CO;2

      Permanent link to this page (URI)

      https://res.slu.se/id/publ/770