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Theoretical and Applied Climatology

, Volume 72, Issue 3–4, pp 231–243 | Cite as

Increased heat fluxes near a forest edge

  • W. Klaassen
  • P. B. van Breugel
  • E. J. Moors
  • J. P. Nieveen

Summary

¶Observations of sensible and latent heat flux above forest downwind of a forest edge show these fluxes to be larger than the available energy over the forest. The enhancement averages to 56 W m−2, or 16% of the net radiation, at fetches less than 400 m, equivalent to fetch to height ratios less than 15. The enhancement of turbulent energy fluxes is explained by advection and increases with the difference in temperature and humidity of the air over the upwind area as compared to the forest. The relatively high temperature and humidity of the upwind air are not caused by high surface heat fluxes, but are explained by the relatively low aerodynamic roughness of the upwind surface. Although the heat fluxes over forest are enhanced, the momentum fluxes are almost adjusted to the underlying forest. The different behaviour of heat and momentum fluxes is explained by absorption of momentum by pressure gradients near the forest edge. It is concluded that fetch requirements to obtain accurate surface fluxes from atmospheric observations need to be more stringent for scalar fluxes as compared to momentum fluxes.

Keywords

Heat Flux Advection Latent Heat Flux Forest Edge Surface Heat Flux 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag/Wien 2002

Authors and Affiliations

  • W. Klaassen
    • 1
  • P. B. van Breugel
    • 2
  • E. J. Moors
    • 3
  • J. P. Nieveen
    • 4
  1. 1.Department of Marine Biology, University of Groningen, Haren (Gr.), The NetherlandsNL
  2. 2.Air Research Laboratory (LLO), RIVM, Bilthoven, The NetherlandsNL
  3. 3.Alterra (SC-DLO), AC Wageningen, The NetherlandsNL
  4. 4.Meteorology and Air Quality Group, Wageningen Agricultural University, The NetherlandsNL

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