Boundary-Layer Meteorology

, Volume 156, Issue 2, pp 231–251 | Cite as

Field Observations of Canopy Flows over Complex Terrain

  • Eleanor R. Grant
  • Andrew N. Ross
  • Barry A. Gardiner
  • Stephen D. Mobbs
Article

Abstract

The investigation of airflow over and within forests in complex terrain has been, until recently, limited to a handful of modelling and laboratory studies. Here, we present an observational dataset of airflow measurements inside and above a forest situated on a ridge on the Isle of Arran, Scotland. The spatial coverage of the observations all the way across the ridge makes this a unique dataset. Two case studies of across-ridge flow under near-neutral conditions are presented and compared with recent idealized two-dimensional modelling studies. Changes in the canopy profiles of both mean wind and turbulent quantities across the ridge are broadly consistent with these idealized studies. Flow separation over the lee slope is seen as a ubiquitous feature of the flow. The three-dimensional nature of the terrain and the heterogeneous forest canopy does however lead to significant variations in the flow separation across the ridge, particularly over the less steep western slope. Furthermore, strong directional shear with height in regions of flow separation has a significant impact on the Reynolds stress terms and other turbulent statistics. Also observed is a decrease in the variability of the wind speed over the summit and lee slope, which has not been seen in previous studies. This dataset should provide a valuable resource for validating models of canopy flow over real, complex terrain.

Keywords

Atmospheric boundary layer Complex terrain Flow separation  Forest canopy Hills 

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Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • Eleanor R. Grant
    • 1
    • 2
  • Andrew N. Ross
    • 1
  • Barry A. Gardiner
    • 3
    • 4
    • 5
  • Stephen D. Mobbs
    • 6
  1. 1.School of Earth and Environment, Institute for Climate and Atmospheric ScienceUniversity of LeedsLeedsUK
  2. 2.British Antarctic SurveyHigh CrossCambridgeUK
  3. 3.Forest ResearchNorthern Research StationMidlothianScotland, UK
  4. 4.INRA, UMR 1391 ISPAVillenave D’OrnonFrance
  5. 5.Bordeaux Sciences Agro, UMR 1391 ISPAGradignanFrance
  6. 6.National Centre for Atmospheric Science and School of Earth and EnvironmentUniversity of LeedsLeedsUK

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