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Title: Explaining the convector effect in canopy turbulence by means of large-eddy simulation

Semi-arid forests are found to sustain a massive sensible heat flux in spite of having a low surface to air temperature difference by lowering the aerodynamic resistance to heat transfer ( r H) – a property called the canopy convector effect (CCE). In this work large-eddy simulations are used to demonstrate that the CCE appears more generally in canopy turbulence. It is indeed a generic feature of canopy turbulence: r H of a canopy is found to reduce with increasing unstable stratification, which effectively increases the aerodynamic roughness for the same physical roughness of the canopy. This relation offers a sufficient condition to construct a general description of the CCE. In addition, we review existing parameterizations for r H from the evapotranspiration literature and test to what extent they are able to capture the CCE, thereby exploring the possibility of an improved parameterization.
Authors:
ORCiD logo [1] ;  [1] ; ORCiD logo [1]
  1. Karlsruhe Inst. of Technology (KIT), Garmisch-Partenkirchen (Germany). Inst. of Meteorology and Climate Research. Atmospheric Environmental Research (IMK-IFU)
Publication Date:
Report Number(s):
LA-UR-17-22651
Journal ID: ISSN 1607-7938
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Hydrology and Earth System Sciences (Online)
Additional Journal Information:
Journal Name: Hydrology and Earth System Sciences (Online); Journal Volume: 21; Journal Issue: 6; Journal ID: ISSN 1607-7938
Publisher:
European Geosciences Union (EGU)
Research Org:
Karlsruhe Inst. of Technology (KIT), Garmisch-Partenkirchen (Germany); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE; German Research Foundation (DFG); Helmholtz Association (Germany)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; canopy turbulence; large eddy simulation; canopy convector effect; aerodynamic resistance
OSTI Identifier:
1369206