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Improvement of surface flux parametrizations with a turbulence‐related length
Author(s) -
Yang K.,
Koike T.,
Fujii H.,
Tamagawa K.,
Hirose N.
Publication year - 2002
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1256/003590002320603548
Subject(s) - parametrization (atmospheric modeling) , flux (metallurgy) , turbulence , surface (topology) , heat flux , surface roughness , length scale , physics , stanton number , roughness length , plateau (mathematics) , heat transfer , meteorology , mechanics , thermodynamics , materials science , geometry , mathematics , wind speed , optics , mathematical analysis , reynolds number , wind profile power law , metallurgy , radiative transfer
In surface flux parametrizations, aerodynamic roughness length z m 0 , and thermal roughness length z h 0 , are used to account for different resistances for momentum transfer and heat transfer. This paper introduces a turbulence‐related length h T and parametrizes the quantity kA −1 =ln( h T/ z h 0 ) in order to estimate z h 0 . Based on data at three sites on the Tibetan Plateau, a general formula for kA −1 is obtained for the surfaces covered by bare soil or partially covered by very short vegetation. A surface flux parametrization with this formula provides better estimates of heat flux than either profile flux parametrization or surface flux parametrization with kB −1 (i.e. ln( z m 0 / z h 0 )). Therefore, the use of a reasonable length to scale z h 0 can contribute to the improvement of surface flux parametrizations. Copyright © 2002 Royal Meteorological Society