ISSN 1002-1027  CN 11-2952/G2

Acta scientiarum naturalium Universitatis Pekinensis

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Turbulence Length Scales, Dissipation Rates and Structure Parameters above the Forest Canopy

LIU Shuhua1,2, HU Fei2, LIU Huizhi2, XU M3, ZHU Tingyao4, JIN Changjie4   

  • Received:2002-03-29 Online:2003-01-20 Published:2003-01-20

Abstract: The turbulent data were measured using three-dimensional sonic anemometers/thermometers above a forest canopy, in the Changbai Mountains of northeast China. Turbulence length scales, dissipation rates and structure parameters above the forest canopy were calculated using the eddy correlation method. Results show that the turbulence characteristic length scales for momentum are negative interrelated with Z/L number; the turbulence characteristic length scales for heat is positive interrelated with Z/L number in unstable air and that is negative interrelated with Z/L number in stable air. The agreement between the momentum and heat dissipation rates calculated directly from the w spectrum(the turbulence spectral method)and indirectly from equations(15)(16)are quite good. The dimensionless turbulence structure functions C2vz2/3σw-2 and C2Tz2/3σT-2 are functions of Richardson number in stable and unstable air. Turbulence structure parameters C2T has a direct linear bearing on the sensible heat flux w'T'.