Anomalies in flux-gradient relationships over forest Export

@article{citeulike:5873279, abstract = {Simultaneous profile and eddy correlation flux data gathered over Thetford Forest, U.K., have been analysed to find values of the vertical turbulent diffusivitiesK M,K H andK E (for momentum, heat and water vapour transfer, respectively) at a reference heightz R, nine roughness lengths above the zero-plane displacementd. The results show: (i), that values ofK M over the forest are not significantly different from these predicted by semiempirical diabatic influence functions appropriate to much smoother surfaces such as short grass; and (ii), thatK H andK E exceed their values predicted from the semiempirical functions by an average factor of 2 or more in unstable, near neutral and slightly stable conditions. These conclusions are strongly dependent on the assumed behaviour ofd, here taken as 0.76 tree heights, independent of both property and stability. Consideration is given to an alternative analysis procedure, in which values of the zero-plane displacementsd H andd E for heat and water vapour respectively, are obtained from the data by assumingK H andK E to be given by semiempirical diabatic influence functions; this procedure is shown to be unacceptable on both practical and physical grounds. To account for the anomalies inK H andK E, a mechanism is proposed in which the horizontally inhomogeneous temperature structure of the canopy causes free convection to be maintained by discrete; localized heat sources and/or sinks, effectively enhancing turbulent transport processes even in nearneutral conditions.}, author = {Raupach, M.}, citeulike-article-id = {5873279}, citeulike-linkout-0 = {http://dx.doi.org/10.1007/BF03163564}, citeulike-linkout-1 = {http://www.springerlink.com/content/8t1t58753121g487}, day = {1}, doi = {10.1007/BF03163564}, journal = {Boundary-Layer Meteorology}, keywords = {abl, canopy, flux, stratified, tbl}, month = {December}, number = {4}, pages = {467--486}, posted-at = {2009-10-07 17:01:26}, priority = {1}, title = {Anomalies in flux-gradient relationships over forest}, url = {http://dx.doi.org/10.1007/BF03163564}, volume = {16}, year = {1979} }

TY - JOUR ID - citeulike:5873279 L3 - citeulike-article-id:5873279 N2 - Simultaneous profile and eddy correlation flux data gathered over Thetford Forest, U.K., have been analysed to find values of the vertical turbulent diffusivitiesK M,K H andK E (for momentum, heat and water vapour transfer, respectively) at a reference heightz R, nine roughness lengths above the zero-plane displacementd. The results show: (i), that values ofK M over the forest are not significantly different from these predicted by semiempirical diabatic influence functions appropriate to much smoother surfaces such as short grass; and (ii), thatK H andK E exceed their values predicted from the semiempirical functions by an average factor of 2 or more in unstable, near neutral and slightly stable conditions. These conclusions are strongly dependent on the assumed behaviour ofd, here taken as 0.76 tree heights, independent of both property and stability. Consideration is given to an alternative analysis procedure, in which values of the zero-plane displacementsd H andd E for heat and water vapour respectively, are obtained from the data by assumingK H andK E to be given by semiempirical diabatic influence functions; this procedure is shown to be unacceptable on both practical and physical grounds. To account for the anomalies inK H andK E, a mechanism is proposed in which the horizontally inhomogeneous temperature structure of the canopy causes free convection to be maintained by discrete; localized heat sources and/or sinks, effectively enhancing turbulent transport processes even in nearneutral conditions. IS - 4 JF - Boundary-Layer Meteorology EP - 486 TI - Anomalies in flux-gradient relationships over forest VL - 16 SP - 467 KW - abl KW - canopy KW - flux KW - stratified KW - tbl AU - Raupach, M PY - 1979/12/01/ UR - http://dx.doi.org/10.1007/BF03163564 ER -