Turbulence and wind above and within the forest canopy
The forest has a strong influence on vertical profiles of micrometeorological variables within and above the canopy. Especially pronounced variations of all variables between ground level and crown top are primarily generated by the forest architecture. When wind encounters forest canopy, the drag of the foliage removes mean momentum of wind producing turbulent eddies. Dissipation of mean flow kinetic energy within and below the forest crown usually has been described through vertical gradient of wind speed. The accuracy of within-canopy wind profile calculation is related to assumed forest architecture and to adopted approach for parameterization of momentum turbulent fluxes. This chapter is focused on forest architecture and on turbulence produced by friction exerted when air flow encounters forest canopy. An overview of different approaches oriented towards their parameterization (forest architecture) and modelling (turbulence) is presented.