Advanced modeling and experimental analysis of the flow field above and within the forest canopy at the Wind River Canopy Crane AmeriFlux site

In a joint project between the University of Georgia, Griffin (UGA), the Universidad Autonoma Agraria Antonio Narro (UAAAN), and the University of California, Davis (UCD), a modeling and planetary boundary layer field study was carried out within and above a 67 m tall, old growth forest. The experimental work focused on the wind velocity field above and within the Wind River Canopy Crane Research Facility AmeriFlux site. The modeling work used the UCD Advanced Canopy Atmosphere Soil Algorithm (ACASA) coupled with the regional scale models MM5 and the NCAR WRF model. The objectives were to characterize and describe the main characteristics of the wind flow field above the forest canopy its relationship to atmospheric stability, wind profile and eddy covariance sensible heat flux. A Scintec SODAR was set up in the jib of the crane to collect wind speed and direction data up to a height of 500 m with a 10 m vertical resolution, while simlutaneous 10 Hz data (wind velocity, sonic temperature, water vapor, and carbon dioxide) were taken just above the canopy height at 70 m and below the main canopy at 3 m. During some intensive campaign periods, tethersondes were used to gather temperature, humidity, wind speed, and carbon dioxide concentrations above the canopy. Data indicated the diurnal flow patterns, and the possibility of a low-level nocturnal jet. During the night, turbulence was greatest above the canopy and damped out within the upper canopy, but during the day turbulence was greater in the upper canopy than above.