HR: 17:00h
AN: B42D-04    [PDF]
TI: How Complex Must the Parameterization of Canopy Turbulent Transport Be to Capture Biophysical Sources and Sinks?
AU: * Juang, J
EM: jj19@duke.edu
AF: 1. Nicholas School of the Environment and Earth Sciences, Duke University, 1Nicholas School of the Environment and Earth Sciences, Box90328, Duke University, Durham, NC 27708 United States
AU: Katul, G
EM: gaby@duke.edu
AF: 1. Nicholas School of the Environment and Earth Sciences, Duke University, 1Nicholas School of the Environment and Earth Sciences, Box90328, Duke University, Durham, NC 27708 United States
AU: Katul, G
EM: gaby@duke.edu
AF: 2 Department of Civil and Environmental Engineering, Duke University, 2Department of Civil and Environmental Engineering, Box90287, Duke University, Durham, NC 27708 United States
AU: Siqueira, M
EM: mbs4@duke.edu
AF: 1. Nicholas School of the Environment and Earth Sciences, Duke University, 1Nicholas School of the Environment and Earth Sciences, Box90328, Duke University, Durham, NC 27708 United States
AU: Stoy, P
EM: pcs3@duke.edu
AF: 1. Nicholas School of the Environment and Earth Sciences, Duke University, 1Nicholas School of the Environment and Earth Sciences, Box90328, Duke University, Durham, NC 27708 United States
AB: The exchange of scalars and momentum through canopy volume exerts control over almost all aspects of the canopy microenvironment, which in turn, plays a significant role in regulating biologically controlled scalar sources and sinks. This study is the first to rigorously explore how detailed the parameterization of the turbulent transport mechanism must be to accurately predict source-sink and flux profile distributions within the canopy across a wide range of leaf area density, climatic, and environmental variables. Towards this end, detailed ecophysiological and radiative transfer schemes are coupled to higher-order closure models to capture the ­two-way interaction­" between the canopy and its microclimate. The turbulent transport schemes consider range from first- to third-order closure approximations assuming both thermally stratified and neutral flows. The data sets used in the model calculations include long-term within-canopy scalar concentration, and temperature profiles collected along with sensible heat, latent heat, and CO2 fluxes above the canopy. These measurements, collected from September 1998 to date, are part of an on-going long-term flux monitoring initiative (AmeriFlux) in an even-aged pine forest near Durham, North Carolina. Current model results suggest that first-order closure model, corrected for atmospheric stability, are sufficient to capture much of the scalar source-sink variations within the canopy as well as fluxes above the canopy; second-order closure models are necessary to accurately reproduce the scalar profiles within the canopy; and third-order closure models are no better than second order in terms of overall predictive skills for scalar profiles and fluxes. Our model calculations also suggest that accounting for atmospheric stability is more important than increasing the closure order for improving source-sink, flux, and scalar concentration predictive skills.
DE: 0315 Biosphere/atmosphere interactions
DE: 3322 Land/atmosphere interactions
DE: 3337 Numerical modeling and data assimilation
SC: Biogeosciences [B]
MN: 2003 Fall Meeting