The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Vanessa Haverd, Ray Leuning, David Griffith, Eva van Gorsel, Matthias Cuntz February 06, 2008

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Lagrangian Dispersion in Plant Canopies z 0 = 0 SjSj z m = h c z j-1 zjzj z ref ; c ref z i ; c i Dispersion Matrix, D Calculated using Lagrangian Dispersion theory (e.g. LNF, Raupach 1989) Inputs are turbulence statistics Standard deviation of vertical wind velocity:  w (measured) Lagrangian Timescale: T L (parameterised)

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Lagrangian Dispersion in Plant Canopies: Applications AssumedInferredApplication 1.D, ScLand-surface scheme calculations of in-canopy T, CO 2, H 2 O (eg CABLE) 2.D, cSSource/sink partitioning between ground and veg (eg. Leuning et al. 2000; Denmead et al. 2000) 3.c, SDConstraint of in-canopy Lagrangian timescale (This work! )

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Parameterisations of Lagrangian Timescale,  L

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Approach(1) SjSj Turbulence stats (obs) cost c i - c ref (obs) param opt D ij c i – c ref (predicted) SVAT model ww Prior  L LL Turbulent transfer Model (LNF)

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Approach(2) SVAT modelparam opt Met data Net fluxes (obs) Stomatal conductance/ photosyn params, a 1, D s,0, V c,max,0,  Leaf angle distribution parameter,  L Net fluxes (predicted) cost Source/sink distribution S j P gap (obs) P gap (predicted) Leaf area density distribution Fixed parameters

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions SVAT model, applied to Tumbarumba Multilayer canopy model (Wang and Leuning, 1998) Sunlit/ shaded leaf model coupling stomatal conductance, photosynthesis and energy partitioning Radiation distribution in the canopy (3 wave-bands) Recent additions Soil and biomass respiration rates (Keith et al. 2008) Heat storage fluxes in the canopy air and biomass (Haverd et al. 2007) Multilayer soil model with coupled heat/moisture fluxes and litter

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Measurements 70 m tower in 40 m temperate Eucalyptus forest (Tumbarumba Ozflux site) Continuous measurements at 70 m: eddy fluxes (H, E, CO 2 ) R net upward and downward solar radiation fluxes met data Continuous temperature and water vapour profiles 2 week campaign (Nov 2006) 7 tower inlets to 2 Fourier transform infrared spectrometers Hourly measurements of CO 2, water vapour Ground-based Lidar measurements of direct beam transmission probability (P gap ) and hence foliage density profile. (Jupp et al. 2008) Array of 3D sonic anemometers   w profile, Eulerian timescale. Chamber measurements of CO 2 and CH 4 soil fluxes (Fest et al. 2008)

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Measured Concentration Profiles

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Foliage Area Volume Density and P gap Jupp et al., 2008

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Hourly Net Fluxes at 70 m

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Vertical source/sink distributions

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Hourly flux partitioning between ground and vegetation

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Turbulence Statistics from Measurements

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Functional form of  L (Styles et al. 2002) c 1 →∞ ; c 2 = 0.32c 1 = 0; c 2 = 0.32 c 1 = 7.32; c 2 = 0.32

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Measured and Predicted Concentrations using prior  L (Styles et al. parameterisation)

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Measured and Predicted Concentrations using optimised  L (Styles et al. parameterisation)

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Massman and Weil parameterisation (1999)

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Measured and Predicted Concentrations using optimised  L (Styles et al. and MW parameterisations)

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Prior and Optimised Profiles of  L Styles et al. Massman and Weil Piecewise linear

CSIRO. The Lagrangian time scale for turbulent transport in forest canopies, determined from measured fluxes and concentrations and modelled source distributions Summary T L required to calculate dispersion matrix linking in-canopy source/sinks to concentrations. High uncertainty in T L because it cannot be measured directly We have estimated the profile of T L using Hourly vertical profiles of θ, [CO 2 ], [H 2 O] SVAT model predictions of source/sink distributions and uncertainites, constrained by meaurements : Net fluxes above canopy Chamber measurements of CO2 ground fluxes P gap from ground-based Lidar Result: with c 1 = 8.4±3.2; c 2 = 0.49±0.05 decreases with canopy depth 1.7 times higher than prior estimate based on T E

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