vprm_calc_NEE: calculate VPRM NEE

In Timothy-W-Hilton/VPRMLandSfcModel: R implementation of VPRM with parameter estimation

calculate VPRM NEE

Description

calculates VPRM net ecosystem exchange (NEE) according to eqn 12 in Mahadevan et al, 2007

Usage

vprm_calc_NEE(
  driver_data,
  lambda_param = NULL,
  alpha_param = NULL,
  beta_param = NULL,
  PAR_0_param = NULL,
  model_form = "Mahadevan07"
)

Arguments

driver_data	May be a VPRM_driver_data object or a data frame. If a data frame, driver_data must contain the variables Tscale, Pscale, Wscale, EVI, PAR, and Tresp. The variables lambda, alpha, beta, and PAR_0 are optional (see 'details').
lambda_param	numeric, optional; VPRM parameter: maximum light use efficiency.
alpha_param	numeric, optional; VPRM parameter (slope of respiration with respect to temperature)
beta_param	numeric, optional; VPRM parameter (basal respiration rate)
PAR_0_param	numeric, optional; VPRM parameter (LUE half-saturation value)
model_form	string, optional; form of VPRM model to use. Options are "Mahadevan07" (default) to use the VPRM formulation of Mahadevan et al. (2007), or "urban" to use the urbanVPRM formulation of Hardiman et al. (2017). If set to "urban", the driver data must include variables ISA proportion (impervious surface area, 0.0 to 1.0) and refEVI (reference EVI).

Details

Arguments lambda, alpha, beta, and PAR_0 may be omitted from the function call. In this case they must be present as variables in data frame driver_data. If any of these four parameters are present in driver_data *and* specified as parameters in the function call the function parameter values will be used and the values in driver_data will be ignored. If specifed as function parameters lambda, alpha, beta, and PAR_0 may be single values or numeric vectors the same length as the number of observations in driver_data.

The Tresp variable in driver_data is the temperature used to calculate respiration. Tresp should be max(Tair, Tlow), where Tair is the air temperature (deg C) and Tlow is the minimum air temperature (deg C) for respiration. This is explained more fully in Mahadevan et al (2008) section 2.2.

Value

vector of same length as number of rows in driver_data containin VPRM NEE [umol m-2 s-1]

Author(s)

Timothy W. Hilton

References

Hilton, T. W., Davis, K. J., Keller, K., and Urban, N. M.: Improving North American terrestrial CO2 flux diagnosis using spatial structure in land surface model residuals, Biogeosciences, 10, 4607-4625, doi:10.5194/bg-10-4607-2013, 2013.

Mahadevan, P., Wofsy, S., Matross, D., Xiao, X., Dunn, A., Lin, J., Gerbig, C., Munger, J., Chow, V., and Gottlieb, E.: A satellite-based biosphere parameterization for net ecosystem CO2 exchange: Vegetation Photosynthesis and Respiration Model (VPRM), Global Biogeochem. Cy., 22, GB2005, doi:10.1029/2006GB002735, 2008.

Hardiman, B. S., Wang, J. A., Hutyra, L. R., Gately, C. K., Getson, J. M., & Friedl, M. A. (2017). Accounting for urban biogenic fluxes in regional carbon budgets. Science of The Total Environment, 592, 366–372. https://doi.org/10.1016/j.scitotenv.2017.03.028

Examples

data(Park_Falls)
pfa_dd <- VPRM_driver_data(name_long="Park Falls",
                           name_short = "US-PFa",
                           lat=45.9459,
                           lon=-90.2723,
                           PFT='MF',
                           tower_date=PFa_tower_obs[['date']],
                           NEE_obs=PFa_tower_obs[['FC']],
                           T=PFa_tower_obs[['TA']],
                           PAR=PFa_tower_obs[['PAR']],
                           date_nir = PFa_refl[['date']],
                           rho_nir=PFa_refl[['nir']],
                           date_swir = PFa_refl[['date']],
                           rho_swir = PFa_refl[['swir']],
                           date_EVI = PFa_evi[['date']],
                           EVI=PFa_evi[['evi']],
                           phen=NA)
data(VPRM_parameters)
attach(all_all_VPRM_parameters)
NEE <- vprm_calc_NEE(pfa_dd,
                     lambda=lambda, PAR_0=PAR_0, alpha=alpha, beta=beta)

Timothy-W-Hilton/VPRMLandSfcModel documentation built on July 29, 2023, 8:43 p.m.