getPscale: calculate Pscale

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

calculate Pscale

Description

calculates Pscale according to eqn 7 in Mahadevan et al, 2007

Usage

getPscale(LSWI, phen)

Arguments

LSWI	1xN numeric vector; land surface water index
phen	1xN factor vector; MODIS phenology (factor with levels ginc, gmin, gmax, gdec)

Details

The levels of phen are abbreviations: ginc - "onset greenness increase", gmin - "onset greenness minimum", gmax - "onset greenness maximum", gdec - "onset greenness decrease". This phenology dynamics classification scheme is explained more fully in Zhang et al (2003).

Value

Pscale term in VPRM equation (eqn 7 in Mahadevan et al, 2008)

Author(s)

Timothy W. Hilton

References

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.

Xiaoyang Zhang, Mark A. Friedl, Crystal B. Schaaf, Alan H. Strahler, John C.F. Hodges, Feng Gao, Bradley C. Reed, Alfredo Huete, Monitoring vegetation phenology using MODIS, Remote Sensing of Environment, Volume 84, Issue 3, March 2003, Pages 471-475, ISSN 0034-4257, http://dx.doi.org/10.1016/S0034-4257(02)00135-9.

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)
pfa_df <- as.data.frame( pfa_dd )
pscale <- getPscale( pfa_df[['LSWI']], pfa_df[['phen']] )

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