Table 3 Parameters and equations of the PT-JPL model8,97.

From: A spatial-temporal continuous dataset of the transpiration to evapotranspiration ratio in China from 1981–2015

Parameter

Description

Equation

fwet

Relative surface wetness

fwet = RH4

fg

Green canopy fraction

fg = fAPAR/fIPAR

fT

Plant temperature constraint

\({f}_{T}=\exp \left[-{\left(\frac{\left({T}_{a}-{T}_{opt}\right)}{{T}_{opt}}\right)}^{2}\right]\)

fSM

Soil moisture constraint

fSM = RHVPD/β

fM

Plant moisture constraint

fM = fAPAR/fAPARMAX

fAPAR

Fraction of PAR absorbed by the canopy

\({f}_{APAR}={b}_{1}(1-{e}^{-{k}_{1}\times LAI})\)

fIPAR

Fraction of PAR intercepted by the canopy

\({f}_{IPAR}={b}_{2}(1-{e}^{-{k}_{2}\times LAI})\)

  1. RH = relative humidity (%); VPD = saturation vapor pressure deficit (kPa); Ta = air temperature (°C); Topt = optimum temperature for plant growth (°C); β = sensitivity of the soil moisture constraint to VPD (kPa); fAPARmax = maximum fAPAR; b1, b2, k1, and k2 = parameters (unitless). Seven parameters need to be estimated: b1, b2, k1, k2, Topt, β, and kRn8.
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