Jarvis Stewart#
- class abcmodel.land.biosphere.jarvis_stewart.JarvisStewartState(rs, wl, cliq, wCO2, cveg, wltend=<factory>)[source]#
Bases:
AbstractBiosphereStateJarvis-Stewart biosphere state.
- rs: Array#
Surface resistance [s m-1].
- wl: Array#
Canopy water content [m].
- cliq: Array#
Wet fraction of canopy [-].
- wCO2: Array#
Kinematic CO2 flux [mol m-2 s-1].
- cveg: Array#
Vegetation fraction [-].
- wltend: Array#
Canopy water content tendency [m].
- class abcmodel.land.biosphere.jarvis_stewart.JarvisStewartModel(rsmin=110.0, lai=2.0, gD=0.0, cveg=0.85, wmax=0.0002, wwilt=0.171, wfc=0.323, w2=0.21)[source]#
Bases:
AbstractBiosphereModel[JarvisStewartState]Jarvis-Stewart biosphere model with empirical surface resistance.
- Parameters:
rsmin (
float) – minimum stomatal resistance [s m-1]. Default is 110.0.lai (
float) – leaf area index [m2 m-2]. Default is 2.0.gD (
float) – canopy rad extinction coefficient [-]. Default is 0.0.wmax (
float) – maximum water storage capacity of the canopy [m]. Default is 0.0002.wwilt (
float) – soil moisture content at wilting point [m3 m-3]. Default is 0.171.wfc (
float) – soil moisture content at field capacity [m3 m-3]. Default is 0.323.w2 (
float) – soil moisture content at the second layer [m3 m-3]. Default is 0.21.
- init_state(rs=1000000.0, wl=0.0, cliq=0.0, wCO2=0.0)[source]#
Initialize the biosphere state.
- Parameters:
rs (
float) – Surface resistance [s m-1]. Default is 1.0e6.wl (
float) – Canopy water content [m]. Default is 0.0.cliq (
float) – Wet fraction of canopy [-]. Default is 0.0.wCO2 (
float) – Kinematic CO2 flux [mol m-2 s-1]. Default is 0.0.cveg – vegetation fraction [-]. Default is 0.85.
- Returns:
The initialized JarvisStewartState.
- compute_f1(in_srad)[source]#
Compute the radiation stress factor
f1.Notes
The radiation factor follows the Jarvis (1976) formulation:
\[f_1 = \frac{1}{\min\!\left(1,\, \dfrac{0.004\,R_s + 0.05}{0.81\,(0.004\,R_s + 1)}\right)}\]where \(R_s\) is the incoming solar radiation.
- compute_f2(wg)[source]#
Compute the soil moisture stress factor
f2.Notes
The soil moisture factor follows the Jarvis (1976) formulation:
\[f_2 = \max\!\left(1,\, \frac{w_{\text{fc}} - w_{\text{wilt}}} {w_g - w_{\text{wilt}}}\right)\]where \(w_g\) is the surface soil moisture, \(w_{\text{fc}}\) is the field capacity and \(w_{\text{wilt}}\) is the wilting point. When the second-layer soil moisture \(w_2\) drops below the wilting point, the factor is set to a large value (effectively closing the stomata).
- compute_f3(esat, e)[source]#
Compute the vapour pressure deficit stress factor
f3.Notes
The VPD factor follows the Jarvis (1976) formulation:
\[f_3 = \exp\!\left(\frac{g_D \, D}{100}\right)\]where \(D = e_{\text{sat}} - e\) is the vapour pressure deficit, \(e_{\text{sat}}\) is the saturation vapour pressure, \(e\) is the actual vapour pressure, and \(g_D\) is the canopy radiation extinction coefficient.
- compute_f4(theta)[source]#
Compute the temperature stress factor
f4.Notes
The temperature factor follows the Jarvis (1976) formulation:
\[f_4 = \frac{1}{1 - 0.0016\,(298 - \theta)^2}\]where \(\theta\) is the potential temperature [K].
- compute_cliq(wl)[source]#
Compute the wet fraction
cliq.Notes
The wet fraction is defined as
\[c_{\text{liq}} = \frac{W_l}{\text{LAI}\cdot W_{\text{max}}},\]where \(W_l\) is the water layer depth, \(\text{LAI}\) is the leaf area index and \(W_{\text{max}}\) is the thickness of the water layer on wet vegetation. In case \(W_l > \text{LAI}\cdot W_{\text{max}}\), the wet fraction is set to 1.
References
Equation 9.19 from the CLASS book.
- compute_wltend(le_liq)[source]#
Compute the water layer depth tendency
wltend.Notes
The water layer depth tendency is the rate at which water is added to or taken from the vegetation, described by
\[\frac{\text{d} w}{\text{d} t} = -\frac{LE_{\text{liq}}}{\rho_w L_v},\]where \(LE_{\text{liq}}\) is dew, \(\rho_w\) is water density and \(L_v\) is the latent heat of vaporization.
References
Equation 9.20 from the CLASS book, with sign convention.