Variables#

This page helps you translate measurements into model inputs and interpret simulation results. Names are case-sensitive: T is air temperature, while Tₗ is leaf temperature.

Common leaf variables#

Name	Meaning	Unit
`Tₗ`	Leaf temperature	°C
`A`	Net CO₂ assimilation	µmol CO₂ m⁻² s⁻¹
`Gₛ`	Stomatal conductance to CO₂	mol CO₂ m⁻² s⁻¹
`Cₛ`, `Cᵢ`	CO₂ concentration at the leaf surface and inside the leaf	µmol mol⁻¹
`Dₗ`	Leaf-to-air vapour pressure difference	kPa
`aPPFD`	Absorbed photosynthetic photon flux density	µmol photons m⁻² s⁻¹
`Ra_SW_f`	Absorbed shortwave radiation	W m⁻²
`Rn`	Net radiation	W m⁻²
`H`, `λE`	Sensible and latent heat fluxes	W m⁻²
`d`	Characteristic leaf dimension	m

The area in these leaf-model quantities is leaf area. Canopy light models use ground area for their radiation outputs; see Light interception before connecting them to leaf models. The Micro-climate page describes weather variables.

Find the inputs and outputs of a model#

A variable can be an input of one model and an output of another. For example, a standalone Medlyn model needs assimilation A as an input, while a coupled photosynthesis model calculates it.

julia

using PlantBiophysics, PlantSimEngine
model = Medlyn(0.03, 12.0)
(inputs=inputs(model), outputs=outputs(model))

(inputs = (:Dₗ, :Cₛ, :A), outputs = (:Gₛ,))

Supply the inputs that are not calculated by another model in the simulation. The model pages describe their parameters, expected inputs, and weather requirements; Design explains how they fit into a simulation.

Full variable list#

Use variables(PlantBiophysics) to look up the package's variable names, descriptions, and units:

julia

variables(PlantBiophysics)

37×3 DataFrame

Row	Variable	Description	Unit
	String15	String	String31
1	A	carbon assimilation	μmol[CO₂] m⁻² s⁻¹
2	Cᵢ	Intercellular CO₂ concentration	mol[CO₂] m⁻² s⁻¹
3	Cₐ	Air CO₂ concentration	mol[CO₂] m⁻² s⁻¹
4	Cₛ	Air CO₂ concentration at the leaf surface	mol[CO₂] m⁻² s⁻¹
5	Dₗ	Vapour pressure difference between the surface and the saturated air vapour pressure	kPa
6	Gbc	Leaf boundary conductance for CO₂ (one-sided)	mol[CO₂] m⁻² s⁻¹
7	Gbₕ	Leaf boundary conductance for heat (one-sided)	m s⁻¹
8	Gₛ	stomatal conductance for CO₂	mol[CO₂] m⁻² s⁻¹
9	H	Sensible heat flux	W m⁻²
10	P	Air pressure	kPa
11	Ra_LW_f	Absorbed longwave radiation flux (TIR) also called net flux between the object and the atmosphere	W m⁻²
12	Ra_NIR_f	Absorned net NIR radiation flux	W m⁻²
13	Ra_PAR_f	Absorned net PAR radiation flux	W m⁻²
14	Ra_SW_f	Absorned net shortwave radiation (PAR + NIR). Often computed from a light interception model	W m⁻²
15	Rbₕ	Leaf boundary resistance for heat (one-sided)	m s⁻¹
16	Rh	Relative humidity	0-1
17	Ri_NIR_f	Incoming NIR flux	W m⁻²
18	Ri_PAR_f	Incoming PAR flux	W m⁻²
19	Ri_SW_f	Incoming short wave radiation flux	W m⁻²
20	Ri_TIR_f	Incoming TIR flux	W m⁻²
21	T	Air temperature	Celsius degree
22	Tₗ	Leaf temperature	Celsius degree
23	VPD	Vapor pressure deficit	kPa
24	Wind	wind speed	m s⁻¹
25	aPPFD	Absorbed Photosynthetic Photon Flux Density	μmol[photon] m⁻² s⁻¹
26	clearness	Sky clearness	0-1
27	d	Characteristic dimension e.g. leaf width	meter
28	duration	Time duration e.g. for a time-step	seconds
29	e	Vapor pressure	kPa
30	eₛ	Saturated vapor pressure	kPa
31	sky_fraction	View factor between the object and the sky for both faces (0-2)	-
32	Δ	Slope of the saturation vapor pressure at air temperature	-
33	γ	Psychrometer "constant"	kPa K⁻¹
34	ε	Atmosphere emissivity	0-1
35	λ	Latent heat of vaporization	J kg⁻¹
36	λE	Latent heat flux	W m⁻²
37	ρ	Air density	kg m⁻³

On this page

Variables​#

Common leaf variables​#

Find the inputs and outputs of a model​#

Full variable list​#

Variables#

Common leaf variables#

Find the inputs and outputs of a model#

Full variable list#