SOIL –VEGETATION‐ATMOSPHERE TRANSFER SYMBOLS AND VARIABLES: ET = Evapotranspiration I0 = Solar constant [W/m2] δ = solar declination z = solar zenith angle hs = solar altitude az = solar azimut Rsw= shortwave radiation [W/m2] rE = Earth Radius Ri =Incident Radiation Rr =Reflected Radation Ra=Absorbed Radiation Rt =Transmitted Radiation Rdir = Direct shortwave radiation [W/m2] Rdif = Diffuse shortwave radiation [W/m2] Rtot= total radiation [W/m2] a = absorptivity ε= emissivity λ = wawelenght T= Temperature σ=5.67 10‐8 [W m‐2 K‐4] Stefan‐Boltzmann constant α = albedo [‐] RSW = Shortwave radiation [W/m2] RLW = Longwave radiation [W/m2] K(N): cloud cover correction for incoming longwave radiation [‐] εcs = clear sky emissivity of the atmosphere [‐] εs = surface emissivity [‐] 1 Ta= Air Temperature [K] or [°C] Ts= Surface Temperature [K] or [°C] ea= Water Vapor pressure [Pa] or [bar] Rn = Net radiation [W/m2] λ E= latent heat [W/m2] H = sensible heat [W/m2] G = Ground heat flux [W/m2] LpFp = Energy used by photosynthesis [W/m2] Ah = Advected heat [W/m2] U= Energy stored in the system [J/m2] ‐‐‐ D: molecular diffusivity [m2 s‐1] μ: dynamic viscosity [Pa s] Kt: thermal conductivity [W m‐1 K‐1] Ws = wind speed [m/s] CA = generic concentration E = evaporation flux u = horizontal component wind speed [m/s] v= horizontal component wind speed [m/s] w=vertical component wind speed [m/s] q= specific humidity [g/kg] or [‐] τ = Momentum flux Cp = heat capacity at constant pressure [ J /kg K] ρ = density or air [kg/m3] ABL = Atmospheric boundary layer SBL = Surface boundary layer z0 = roughness height [m] CH: Heat transfer coefficient Æ Stanton Number 2 CD: Momentum transfer coefficient Æ Drag Number CE: Water vapor transfer coefficient Æ Dalton Number ra = aerodynamic resistance [s/m] u* = friction velocity [m/s] τ0 = Sink of momentum flux at the surface k= 0.41 von Karman constant d= displacement height[m] z0m = sink position for momentum [m] z0v = sink position for water vapor [m] z0h = sink position for sensible heat [m] z = reference height [m] ‐‐‐‐ esat= Water vapor pressure at saturation [Pa] or [bar] T = transpiration [mm/h] or [mm/day] or [mm/year] or [kg/m^2 s] ET = Evapotranspiration [mm/h] or [mm/day] or [mm/year] or [kg/m^2 s] E = evaporation [mm/h] or [mm/day] or [mm/year] or [kg/m^2 s] λ = latent heat of vaporization P = atmospheric pressure [Pa] or [bar] Qi = incoming discharge Qo = outgoing discharge Bo = Bowen ratio γ = psychrometric constant Δ = derivative of the water vapor pressure at saturation vs. temperature βR = Limiting factor for potential evaporation LAI = Leaf Area Index rs =stomatal resistence [s/m] rc =canopy resistence [s/m] βRT = Limiting factor for potential evapotranspiration 3 SOIL –HYDROLOGY SYMBOLS AND VARIABLES: ΔV = Representative Elementary Volume of soil Va= Volume of air in the soil Vw= Volume of water in the soil Vs= Volume of solid particles in the soil n= soil porosity [‐] θ = volumetric water content in the soil [‐] or [m^3/m^3] or θR = residual water content [‐] θSAT = saturated water content [‐] ψ= soil water potential [kPa] or [MPa] or [mm] or [m] or [bar] S = degree of saturation [‐] Se= Effective saturation [‐] ψb= Air entry soil water potential [kPa] λ0 = Pore‐size distribution parameter [‐] m,n α = Van Genuchten equation parameters h = hydraulic head [m] or [Pa] z = elevation (gravitational head) [m] or [Pa] q= Water flow (Discharge per unit of area) [m/s] or [mm/h]; Ksat = saturated hydraulic conductivity [m/s] or [mm/h] KH = horizontal hydraulic conductivity [m/s] or [mm/h] Kv = vertical hydraulic conductivity [m/s] or [mm/h] ar = anisotropy ratio [‐] D= soil water diffusivity [m2/s ] or [mm2/h] fc = infiltration capacity [mm/h] or [m/s] Fc = cumulative infiltration capacity [mm] or [m] 4 RH = infiltration excess runoff [mm/h] or [m/s] A= sorptivity [m/s0.5] f0 = initial rate of infiltration [mm/h] or [m/s] ff = final rate of infiltration [mm/h] or [m/s] f = actual infiltration [mm/h] or [m/s] F = cumulative actual infiltration [mm] or [m] tp = ponding time [h] or [s] t0 =lag time [h] or [s] t* = Fictitious time required to produce the same infiltration than potential conditions [h] or [s] RD = saturation excess runoff [mm/h] or [m/s] Zsoil = soil depth [m] or [mm] Smax = maximum soil storage capacity [m] or [mm] K̂ = catchment scale infiltration capacity [mm/h] or [m/s] ϕ = runoff coefficient [‐] Q= discharge [m3/s] or [mm/h] or [mm/d] T= lateral transmissivity [mm2/h] or [m2/s] 5