surface_temp

Author:

 Greg O'Donnell

Date:

 September 9, 1997

Description:

This routine computes the surface energy balance for the full energy VIC model when there is no snow present on the ground.

References:

 Liang, X., D. P. Lettenmaier, E. F. Wood, and S. J. Burges, A Simple hydrologically Based Model of Land Surface Water and Energy Fluxes for GSMs, J. Geophys. Res., 99(D7), 14,415-14,428, 1994.

Input Variables:

Variable

Type

Units

Description

 rec

int

N/A

Current record number

iveg

int

N/A

Current vegetation type

nlayer

int

N/A

Number of soil layers

Nveg

int

N/A

Total number of vegetation types in grid cell

snow

int

N/A

Flag for canopy_evap (TRUE = snow in canopy or snow on ground just melted, do not use canopy_evap, FALSE = use canopy_evap)

ice

double

mm/mm

Ice content of top layer

moist

double

mm/mm

Unfrozen moisture content of top layer

dp

double

m

Depth to thermal damping depth

surf_atten

double

fraction

Fractional attenuation of incoming radiation by vegetation cover

T0

double

C

Current surface temperature

T1

double *

C

Temperature at bottom of top layer

aero_resist

double

s/m

Aerodynamic resistance

Le

double

J/kg

Latent heat of vaporization

mu

double

fraction

Fraction of grid cell that receives precipitation

x

double *

fraction

Fraction of mu that receives precipitation greater than the inteception capacity of the vegetation

atmos

atmos_data_struct *

N/A
  • albedo - bare surface albedo [fraction]
  • rad - net surface radiation [W/m2]
  • shortwave - incoming shortwave radiation [W/m2]
  • longwave - incoming longwave radiation [W/m2]
  • air_temp - air temperature [C]
  • density - air density [kg/m3]

veg_var

veg_var_struct *

N/A
  • canopy_evap - evaporation from water stored in the canopy [mm]

energy

energy_bal_struct *

N/A
  • T[0] - previous time step surface temperature [C]
  • T[1] - previous time step temperature at bottom of top soil layer [C]
  • T[Tlayer-1] - average soil temperature at damping depth [C]
  • kappa - thermal conductivity of soil layer [W/m/K]
  • Cs - volumetric heat capacity of soil layer [W/m3/K]

gp

global_param_struct

N/A
  • dt - model time step [hrs]
  • Ulayer - number of thermal solution nodes above damping depth [N/A]
  • Llayer - number of thermal solution nodes below damping depth [N/A]

soil_con

soil_con_struct

N/A
  • depth - soil layer thickness [m]
  • max_moist - maximum soil layer moisture [mm]
  • bubble - bubbling pressure [cm]
  • expt - 2/Bp+3 where 3 is the pore-size distribution [N/A]

veg_class

int

N/A

Vegetation type class number

dmy

dmy_struct

N/A
  • month - current month

 

Output Variables:

Variable

Type

Units

Description

surf_temp

double

C

New surface temperature

layer

layer_data_struct *

N/A
  • evap - soil layer evapotranspiration [mm]

energy

energy_bal_struct *

N/A
  • grnd_flux - ground heat flux [W/m2]
  • latent - latent heat flux [W/m2]
  • sensible - sensible heat flux [W/m2]

 

Subroutines Called:

energy_bal_func.c

Modifications and Limitations:

 

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