unifhycontrib.artemis
- class unifhycontrib.artemis.SurfaceLayerComponent
Artemis provides a simple runoff production model designed to be comparable with the runoff-production models typically embedded within climate models.
It is driven with precipitation, radiation, temperature, humidity and wind speed on a daily time step and calculates canopy interception, evaporation, snowmelt, infiltration, and runoff. It uses a Rutter–Gash canopy formulation (Gash, 1979) to represent interception, together with Penman–Monteith evaporation calculated using available radiation data (Monteith, 1965). Soil moisture is accounted for using a two-layer model with saturation-excess runoff computed using a generalized TOPMODEL (Clark and Gedney, 2008). The snowpack is represented using a temperature-based model of accumulation and melt (Moore et al., 1999, Hock, 2003, Beven, 2011). Snow accumulates when precipitation falls while temperature is below a threshold temperature. When temperature is above a threshold for melt, melting occurs at a rate proportional to the difference between the current temperature and the melting temperature. This conceptual model is widely used (Hock, 2003, Zhang et al., 2006, Rango and Martinec, 1995, Beven, 2011) and gives performance comparable with that of more parameter rich energy balance models, despite their greater complexity (Parajka et al., 2010).
The surface layer component of Artemis comprises canopy interception, evaporation, and snowmelt.
- Contributors
Simon Dadson [1,2]
- Affiliations
UK Centre for Ecology and Hydrology
School of Geography and the Environment, University of Oxford
- Licence
BSD-3
- Copyright
2020, University of Oxford
- Codebase
Inputs
- name
precipitation_flux
- units
kg m-2 s-1
- kind
dynamic
- name
specific_humidity
- units
1
- kind
dynamic
- name
surface_downwelling_shortwave_flux_in_air
- units
W m-2
- kind
dynamic
- name
surface_downwelling_longwave_flux_in_air
- units
W m-2
- kind
dynamic
- name
air_temperature
- units
K
- kind
dynamic
- name
surface_albedo
- units
1
- kind
static
- name
wind_speed
- units
m s-1
- kind
dynamic
- name
vegetation_height
- units
m
- kind
static
- name
leaf_area_index
- units
1
- kind
climatologic
- frequency
monthly
Outputs
- name
water_evaporation_flux_from_canopy
- description
evaporation of the water on the leaf surface
- units
kg m-2 s-1
Outwards
- name
canopy_liquid_throughfall_and_snow_melt_flux
- units
kg m-2 s-1
- to
subsurface
- method
mean
- name
transpiration_flux_from_root_uptake
- units
kg m-2 s-1
- to
subsurface
- method
mean
Constants
- name
sigma_sb
- description
Stefan-Boltzman constant
- units
W m-2 K-4
- default_value
5.67e-08
- name
kappa
- description
von Karman constant
- units
1
- default_value
4.1e-01
- name
lambda_lh
- description
latent heat of vaporisation (water vapour @ 288K) - M&U90 p.268
- units
J kg-1
- default_value
2.48e+06
- name
rho_a
- description
specific mass of (dry) air @ 288K - M&U90 p.268
- units
kg m-3
- default_value
1.22e+00
- name
rho_lw
- description
specific mass of liquid water
- units
kg m-3
- default_value
1.0e+03
- name
c_p
- description
specific heat of air - M&U90 p.267
- units
J kg-1 K-1
- default_value
1.01e+03
- name
R_v
- description
gas constant for water vapour - P&P77 p.23
- units
J kg-1 K-1
- default_value
4.615e+02
- name
t_freeze
- description
freezing point of water
- units
K
- default_value
2.73e+02
- name
gamma
- description
psychrometric constant [kPa/K] M&U90 p.181
- units
kPa K-1
- default_value
6.6e-02
- name
D_s
- description
drainage rate when canopy is full - Shuttleworth, 2007. p. 218; orig Rutter
- units
m s-1
- default_value
6.0e-09
- name
b
- description
canopy drainage decay term - Shuttleworth, 2007. p. 218
- units
s-1
- default_value
6.2e-02
- name
F
- description
degree-day melting factor - Beven 2000; 0.004 m/K/day
- units
m K-1 s-1
- default_value
4.6e-08
- name
z
- description
height measurement for wind speed
- units
m
- default_value
1.0e+01
States
- name
canopy_store
- units
m
- name
snowpack_store
- units
m
SpaceDomain Properties
- name
land_sea_mask
- required
False
- name
flow_direction
- required
False
- name
cell_area
- required
False