Development of the Regional Arctic Climate
System Model (RACM) ---
Coupling WRF with the Variable Infiltration Capacity
land model via a flux coupler
Department of Civil and Environmental Engineering
University of Washington
Dec, 2009
Modeling Framework
Global Domain 4x5 resolution
runs: January 2001
Configuration WV (WRF/VIC)
Features specific to ColdLand Processes:
• Two-layer energy balance
snow model (Storck et al. 1999)
• Frozen soil/permafrost
algorithm (Cherkauer et al.
1999, 2003)
• Lakes and wetlands model
(Bowling et al. 2004)
•Blowing snow algorithm
(Bowling et al. 2004)
Validation of coupled WRF/VIC modeling system
WRF/VIC
Jan 2001
Feb 2001
Observation
Validation of coupled WRF/VIC modeling system
WRF/VIC
Jan 2001
Feb 2001
Observation
Global WRF/VIC runs crash
after about 4 month running
with land surface becoming
colder and colder
Cold feedback???
Surface skin T
Surface Air T
First soil layer T
Second soil layer T
Arctic Regional WRF/VIC runs --Jan 5, 2001
WRF/VIC
Precipitation
Surface Air T
Observation
Regional WRF/VIC
runs crash after at 541
time step. After
running 7~8 days, land
surface temperature
drops gradually
irreversibly.
Surface skin T
Cold feedback???
Surface Air T
Second soil layer T
Frozen soil scheme???
First soil layer T
Arctic Regional WRF/VIC runs --Snow Depth
Latent
Temperature
Sensible
Jan 5, 2001
Experimental Design
Sea ice area fraction is prescribed at
Sea Ice Free
Control
Sea Ice Full
Sea Ice Free
Jan 1, 2001
Sea Ice Fraction prescribed
Feb
Mar
Apr
Sea Ice Full
Surface Temperature --Surface Air Temperature
WRF/VIC
Sea Ice Free
Sea Ice Full
Feb, 2001
Surface Skin Temperature
Feb, 2001
Precipitation --Precipitation
WRF/VIC
Sea Ice Free
Sea Ice Full
Snow Depth
Feb, 2001
Latent Heat
WRF/VIC
Sea Ice Free
Sea Ice Full
Sensible Heat
Current issues ……
Albedo ???
● Currently VIC output one albedo
value to four albedos required by WRF.
clm_l2a%albd(g,1)
clm_l2a%albd(g,2) = out_data ->albedo
clm_l2a%albd(g,2)
clm_l2a%albd(g,2)
Wind Stress ???
VIC calculates wind stress according the equation in CLM:
clm_l2a%taux = forc_rho * forc_u / out_data->aero_resist ;
clm_l2a%tauy = forc_rho * forc_v / out_data->aero_resist ;
Aerodynamic Resistance???
Anomalously low aerodynamic
resistance (about 0.1) output from
VIC 4.0.4 to WRF over some
vegetation canopy
Anomalously high
wind stress
+
Anomalously high
sensible heat
(> 500 or < -500)
Instability
*sensible_heat = atmos_density*Cp*(Tair - (TMean))/ra;
Current solution in ……
wrf_vic_interface.c
• Aerodynamic Resistance???
if( out_data->aero_resist < 1 ){
resist = out_data->aero_resist * 100;
out_data->aero_resist = resist;
}
if( out_data->aero_resist < 10 && out_data>aero_resist >1 ) {
resist = out_data->aero_resist * 10;
out_data->aero_resist = resist;
}
• Sensible Heat ???
if( *HFLX < -500 ) { *HFLX = -500; }
if( *HFLX > 500 ) { *HFLX = 500; }
Future solution --The newest released VIC4.1.1
● Modified to reporting the grid cell
average aerodynamic resistance
● Control how aerodynamic resistances is
used to calculate sensible and latent heat
in snow-filled canopy.
Ongoing work--Updating the VIC4.0.4 in RACM to the newest released VIC4.1.1
New features in VIC4.1.1
Snow Model
●spatially-distributed (laterally) snow coverage
● blowing snow sublimation
Dynamic Lake/Wetland Model
•Multi-layer lake model of Hostetler et al. 2000
•Energy balance model
•Mixing, radiation attenuation, variable ice cover
•Dynamic lake area (taken from topography)
allows seasonal inundation of adjacent wetlands
•Currently not a part of channel network
Frozen Soil Formulation
Soil Thermal Solution
VIC can use a finite difference solution
that takes soil ice content into account.
Cherkauer et al. (1999).
Permafrost Enhancements
Excess Ice and Subsidence
Model
Excess ice is the concentration of
ice in excess of what the soil can
hold were it unfrozen
Models the melting of excess ice in
a soil layer that causes the ground
to subside
● allows for implicit solution
● allows for exponential node spacing
Ongoing work--Updating the VIC4.0.4 in RACM to the newest released VIC4.1.1
Finished coding
Compiled successfully
Is testing and debugging …
Future Work
Parrellizing VIC land model in CCSM system
to improve computing performance.
Implement VIC routing model into RACM
Rout surface and subsurface
runoff into rivers