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Development of the Regional Arctic Climate System Model (RACM) ---
Department of Civil and Environmental Engineering University of Washington
Dec, 2009
Coupling WRF with the Variable Infiltration Capacity land model via a flux coupler
Modeling FrameworkGlobal Domain 4x5 resolution
runs: January 2001
Configuration WV (WRF/VIC)
Features specific to Cold-Land 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 Observation
Jan 2001
Feb 2001
Global WRF/VIC runs crash after about 4 month running with land surface becoming colder and colder
Surface skin T
Surface Air T
Second soil layer T
First soil layer T
Cold feedback???
Arctic Regional WRF/VIC runs --- Jan 5, 2001
Precipitation
Surface Air T
WRF/VIC Observation
Regional WRF/VIC runs crash after at 541 time step. After running 7~8 days, land surface temperature drops gradually irreversibly.
Surface Air T
Surface skin T
First soil layer T
Second soil layer T
Cold feedback???
Frozen soil scheme???
Arctic Regional WRF/VIC runs ---
Sensible Latent
Snow Depth Temperature
Jan 5, 2001
Sea Ice Free
Sea Ice Full
ControlSea ice area fraction is prescribed at
Sea Ice Free Sea Ice Full
AprMarFeb
Sea Ice Fraction prescribedJan 1, 2001
Experimental Design
Surface Temperature ---
Surface Air Temperature Surface Skin Temperature
WRF/VIC
Sea Ice Free
Sea Ice Full
Feb, 2001
WRF/VIC
Precipitation ---Feb, 2001
Sea Ice Free
Sea Ice Full
Precipitation Snow Depth
Latent Heat Sensible Heat
WRF/VIC
Sea Ice Free
Sea Ice Full
Feb, 2001
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)
Current issues ……
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 ;
Anomalously high sensible heat
(> 500 or < -500)
Anomalously high wind stress
Aerodynamic Resistance???
Anomalously low aerodynamic resistance (about 0.1) output from VIC 4.0.4 to WRF over some vegetation canopy
+ Instability
*sensible_heat = atmos_density*Cp*(Tair - (TMean))/ra;
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; }
Current solution in ……
• Sensible Heat ???
if( *HFLX < -500 ) { *HFLX = -500; }if( *HFLX > 500 ) { *HFLX = 500; }
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.
Future solution ---
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
VIC can use a finite difference solution that takes soil ice content into account. Cherkauer et al. (1999).
Soil Thermal Solution
allows for implicit solution allows for exponential node spacing
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
Ongoing work--- Updating the VIC4.0.4 in RACM to the newest released VIC4.1.1
Finished coding
Compiled successfully
Is testing and debugging …
Parrellizing VIC land model in CCSM system to improve computing performance.
Implement VIC routing model into RACM
Rout surface and subsurface
runoff into rivers
Future Work