Development of the Regional Arctic Climate System Model (RACM) ---

1
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
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Modeling Framework
Global 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)

3
Validation of coupled WRF/VIC modeling system
WRF/VIC
Observation
Jan 2001
Feb 2001
Precipitation
Precipitation
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Validation of coupled WRF/VIC modeling system
WRF/VIC
Observation
Jan 2001
Feb 2001
5
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
6
Arctic Regional WRF/VIC runs ---
Jan 5, 2001
WRF/VIC
Observation
Precipitation
Surface Air T
7
Regional WRF/VIC runs crash after at 541 time
step. After running 78 days, land surface
temperature drops gradually irreversibly.
Surface skin T
Cold feedback???
Surface Air T
First soil layer T
Second soil layer T
Frozen soil scheme???
8
Arctic Regional WRF/VIC runs ---
Jan 5, 2001
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Experimental Design
Control
Sea ice area fraction is prescribed at
Sea Ice Full
Sea Ice Free
Sea Ice Free
Jan 1, 2001
Sea Ice Fraction prescribed
Sea Ice Full
Apr
Mar
Feb
10
Surface Temperature ---
Feb, 2001
Surface Air Temperature
Surface Skin Temperature
WRF/VIC
Sea Ice Free
Sea Ice Full
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Precipitation ---
Feb, 2001
Precipitation
Snow Depth
WRF/VIC
Sea Ice Free
Sea Ice Full
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Feb, 2001
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Albedo ???
Current issues

• ? Currently VIC output one albedo value to four
  albedos required by WRF.
• clm_l2aalbd(g,1)
• clm_l2aalbd(g,2) out_data -gtalbedo
• clm_l2aalbd(g,2)
• clm_l2aalbd(g,2)

Wind Stress ???
VIC calculates wind stress according the equation
in CLM clm_l2ataux forc_rho forc_u /
out_data-gtaero_resist clm_l2atauy forc_rho
forc_v / out_data-gtaero_resist
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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 (gt 500 or lt
-500)
Instability

sensible_heat atmos_densityCp(Tair -
(TMean))/ra
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wrf_vic_interface.c
Current solution in

• Aerodynamic Resistance???
• if( out_data-gtaero_resist lt 1 )
• resist out_data-gtaero_resist 100
• out_data-gtaero_resist resist
• if( out_data-gtaero_resist lt 10
  out_data-gtaero_resist gt1 )
• resist out_data-gtaero_resist 10
• out_data-gtaero_resist resist

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.

• Sensible Heat ???

if( HFLX lt -500 ) HFLX -500 if(
HFLX gt 500 ) HFLX 500
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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                               
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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
?
?
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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