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