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 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)

Validation of coupled WRF/VIC modeling system WRF/VIC Precipitation Jan 2001 Feb 2001 Observation

Validation of coupled WRF/VIC modeling system WRF/VICObservation 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/VICObservation

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 --- SensibleLatent Snow Depth Temperature Jan 5, 2001

Sea Ice Free Sea Ice Full Control Sea ice area fraction is prescribed at Sea Ice Free Sea Ice Full AprMarFeb Sea Ice Fraction prescribed Jan 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 PrecipitationSnow Depth

Latent HeatSensible 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) 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 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 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 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