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

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

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  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

  2. 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

  4. 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 7~8 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. Jan 5, 2001 Snow Depth Temperature Latent Sensible Arctic Regional WRF/VIC runs ---

  9. 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 Feb Mar Apr

  10. Surface Temperature --- Feb, 2001 Surface Air Temperature Surface Skin Temperature WRF/VIC Sea Ice Free Sea Ice Full

  11. Feb, 2001 Precipitation --- Precipitation Snow Depth WRF/VIC Sea Ice Free Sea Ice Full

  12. Latent Heat Sensible Heat WRF/VIC Sea Ice Free Sea Ice Full Feb, 2001

  13. 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 ;

  14. Aerodynamic Resistance??? Anomalouslylow 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;

  15. 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; } 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 < -500 ) { *HFLX = -500; } if( *HFLX > 500 ) { *HFLX = 500; }

  16. 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

  17. 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 ●

  18. 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

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