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Dynamical downscaling of ERA-40 with WRF in complex terrain in Norway – comparison with ENSEMBLES

WWW.BJERKNES.UIB.NO. Dynamical downscaling of ERA-40 with WRF in complex terrain in Norway – comparison with ENSEMBLES. U. Heikkilä, A. D. Sandvik and A. Sorteberg. Wetter Dryer. Dryer. Motivation. Expected change in rainfall (SRES A1B). Bergen. 2007. 2005. 1993. 1992.

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Dynamical downscaling of ERA-40 with WRF in complex terrain in Norway – comparison with ENSEMBLES

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  1. WWW.BJERKNES.UIB.NO Dynamical downscaling of ERA-40 with WRF in complex terrain in Norway – comparison with ENSEMBLES U. Heikkilä, A. D. Sandvik and A. Sorteberg

  2. WetterDryer Dryer Motivation Expected change in rainfall(SRES A1B) Bergen

  3. 2007 2005 1993 1992 Nov 2004 - Jan 2005: 1387.8 mm Nov 2006 – Jan 2007: 1397.7 mm Motivation: precipitation on Norwegian west coast November – Januar 1890 - 2008

  4. More extremes observed

  5. ERA-40 (1.1 deg.) WRF to 30 km and 10 km – nudged and free Arpege GCM (appr. 50 km) - nudged and free WRF to 30 km and 10 km – nudged and free Control run: 1961-1990 Evaluation against surface parameters of Norwegian met. office “Comparison” with 12 RCM’s from ENSEMBLES project High-resolution climatology in Norway

  6. Domain: 30 km – 10 km

  7. Very large outer domain to increase RCM independency 30 km / 10 km / 40 vertical levels to 50 hPa Default microphysics, PBL schemes Noah land-surface, CAM radiation 1-way nesting Spectral nudging in outer domain waves -> 1000 km no nudging in PBL weak nudging (every 24 hrs) of u,v,gph no nudging of humidity Details

  8. Results – precipitationERA40 – WRF nudged Bias of 30-year mean daily precipitation (%)

  9. Results - precipitation

  10. Results – precipitationERA40 – WRF nudged 0.95 0.99 0.8 0.6 0.9 0.7 0.025-0.5

  11. Results – 2m temperatureERA40 – WRF nudged

  12. Results – 2m temperatureERA40 – WRF nudged

  13. Results - overview

  14. Sensitivity to nudging - precipitation NUDGED FREE

  15. Sensitivity to nudging - precipitation ERA-40 Arpege N to ERA40

  16. WRF reproduces observed climate 1961-1990 reasonably well 10 km resolution improves precipitation, surface temperature and winds extremes better represented High resolved North Atlantic advantageous for Norwegian (European) west coast: phase of precipitation events improved temperature bias significantly reduced, especially between regions spectral nudging essential to keep low pressure systems consistent with driving data What about forcing with GCM data? Summary

  17. Results – 2m temperature

  18. Results - Extreme precipitation

  19. Results - Extreme temperature

  20. Results – 10m wind coast only

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