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Enhancing Regional Climate Model Variability and Extremes: Strategies for Progress

Exploring current and future regional climate modeling advancements in solving variability and extreme climate challenges. Discusses validation issues, planned simulations, and the prototype development of CRCM 4.0. Examines variables and data for improved parameterization to enhance model accuracy.

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Enhancing Regional Climate Model Variability and Extremes: Strategies for Progress

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  1. Variability and Extremes in the CRCM Hélène Côté and Daniel Caya Climate Simulations Group Consortium Ouranos Development of Scenarios of Climate Variability and Extremes: Current Status and Next Steps Victoria, 16-17 October 2003

  2. Outline • Current status of CRCM • Policy Run II vs Policy Run III • Production runs with version 3.6.1 • Preliminary results (the first 5 years of the 25-year run) • Next operational version: CRCM 3.6.3 • Development of CRCM 4.0 • Variability issues in regional climate modelling • Modelling the extremes • The data we have • What we plan to do • Validation issues • How to improve the model

  3. From Policy Run II to Policy Run III 3.5.1 vs 3.6.1

  4. 45 km grid point spacing 193 x 145 grid points 29 vertical levels Lid: 30 km Archival : every 6 hours (pcp every timestep) Transient CO2 Spinup period: 2 years Approx. 1 month CPU time per simulated year …. 5.7Gb of model outputs per simulated month…. Current Simulations Configuration Topography (m) Policy Run II domain

  5. Current Simulations

  6. CO2 Equivalent Concentration • CRCM CGCM2, 1968 -1994, 2037-2063 IS92a CRCM

  7. CRCM/NCEP CRCM-CRU2 CRU2 Precipitation rate (mm/day)5-year mean: Summer CRU2: Climatic Research Unit TS 2.02 0.5°X 0.5° (Mitchell et al. 2003)

  8. CRCM/NCEP CRCM-CRU2 CRU2 Precipitation rate (mm/day)5-year mean: Winter

  9. CRCM/NCEP CRCM-CRU2 CRU2 Maximum Screen Temperature (ºC) 5-year mean: Summer

  10. CRCM/NCEP CRCM-CRU2 CRU2 Minimum Screen Temperature (ºC) 5-year mean: Summer

  11. CRCM Version 3.6.3 • Improve some biases of 3.6.1 related to the boundary layer: • Retun the control from the planetary waves • Too warm (Tmin) and too wet (pcp) Too much preciptation 1-layer bucket too deep and very wet Excessive cloud cover (Tmin too high) Too much evaporation

  12. Planned Simulations *We have to choose from CGCM2 simulations based on different CO2 emission scenarios. GCMx: A different GCM

  13. CRCM 4.0 • Prototype in development in collaboration with the CRCM Network (R.Laprise et al) • MC2 dynamics + GCMIII physics • Ed Chan MSC, Virginie Lorant CCCma • All CRCM physics and features need to be implemented • Prototype to be completed in early 2005

  14. Variability • Longer timeserie to assess variablity • 25 years simulations instead of 10 years • 2 compoments of the variability: • Intramonthly (seasonal) vs Interannual variability • Intramonthly variability: difficult to validate due to a lack of temporal resolution of gridded observed datasets • Results : Validation of interannual variability

  15. CRCM/NCEP CRCM-CRU2 CRU2 Precipitation Rate (mm/day)5-year Interannual Standard-DeviationWinter

  16. CRCM/NCEP CRCM-CRU2 CRU2 Maximum Screen Temperature 5-year Interannual Standard-Deviation Winter

  17. CRCM/NCEP CRCM-CRU2 CRU2 Minimum Screen Temperature 5-year Interannual Standard-Deviation Winter

  18. CRCM monthly extremes • Precipitations extremes : computed from precipitation archived every timestep (15 min) • Highest precipitation rate for different durations • Wet days for different thresholds • Dry days for different thresholds • Precipitation histogram • Daily extremes of specific humidity (screen) • Daily screen temperature extremes • Highest gusts at the lowest level of the model

  19. CRCM climate extremes(all in early stage of development) • Records of the simulation • Normals of the simulation • Climate indices (Stardex, etc…) • Precipitation histograms • Temperature distributions

  20. 5-year January Daily Precipitation Histogram nearest gridpoint vs station data: Victoria • From the 0.2 mm threashold • 124 / 155 rain days in CRCM • 3 events above 25 mm during the simulation • On average, • MSC obs: 17.8 / 31 (57%) rain days • CRCM : 24.8 / 31 (80%) rain days • Precipitation too frequent Total number of days Average number of days

  21. 5-year January Daily Precipitation Histogramnearest gridpoint vs station data: Kuujuaq • From the 0.2 mm threashold • 100 / 155 rain days in CRCM • 0 event above 25 mm during the simulation • On average, • MSC obs: 15.4 / 31 (49.6%) rain days • CRCM : 20.0 / 31 (64.5%) rain days • Precipitation too frequent [0.2-5[ Total number of days Average number of days

  22. Validation issues • Gridded climatologies • Lack of resolution • Lack of temporal resolution • Lack of variables • Lack of information about the topography (except CRU) • CRCM • Limited time-series • Grid point vs station data • Interpolation of datasets on the CRCM grid

  23. Improving regional climate models • Better representation of surface caracteristics • variables used by land surface scheme • Include smaller lakes • bathymetry, lake surface temperature, ice • from 1968-1999 • Better parameterisations • CRCM ensembles

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