1 / 28

Science Question 3: Numerical Weather Prediction Aspects of Forecasting Alberta Thunderstorms

Science Question 3: Numerical Weather Prediction Aspects of Forecasting Alberta Thunderstorms. Jason Milbrandt Recherche en Prévision Numérique [RPN] (Numerical Weather Prediction Research Section), Meteorological Research Division, Environment Canada. OUTLINE of PRESENTATION

creola
Download Presentation

Science Question 3: Numerical Weather Prediction Aspects of Forecasting Alberta Thunderstorms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Science Question 3:Numerical Weather Prediction Aspects of Forecasting Alberta Thunderstorms Jason Milbrandt Recherche en Prévision Numérique [RPN] (Numerical Weather Prediction Research Section), Meteorological Research Division, Environment Canada 1st UNSTABLE Science Workshop 18-19 April 2007

  2. OUTLINE of PRESENTATION • ISSUES related to high-resolution NWP • DEMONSTRATION of high-resolution simulations • SUB-QUESTIONS • CONCLUSION 1st UNSTABLE Science Workshop 18-19 April 2007

  3. Science Question 3 • Premise: • NWP part of UNSTABLE should focus on maximizing and improving the usefulness of high-resolution Canadian models as forecasting tools for severe convection • (with emphasis on storms that originate along the foothills)

  4. Science Question 3 Science Question 3: To what extent can high-resolution NWP models contribute to forecasting the initiation and development of severe convective storms that originate in the Alberta foothills? • That is: • How can the usefulness of the current GEM-LAM (2.5 km) forecasts be maximized? • How can the forecasts from the GEM-LAM be improved?

  5. ISSUES Pertaining to Science Question 3

  6. Science Question 3 • Issues Pertaining to Science Question 3: • (and high-resolution NWP in general) • DATA • - initial conditions of model are crucial • high-resolution data assimilation is a complex topic • research on development of high-resolution analyses is possible in context of UNSTABLE • - IOP data useful for verification (examination of sub-questions)

  7. Science Question 3 • Issues Pertaining to Science Question 3: • (and high-resolution NWP in general) • DATA • COMPUTATIONAL RESOURCES • high-resolution NWP is very expensive • resources are increasing •  This is a logical time to examine Science Question 3

  8. Science Question 3 • Issues Pertaining to Science Question 3: • (and high-resolution NWP in general) • DATA • COMPUTATIONAL RESOURCES • MODEL DETAILS • GEM is an appropriate tool for this job • non-hydrostatic, limited-area model (LAM), sophisticated physics • To be learned: • 1. modelling strategies • 2. improvements to physics parameterizations

  9. Science Question 3 • Issues Pertaining to Science Question 3: • (and high-resolution NWP in general) • DATA • COMPUTATIONAL RESOURCES • MODEL DETAILS • DETERMINISTIC vs. PROBABILISTIC • Use of any single model run is inherently deterministic • Analysis errors mean that a single high-resolution NWP run is doomed •  Ensembles of runs will ultimately need to be considered for high-resolution NWP

  10. EXAMPLES of simulated thunderstorms

  11. RADAR 14 July 2000 Pine Lake Storm Accumulated Precipitation Estimated from WMI radar: 4-km GEM simulation:* * Source: Erfani et al. (2003), Meteorol. Atmos. Phy.

  12. mm 40 30 25 20 16 13 10 8 6 4 50 km RADAR mm 30 25 20 15 10 5 50 km 14 July 2000 Pine Lake Storm Accumulated Precipitation Estimated from WMI radar: N 8:00 pm 1-km MC2 simulation:* N 8:00 pm 33 mm 1-km CNTR * Source: Milbrandt and Yau (2006a), J. Atmos. Sci.

  13. 16 km 16 km 40 km 40 km 750 hPa COMPOSITE Maximum: 63.6 dBZ Maximum: 60–65 dBZ dBZ 1-km MC2 Simulation* using detailed microphysics SIMULATION: 4:30 h [6:30 pm] RADAR: 0030 UTC [6:30 pm] dBZ 65 60 57 54 51 48 45 42 39 36 33 30 N N * Source: Milbrandt and Yau (2006a), J. Atmos. Sci.

  14. Equivalent Reflectivity (750 hPa) Reflectivity CAPPI (2 km) N 10 km 10 km 1-km MC2 Simulation* using detailed microphysics 1-km SIMULATION: 4:15 h [6:15 pm] RADAR: 0030 UTC [6:30 pm] N Source: Milbrandt and Yau (2006a), J. Atmos. Sci.

  15. SENSITIVITY EXPERIMENTS:Variations in microphysics scheme 700 hPa: Zeh[dBZ] Local time: 6:30 pm (Simulation time: 4:30 h) TRIPLE-MOMENT DOUBLE-MOMENT Diagnosed a SINGLE-MOMENT-A DOUBLE-MOMENT Fixed a = 0 Source: Milbrandt and Yau (2006b), J. Atmos. Sci.

  16. 35 14 25 13 23 34 SENSITIVITY EXPERIMENTS:Variations in microphysics scheme 6-h ACCUMLATED SOLID PRECIPITATION (Hail)[mm] TRIPLE-MOMENT DOUBLE-MOMENT Diagnosed a 9 9 10 SINGLE-MOMENT DOUBLE-MOMENT Fixed a = 0 Source: Milbrandt and Yau (2006b), J. Atmos. Sci.

  17. SENSITIVITY OF MICROPHYSICS SCHEME 4-category SINGLE-momentvs. 6-cateogory DOUBLE-moment: MC2_2.5 km: Kong-Yauscheme (nested from GEM15 output) “GRAUPEL” 429 mm h-1 RAIN [g kg-1] MC2_2.5 km: Milbrandt-Yauscheme (nested from GEM15 output) GRAUPEL HAIL 112 mm h-1 RAIN [g kg-1]

  18. SUB-QUESTIONS for Science Question 3

  19. Science Question 3 SUB-QUESTION A: What defines a “success” for a high-resolution simulation in terms providing useful numerical guidance from the current GEM-LAM-2.5 configuration? • The simulated storm structure may be realistic, but its track displaced; • The location of CI may be incorrect, but the type of storm that is forecast may be similar to the observed •  Success or a bust?

  20. Science Question 3 SUB-QUESTION B: How can the model’s ability to accurately simulate the general nature of the observed convection be quantified? • Once a “success” is defined, how can the general skill of the model be measured? • Important for evaluating the effects of changes to the model configuration

  21. Science Question 3 SUB-QUESTION C: Can the atmospheric state be classified a priorias “predictable” or “non-predictable” in terms of recommended use of the GEM-LAM-2.5 run to guide the forecast?

  22. Science Question 3 SUB-QUESTION D: How realistic are the simulated storm structures and microphysical fields? • Comparison to radar observations • (related to definition of “success”?)

  23. Science Question 3 SUB-QUESTION E: How realistic is the evolution of the boundary layer and surface processes in the foothill regions for the high-resolution model simulations? • Comparison to IOP observations • Sensitivity tests for hind-cast simulations

  24. Science Question 3 SUB-QUESTION F: Can deficiencies in the current physical parameterizations be identified? • Comparison to IOP observations • Sensitivity tests for hind-cast simulations

  25. Science Question 3 SUB-QUESTION G: What would be the effect of performing a subsequent nest to a higher-resolution (e.g. 1-km) grid, driven from the 2.5-km run? • dx = 2.5 km is INSUFFICIENT to fully resolve individual storms • Would the value added by a 1-km grid be worth the cost?

  26. Science Question 3 SUB-QUESTION H: Can an ensemble of high-resolution runs improve the prediction of convective initiation? • Modified ICs (different members from different 15-km driving runs) • Modified physical parameterizations/settings for 2-5 km runs

  27. Science Question 3 SUB-QUESTION I: Can a high-resolution analysis, created using the additional observations, improve the numerical prediction of convective initiation and subsequent storm development?

  28. CONCLUSION • Emphasis of NWP component of UNSTABLE is on maximizing and improving the utility of high-resolution NWP output as a forecast tool • Real-time 2.5-km runs will be done (and archived) by CMC for summers of 2007 and 2008 (and hopefully beyond…) • Investigation of several sub-questions can begin any time 1st UNSTABLE Science Workshop 18-19 April 2007

More Related