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November 1, 2013

November 1, 2013. 3SAQS WRF Modeling Recommendations. Bart Brashers, ENVIRON Jared Heath Bowden, UNC. Where We Left Off at the Last Meeting. Week long simulations for beginning of January and July Tests included: ECMWF vs. NAM Initial and Boundary Conditions USGS vs. NLCD land-use datasets

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November 1, 2013

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  1. November 1, 2013 3SAQS WRF Modeling Recommendations Bart Brashers, ENVIRON Jared Heath Bowden, UNC

  2. Where We Left Off at the Last Meeting • Week long simulations for beginning of January and July • Tests included: • ECMWF vs. NAM Initial and Boundary Conditions • USGS vs. NLCD land-use datasets • PX vs. NOAH land-surface model • TOPO option • Reduced vertical levels

  3. Initial Conclusions from Last Meeting • Our conclusions from model metrics (T,Q,WS,WD) • Keep NAM instead of ECMWF • NLCD with NOAH requires more development • TOPO option created larger negative wind speed bias • Do not reduce number of vertical levels, especially given the desire to model temperature inversions • PX LSM/ACM2 vs. NOAH/YSU – found that PX crashed for January; preliminary comparison for July indicated PX was also comparable to our BASE configuration

  4. Where We Went: Several Blind Alleys • PX LSM/ACM2 would run with 27 levels, crash consistently with 37 levels • wrfhelp and Jon Pleim consulted • Coding error caused crash instead of graceful stop • Nudging with MESONET data (part of MADIS) caused some runs to crash (segmentation fault) • Could not find bad observation • Did not improve WRF performance noticeably • New “snow” data from Polar WRF turned out to be only over ice, not over land • Good for them, but not for us

  5. Revised “Base Case” • Do not use objectively analyzed fields (metoa files created by OBSGRID.EXE) for any domains • NAM already analyzed at 12km (c.f. 36 & 12km domains) • 4km domain has no analysis nudging, so uses metoa file only for initial conditions, which should have no effect after spin-up • Using metoa files produced far to much precipitation in previous ENVIRON work near Four Corners • Use OBS nudging every hour • Was set to every 3 hours • Retain nudging coef’s used in ENVIRON Four Corners WRF

  6. PRISM Precipitation Comparison • PRISM is gridded observational data • Sophisticated interpolation techniques • 4km resolution, monthly total precip • PRISM data is interpolated to each WRF nested grid • WRF output is simply summed

  7. WRF Base Case vs. PRISM, January 2011 WRF PRISM

  8. WRF Base Case vs. PRISM, July 2011 WRF PRISM

  9. WRF Base Case vs. PRISM, January 2011 WRF PRISM

  10. WRF Base Case vs. PRISM, July 2011 WRF PRISM

  11. Preliminary Conclusion Base Case precipitation performance is acceptable. Let’s look at the rest of the typical performance metrics (METSTAT).

  12. Introduction to Soccerplots • Plots of model Bias vs. Error for each month • Performance envelopes from survey of many MM5 and WRF runs BIAS ERROR • How many months score a goal? GOOOOAAALLL!

  13. BASE EPA

  14. BASE EPA

  15. BASE EPA

  16. BASE EPA

  17. Preliminary Conclusion We’re doing about as well as EPA’s WRF modeling, which they use for CMAQ. But can we do better with stronger nudging?

  18. Nudging Case • New test case, following Kristi Gebhart/RoMANS II • Analysis (3D) nudging the same as Base case • OBS nudging on 4km domain stronger • Nudge Winds and Temperature, but not Humidity • Winds nudging coefficient = 1.2E-3 • Temperature nudging coefficient = 6.0E-4 • Radius of influence = 60km • Do not nudge to ACARS, SatWind, or Profiler data

  19. Preliminary Conclusion Stronger nudging reduces model error. At least when you verify using the same data you used for nudging...

  20. Verifying Against MESONET Data • MADIS data contains many “data streams” • ACARS Aircraft No thanks • HDW Satellite winds No thanks • MARITIME Ship reports Not relevant for 4km • METAR ASOS, AWOS, more. Yes please! • RAOB Radiosondes Not relevant for SFC • SAO Canadian stations Not relevant for 4km • MESONET Smaller station Interesting… • Could we nudge with METAR & RAOB, and verify against MESONET data?

  21. 4 WRF Runs vs. 3 Verification Sets

  22. 4 WRF Runs vs. 3 Verification Sets

  23. 4 WRF Runs vs. 3 Verification Sets

  24. 4 WRF Runs vs. 3 Verification Sets

  25. Preliminary Conclusion Stronger nudging did not change model performance, when using independent verification data (MESONET). Precip?

  26. Base Case vs. Nudging Case, July 2011 Inches Base Case Nudging Case

  27. New Case: No Temperature Nudging Base Case No Temp Nudging

  28. Preliminary Conclusion OBS nudging too strongly produces too much precipitation, without changing performance vs. independent data.

  29. ENVIRON/UNC WRF Recommendations • Taken from Base Case • 37 Vertical Levels • NOAH LSM • YSU PBL • RRTMG shortwave & longwave radiation • Thompson Moist Physics • KF Cumulus on 36 & 12km • kfeta_trigger = 2 • No shallow Cu (not tied to deep convection) • Light OBS nudging of Winds, Temp, and Humidity

  30. Thanks for listening! Questions? Discussion? Bart Brashers bbrashers@environcorp.com Jared Heath Bowden jhbowden@email.unc.edu

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