1. Pacific Northwest Air Modeling Meetings 1 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Improvements to Surface Flux Computations in the MRF PBL Scheme, and Refinements to Urban Processes in the Noah LSM Model With the NCAR/ATEC Real-time FDDA and Forecast System Yubao Liu, Fei Chen, Tom Warner and Scott Swerdlin Research Applications Laboratory National Center for Atmospheric Research

2. Pacific Northwest Air Modeling Meetings 2 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu 1. MM5-based RTFDDA 2. A common problem in the MM5 PBL schemes 3. Modifications to the MRF PBL scheme 4. Refinements to the Noah LSM-urban 5. Results 6. Summary Outline

3. Pacific Northwest Air Modeling Meetings 3 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu WRF/MM5- FDDA Multi-scale DA and FCST Cold start t Forecast FDDA New 12 - 48 h forecast every 1 - 12 hrs, using all obs up to “now” TAMDAR MESONETs GOES Wind Prof Real-Time FDDA and Forecasting (RTFDDA) System All WMO/GTS Radars Etc. ACARS obs

4. Pacific Northwest Air Modeling Meetings 4 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu NCAR RTFDDA Applications 2002-SLC Olympics 2004-Athens Olympics 2006-Torino Olympics Joint Urban 2003, OKC Colorado wild fire Military operations Army test ranges Homeland security Wyoming cloud seeding FAA aviation weather Kauai island effect New York City 2005 Hurricanes TAMDAR appli. … 20+ Special Operation Sites 12 Regular Operational RTFDDA Systems

5. Pacific Northwest Air Modeling Meetings 5 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Continuing RTFDDA Modeling R&D:  Incorporate more new observations  Enhance data quality control  Refine data assimilation algorithms  Improve model physics schemes  Next-gen: ensemble DA and probabilistic forecasting: E-RTFDDA – (this afternoon)

6. Pacific Northwest Air Modeling Meetings 6 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Modifications to the MRF PBL Physics  Known problems with MM5 PBL schemes Underestimates day-time surface winds Overestimates PBL heights Vsfc from six PBL schemes ( Zhang and Zheng, 2003 ) MRF PBL OBS August 2002, 5 ranges, d3/d4 (MM5-RTFDDA operations)

7. Pacific Northwest Air Modeling Meetings 7 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu More realistic computation of thermally induced turbulence Alternative definition of PBL height by using local Ri More accurate surface heat-exchange formulation … a g 1 2 3 z i  Ri < Ric ? 1 2 3 Rib … Ribl … Modifications to the MRF PBL Physics

8. Pacific Northwest Air Modeling Meetings 8 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu  Results ( Case: May 27 – 28, 2003 ) Significant improve PBL developments and evolutions New OLD Comparison of Zi, simulated by the old and new PBL schemes with the ANL profiler measurement at Oxford, KS. RTFDDA Exp. Modifications to the MRF PBL Physics

9. Pacific Northwest Air Modeling Meetings 9 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu  Results ( Case: May 27 – 28, 2003 ) Correct day-time surface (10-m) wind biases Modifications to the MRF PBL Physics OLD f1012 OLD Final NEW final NEW f1012 BIAS (m/s) RMSE (m/s) GMT (hour)

10. Pacific Northwest Air Modeling Meetings 10 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu  Statistical Results 2002 (w/o mods) vs 2003 (with mods) RTFDDA operations over the Northeastern States Modifications to the MRF PBL Physics

11. Pacific Northwest Air Modeling Meetings 11 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Effects of urban canopy on PBL and airflow Refinements to Noah LSM Urban Physics Wake Mixing Drag Sunlit Urban surface:Dry, more-frictional and heat-trapped Intense shear at the top Shadow Heat trapped Solar radiation

12. Pacific Northwest Air Modeling Meetings 12 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Refinements to Noah LSM Urban Physics Modify the Noah-LSM urban physics parameters for urban bulk effect  Larger roughness length  turbulence generated by roughness elements  drag due to buildings  Smaller albedo  radiation trapping  Larger thermal capacity and conductivity  heat storage in substrate  Smaller water capacity

13. Pacific Northwest Air Modeling Meetings 13 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Five 2-way-nested Domains (45/15/4.5/1.5/0.5 km) D1 D2 D3,4,5 RTFDDA Operation During JU2003 (OKC)

14. Pacific Northwest Air Modeling Meetings 14 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Land use and water bodies on Domain 4 defined with USGS+MODIS data Aerial picture Domain 4,  X = 1.5 km RTFDDA Operation During JU2003 (OKC)

15. Pacific Northwest Air Modeling Meetings 15 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Average of eight clear-sky days in July 2003, at 06Z RTFDDA Operation During JU2003 (OKC) Surface sensible heat flux ( W/m 2 ) 2-m temperature and 10-m wind vectors

16. Pacific Northwest Air Modeling Meetings 16 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Case examples – Nocturnal PBL – 06Z June 24, 2003 PBL Height (m) A B A B URBAN Wind Speed (m/s; LLJ)  (km) 10 km RTFDDA Operation During JU2003 (OKC)

17. Pacific Northwest Air Modeling Meetings 17 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Case examples – Day-time PBL – 18Z July 5, 2003 W ( m / s )PBL Height ( m ) 37.0 A B AB 10 km  (km) URBAN RTFDDA Operation During JU2003 (OKC)

18. Pacific Northwest Air Modeling Meetings 18 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu JU2003: Mixing Layer Height Forecasts on Eight Good Weather Cases Color shade: Low-Power S/N ratio measurement from the ARL wind profiler Red and blue lines: RTFDDA forecast of Mixing Layer height at two OKC sites

19. Pacific Northwest Air Modeling Meetings 19 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu JU2003: Cases July 16 and July 24 P S M Urban Suburban Rural Comparison of Surface Temperature Diurnal Evolutions

20. Pacific Northwest Air Modeling Meetings 20 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Summary and Conclusions The surface flux and mixing-layer height computations in the widely-used MRF PBL scheme were modified. Simulation results show significant improvements in surface winds, and other variables as well. The Noah-LSM urban processes were refined to account for the basic properties of the urban canopy. Model results show encouraging simulations of urban heat-island, urban-induced meso-  scale circulations, and PBL development. Both mods have been incorporated into community MM5 and WRF models.  This work suggests  many research opportunities for mesoscale modeling, and  large improvements from even simple scheme “tune-up”

21. Pacific Northwest Air Modeling Meetings 21 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu JU2003 (OKC) RTFDDA URBAN SIMULATION Case examples – Day-time PBL – 18Z July 5, 2003  e (K) 37.0  ( K ) ABAB 10 km  (km) 37.0 A B URBAN

22. Pacific Northwest Air Modeling Meetings 22 NCAR/RAL - National Security Applications Program 22 – 25 October 2007 Seattle, WA yliu@ucar.edu Case examples – Day-time PBL – 18Z July 5, 2003 W ( m/s ) at p = 850 hPaT 2 ( C ) 37.0 T m =35.5C T o =35C RTFDDA Operation During JU2003 (OKC)