Dr. Chris Kiley – NGC Dr. Jason Ching - ARL, NOAA, RTP CDR Stephanie Hamilton - DTRA

1. Initial Study of HPAC Modeled Dispersion Driven by MM5 With and Without Urban Canopy Parameterizations Dr. Chris Kiley – NGC Dr. Jason Ching - ARL, NOAA, RTP CDR Stephanie Hamilton - DTRA

3. Outline of Presentation • Overview of HPAC • Objective of Study • Preliminary Results • Next Steps

4. DTRA • Defense Threat Reduction Agency • Mission is to safeguard the USA (and its allies) from weapons of mass destruction (WMD) (chemical, biological, radiological, nuclear, and high yield explosives) by providing capabilities to reduce, eliminate, or counter such threats and mitigate its effects. • DTRA’s Hazard Prediction and Assessment Capability (HPAC) • Automated software system provides the means to accurately predict the effects of hazardous material releases into the atmosphere and its impact on civilian and military populations. • The system models hazard areas produced by military or terrorist incidents and industrial accidents using: • integrated source terms • high-resolution weather forecasts • particulate transport analyses

5. Weather and Environment Data Input Process for HPAC Source Data Land Cover (Landscan) Interpolation to Uniform Grid Transport & Dispersion Concentration in space and time Terrain Data (Landscan) Weather Data (Many sources) Calculate Mass- Consistent Wind Field

6. Meteorological Input Considerations • Primary influence on Atmospheric Transport and Dispersion (ATD) • Compatible spatial resolution for the venue of the hazardous release • Operational: Rapid calculations • Is it Urban? This is the “Problem” we are to address.

7. Model Resolution Coarser resolution (5 km) reveals little detail in the wind field Higher resolution (1.67 km) reveals additional wind field structure

8. Urban AT&D • Urban environment greatly affects local meteorology • Wind velocity and direction • Turbulence profiles • Thermal characteristics • NWP models not well suited to simulate urban areas • Grid resolutions, detailed building information, parameterization, operational timeliness of forecasts, etc.

9. Urban AT&D • Urban meteorology and AT&D is a current area of focused R&D • Not well understood yet highest probability of terrorist attack • NWP does not currently handle urban areas well • AT&D systems include simplified assumptions that describe the influence of urban environment • Mass consistent adjustments to underlying building topography • CFD solutions as computational capabilities advance • Coupled CFD/NWP models • Urban dispersion models

10. UDM and other approaches • Urban Dispersion Model (UDM) • Dstl (UK) • Operationally Fast • Current Urban Capability within HPAC

11. Urban Dispersion Model (UDM)

12. UWM Winds @ 50m Height Yellow arrows show wind speed and direction At 50 m above the ground, the flow is from the north or north-northeast at a steady speed

13. UWM Winds @ 7m Height At 7 m above the ground, the flow is channeled around Capitol Hill and down the Mall, with strong winds Weaker winds in built-up parts of the city

14. Study Description HPAC now driven by modeled meteorology (MM5): Sensitivity study to grid size and to urbanization with Reynolds Averaging vs detailed Urban Canopy Parameterization versions.Preliminary results for Houston include: • 4 km MM5 • 4 km MM5 with UDM • 1 km MM5 • 1 km MM5 with UDM • 1 km MM5 Urban Canopy Model • Date: August 29, 2000 • Time of Release: 0700 EDT • Duration of release: 4 hours

15. Houston Case Study • 12 UTC (7 AM) 29 August 2000 • GB Release, location arbitrarily chosen

16. 4 km

17. 4 km with UDM

18. 1 km

19. 1 km with UDM

20. 1 km Urbanized MM5

21. Status of Study, Preliminary Findings & Caveats • Successfully linked urbanized MM5 with HPAC. • Only limited results performed at this time • UDM appears to slow spread as expected • Relative reduction in agent spread due to enhanced grid resolution not evident for early morning release • Urbanized MM5 comparative reduction in spread also not pronounced at 0700 • Results pending for different time of day release times

22. Future investigations continues to: • Examine and understand sensitivity to different times of release, different release locations and different duration of puff travel in order to appreciate differences in flow and turbulence fields due to grid size and urban descriptions. • Understand mesoscale modeling abilities to simulate effect of urbanization on land-lake/sea breeze, boundary layer and heat island structures on HPAC simulations. • Develop operational (fast) and R&D versions.

23. The End Thank you for your attention Disclaimer:The research presented here was performed under the Memorandum of Understanding between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) and under agreement number DW13921548. This work constitutes a contribution to the NOAA Air Quality Program. Although it has been reviewed by EPA and NOAA and approved for publication, it does not necessarily reflect their policies or views.