1. Intro to Modeling – Terms & concepts Marti Blad, Ph.D., P.E. ITEP 5.29.13

2. AP models vary in complexity Mathematically simulate environmental processes to predict pollution movement and concentrations – More than one way to describe w #’s Physical, Chemical and Biological World Solar radiation is energy or process driver – The Sun

3. The Sun’s impact on Earth’s surface

4. AP Physical Scale Determine Limitations & Assumptions – Scale = size of area modeled – Resolution = level of detail – Other Physical processes; meteorology, source types – Topography; urban vs rural, water bodies, mountains – Detail for Inputs and outputs of model ModelDomain ScaleResolution Microscale200m x 200mx 100 m5 m Mesoscale (urban)100Km x 100Km x 5Km2 Km Regional1000Km x 1000Km x 10Km20 Km Synoptic (continental)3000Km x 3000Km x 20Km80 Km Global65000Km x65000Km x20Km

6. AP Model Time periods Long term or short term temporal period Affects resolution (spatial detail) – Data input and data output – Minutes vs hours vs days Physical processes match time scales – Atmospheric temperature profiles Chemical reactions affected by solar intensity – Changes every second! Emission source rates continuous or changing – Equilibrium or steady state

7. Large Scale Advection: Movement with bulk flow (wind)

8. Small Scale Diffusion: Molecular mixing because of concentration differences. High concentration moves to lower concentration

9. Where large and small meet Dispersion: Total plume spread caused by three dimensional advection (turbulence) and diffusion This… …or That Dispersion affected by stack height, building locations, and topography

10. Surface conditions TerrainTopography Planetary boundary layer and surface roughness

11. Convection Plume rise = buoyancy Ambient vs exit temperature affect air movement

12. Turbulence & eddies Moving objects move air molecules - cause currents

13. Physics & chemistry meet Reflection, absorption and deposition

14. Which Chemicals? Source type Chemical Reactions CH4 + OH ---> CH3 + H2O CH3 + O2 ---> CH3OO CH3OO + NO ---> CH3O + NO2 CH3O + O2 ---> HCHO + HO2 h ( HCO + H HCO + O2 ---> CO + HOO H + O2 ---> HOO Mechanisms: Oxidation and reduction, thermal, photochemical, hydrolysis

15. Understand model limits & assumptions

16. Many Models Available Dispersion Models: HYSPLIT, AERMOD, ISCST3, CALPUF Photochemical Models: CMAQ, CAMx, REMSAD, UAM-V® Receptor Models: CMB, UNMIX, PMF Many, many others

17. Terms & Concept review Advection Diffusion Domain (area vs computer) Conservative Reactive Kinetic Discrete (vs continuous) Receptor Albedo Anthropogenic Deposition – Wet vs Dry Lumped parameters Algorithm Laminar Photochemical

18. What is purpose in modeling? Physical, Chemical, and Biological processes can be modeled

19. Model’s View of World Chemical Processes Reactive or conservative Chemical of Concern Biological impact Mathematical Processes – Eulerian, Lagrangian, – Gaussian – Time scale Physical Processes Meteorology – Wind Speed, Direction – Solar energy = reactions – Precipitation Topography/Geography Deposition mechanisms Source Type

20. Summary Models convert numerical representation of system to concentration map or picture – Scale of problem; time and space – Controlling processes; meteorology, topography, and source – Available data; quality and quantity