This presentation compares the results of the CALPUFF model run with different model switches for regulatory permit application purposes.

1. Koray Önder, P.Eng., Senior Air Quality Engineer
Greg Unrau, M.Sc., Associate, Senior Air Quality Meteorologist
Rekha Nambiar, M.Eng., Air Quality EIT
Paper #869
CALPUFF Model Sensitivity Analysis
Model Switch Comparison

2. Outline
 Background
 Methodology
 Results and Discussions
 Sensitivity Analysis 1 : Individual Source Types
 Sensitivity Analysis 2 : Regional Cumulative Predictions
 Model Performance Evaluation
 Conclusion
 Questions
2

3. Background
 New Alberta Environment (AENV) Modelling
Guideline (May 2009) stipulates EPA default
CALPUFF switches
 Any non-default switches have to be justified
 Previously:
 Most advanced switches turned “on” to use the
increased capability of the model
 Some switches were problematic (e.g., MSHEAR)
3

4. Background
 EPA recommends CALPUFF only for long range modelling
 Alberta allows CALPUFF for near field applications
 British Columbia and Ontario modelling guidelines allow
CALPUFF for near field applications
 Non-default ‘MDISP’ AND ‘MPDF’ switches are recommended for
near field applications
 Alberta Oil Sands Region: modelling efforts involve both
near field and long range (i.e., regional scale where
distances > 50km)
 Inconsistency in model switches for near field vs. long range
applications – Challenge!
4

5. Modelling Methodology
 CALPUFF version 6.263, level 080827
 MODIS (Moderate Resolution Imaging Spectroradiometer)
based geophysical data
 One year (2006) of meteorological data using local surface
and mesoscale model version 5 (MM5) output data
5

6. Modelling Methodology - CALPUFF Switches
6

7. Sensitivity Analysis 1
 5 different source types with 1 g/s emission rate:
 Steam Generator (30 m)
 Small Heater (9 m)
 Incinerator (100 m)
 Flare (90 m)
 Area source (e.g., Mine)
 Considered 5 CALPUFF switch combinations (MSPLIT, MSHEAR,
MDISP, MPDF, MCTURB)
7

8. Sensitivity Analysis 1 Results
June 28, 2012 8

9. Sensitivity Analysis 2
 Regional cumulative contributions from multiple sources
 2006 emissions – existing sources in the Oil Sands region
(monthly production/operational variance included)
 Three Cases Considered Based on Previous Results
 Case 1 – U.S. EPA Defaults
 Case 2 – Historic Oil Sands Switches
 Case 3 – Alternate Switches (no Puff Split)
 Modelling performed for two basic compounds:
 Sulphur Dioxide (SO2)
 Nitrogen Dioxide (NO2)
9

10. Sensitivity Analysis 2 Results
10

11. Model Performance Evaluation
 Regional cumulative emissions predictions compared with
Wood Buffalo Environmental Association (WBEA)
monitoring station network data
 Two model switch combinations
 Case 1 – U.S. EPA Defaults
 Case 2 – Historical Switches
 Case 3 – Alternate Switches (no Puff Split)
 Two Statistical Comparison methods
 Fractional Bias
 Normalized Root Mean Square Error (NRMSE)
11

12. Locations
 Emission Sources
272 Point Sources
39 Area Sources
 Modelling Domain
392 km by 564 km
12

13. Fractional Bias Values - SO2
13

14. Fractional Bias Values - NO2
June 28, 2012 14

15. NRMSE Values – SO2
15

16. NRMSE Values - NO2
16

17. Conclusions
 US EPA Default switches (Case 1) results lower – except
area sources
 Should not be generalized!
 Historic Switches (Case 2) – considerably higher predictions
 Alternate Switches (Case 3 - BC and ON guidelines) – in
between
 Model Performance Evaluation: No clear winner
 Results does not warrant recommending an alternate; however…
 Regulatory Compliance Modelling – Oil Sands Region:
 Using different switches not practical
 Both Near Field / Long Range – primary focus: near field
 BC and Ontario recommend alternate switches for near field
 Alternate Switches – conservative and newer science
17

18. Questions
Thank You!
Koray Önder konder@golder.com
Greg Unrau gunrau@golder.com
Rekha Nambiar rnambiar@golder.com
18