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IMPACTS OF MODELING CHOICES ON RELATIVE RESPONSE FACTORS IN ATLANTA, GA. Byeong-Uk Kim, Maudood Khan , Amit Marmur , and James Boylan 6 th Annual CMAS Conference Chapel Hill, NC October 2 , 2007. Objective.

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impacts of modeling choices on relative response factors in atlanta ga

IMPACTS OF MODELING CHOICES ON RELATIVE RESPONSE FACTORS IN ATLANTA, GA

Byeong-Uk Kim, Maudood Khan, Amit Marmur, and James Boylan6th Annual CMAS ConferenceChapel Hill, NCOctober 2, 2007

objective
Objective
  • Investigate the effects of modeling choices on Relative Response Factors (RRFs) in Atlanta, GA
    • Horizontal grid resolution: 4 km and 12 km
    • Chemical Transport Model: CMAQ and CAMx
approach
Approach
  • Exercising typical SIP modeling
    • Model Performance Evaluation (MPE)
      • Measures and methods following the EPA’s guidance document (EPA, 2007)
    • Modeled Attainment Test
      • Relative Response Factors
  • Additional analyses
    • MPE with graphical measures
      • Partial implementation of PROMPT (Kim and Jeffries, 2006)
    • Investigation of day-by-day and site-by-site variation of model predictions
modeled attainment test
Modeled Attainment Test
  • Future Attainment Status is determined by Future Design Value (DVf)
    • DVf should be less than 0.85 ppm.
  • DVf = RRF x DVb

Where,

DVb is Baseline Design Value and

RRF is Relative Response Factor defined as

modeling system setup
Modeling System Setup
  • Base case modeling period
    • May 21, 2002 ~ Sep 13, 2002 UTC (3 spin-up days )
  • MM5 (v 3.x)
    • Pleim-Xiu model for Land-Surface interaction
    • Asymmetric Convective Mixing
  • SMOKE (v 2.x)
    • VISTAS Base G version 2 inventory
  • CMAQ and CAMx
    • Inputs made to be close to each model for a same grid configuration.

Georgia

slide7

4 km

7x7

array

for 4-km runs

12 km

time series2
Time series

O3

Mon Tue Wed Thur Fri Sat Sun

O3

time series3
Time series

NO2

Mon Tue Wed Thur Fri Sat Sun

ETH

time series4
Time series

O3

Mon Tue Wed Thur Fri Sat Sun

O3

slide14

NO2

Mon Tue Wed Thur Fri Sat Sun

ETH

spatial distribution 12km daily max 8 hr o 3
Spatial distribution (12km)Daily Max 8-hr O3

2002-06-12

2002-07-23

2002-07-24

CAMx

ppb

CAMx-CMAQ

ppb

relative response factors
Relative Response Factors

RRFs from max O3 nearby grid cell arrays

  • Two possible methods to calculate RRFs
    • Max value in “nearby” grid cell arrays
    • Value at each monitoring site grid cell
  • Spatially averaged RRFs vary from 0.891 to 0.897 by modeling choices
    • If DVb = 100 ppb, 0.001 difference in RRF will result in 0.1 ppb in DVf.
conclusion 1
Conclusion (1)
  • Reasonable performance with respect to statistical metrics by all four models, CMAQ and CAMx with 4-km and 12-km grids
    • 4-km emissions had 11% lower NOx in non-attainment areas
    • 4-km MM5 runs showed poor nighttime performance.
  • Higher biases during nighttime by CMAQ and during daytime by CAMx
    • Gross overestimation of ozone by CAMx for several days
  • Lower biases from 4-km simulations
    • Probably due to emission discrepancies in 4-km inputs compared with 12-km emissions.
  • No significant daytime NOx biases
conclusion 2
Conclusion (2)
  • Stable or insensitive RRFs
    • Due to higher absolute concentrations predicted by CAMx, CAMx might show quite lower RRFs than CMAQ.
    • Max-Value based RRFs fell within 0.863 ~ 0.914 for all simulations.
  • Effect of RRF calculation methods
    • Despite of noticeable differences between 4-km and 12-km modeling inputs, Max-Value based RRFs does not reflect this fact significantly.
    • Cell-Value based RRF distinguished grid configuration differences.
    • For all 11 monitoring sites, maximum RRF difference due to model choices were 0.036 and 0.033 by Max-Value based and Cell-Value based RRF calculation.
future work
Future Work
  • Process Analysis to explain large variation of predicted ozone concentrations with similar modeling inputs
  • Detail study on the relationship between model performance including day-by-day and site-by-site meteorological model performance and RRFs
slide20

Acknowledgement

  • ENVIRON International Corporation
    • Ralph Morris for CMAQ-to-CAMx utilities
slide21

Contact Information

Byeong-Uk Kim, Ph.D.Georgia Environmental Protection Division4244 International Parkway, Suite 120Atlanta, GA 30354Byeong_Kim@dnr.state.ga.us 404-362-2526