effects of emission adjustments on peak ground-level ozone concentration in southeast texas jerry...
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Effects of Emission Adjustments on Peak Ground-Level Ozone Concentration in Southeast Texas
Jerry Lin, Thomas Ho, Hsing-wei Chu, Heng Yang, Santosh Chandru, Nagesh
Krishnarajanagar, Paul Chiou, and Jack R. Hopper
Lamar University2003 CMAQ Users’ Workshop
October 28, 2003
Lamar University
Motivation Air quality in southeast Texas metroplex
among the worst in the nation Ongoing debates on the contribution to
air quality problems from various emission sources
To investigate the impact of emission adjustments on peak ground-level ozone levels in Houston-Galveston and Beaumont-Port Arthur airshed
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Models & Inputs
Emission Inventory: NEI99 Final Version 2 pasted with Texas EI by Texas Commission on Environmental Quality.
Meteorological Fields: TexAQS 2000 MM5 meteorology (TCEQ/TAMU) – August 22 to September 2, 2000.
Emission Model: SMOKE 1.5 with MIMS spatial surrogate for gridded emission processing.
Chemical Mechanism: SAPRC99 mechanism. Chemical Transport Model: CMAQ June 2002 Release on
Linux platform. Data Analysis & Visualization: PAVE and Matlab with
netCDF/statistics toolboxes.
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Domain and Approach 87 87 Lambert Conformal
grids. 12-km grid resolution. Period: August 22-26, 2000. Texas point source VOC
scaled up for base case simulation.
Modeled O3 levels compared to field observations made by TCEQ.
Sensitivity simulations based on same input meteorology but varied emission adjustments.
Beaumont
Galveston
Houston
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Base-case Simulation (8/25/2000)
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Statistics for Data Analysis
M e a n b i a s ( M B ) ),(),(mod txatxa obs
M e a n n o r m a l i z e d b i a s ( M N B ) )),(
),(),(( mod
txa
txatxa
obs
obs
M e a n f r a c t i o n a l b i a s ( M F B ) )),(),((5.0
),(),(
mod
mod
txatxa
txatxa
obs
obs
M e a n a b s o l u t e g r o s s e r r o r ( M A G E ) ),(),(mod txatxa obs
M e a n n o r m a l i z e d g r o s s e r r o r ( M N G E ) )),(
),(),(( mod
txa
txatxa
obs
obs
U n p a i r e d p e a k p r e d i c t i o n a c c u r a c y ( U P A ) max
maxmaxmod
),(
),(),(
txa
txatxa
obs
obs
C o r r e l a t i o n c o e f f i c i e n t ( R ) 5.02
5.02
modmod
modmod
)),(()),((
)),(()),((
obsobs
obsobs
atxaatxa
atxaatxa
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Base-case Verification
Parameters Houston-Galveston
Beaumont-Port Arthur
Mean bias (MB), ppbv -2.72 4.08
Mean normalized bias (MNB), % DNC* DNC*
Mean fractional bias (MFB), % - 9.36 14.8
Mean absolute gross error (MAGE), ppbv 10.8 9.07
Mean normalized gross error (MNGE), % DNC* DNC*
Unpaired peak prediction accuracy (UPA), % 1.01 6.45
Correlation coefficient (R) 0.894 0.897
*: DNC – did not calculate due to zero ozone concentration in observation.
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Scatter Plots – August 25, 2000
Houston-Galveston Beaumont-Port Arthur
17 monitoring stations 4 monitoring stations
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Sensitivity Cases
Case No. Emission Adjustment
1 Remove Texas point source VOCs
2 Remove Texas mobile source VOCs
3 Remove Texas area and non-road source VOCs
4 Remove Texas point source NOx
5 Remove Texas mobile source NOx
6 Remove Texas area and non-road source NOx
7 Remove biogenic source VOCs and NOx for entire domain
8 Remove Texas mobile source CO
9 Reduce 50% of anthropogenic VOCs and NOx for entire domain
10 Reduce 50% of anthropogenic NOx for entire domain
11 Reduce 50% of anthropogenic VOCs for entire domain
12 Remove anthropogenic VOCs and NOx in non-Texas region
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Impact on Peak O3
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Ozone Difference for Cases 1 & 4
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Ozone Difference for Cases 5 & 6
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Ozone Difference for Cases 7 & 12
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Summary Removing point source emissions (VOC or NOX)
leads to the greatest reduction in peak O3 concentration.
The impact of point source emissions on O3 concentration only affect a small urban area for a relatively short period of time.
Removing area, mobile or biogenic source emission (VOC or NOx) causes O3 reduction in a larger area. However, the magnitude of reduction is less than that of point sources.
Transport from adjacent states may contribute significantly to the BPA O3 levels.
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Acknowledgement Texas Commission on
Environmental Quality (Work Order #48561-03)
Texas Air Research Center Prof. Daewon Byun at University of
Houston Alison Eyth at Carolina
Environmental Program