1 presents:/slides/ colorado and new mexico early action compact modeling analysis ralph morris and...
TRANSCRIPT
Presents:/slides/1
Colorado and New Mexico Early Action Compact Modeling Analysis
Ralph Morris and Gerard MansellENVIRON International Corporation
andDennis McNally and T.W. Tesche
Alpine Geophysics, LLC
WESTARRural/Urban Ozone in the Western United States
March 9-11, 2004Salt Lake City, Utah
Presents:/slides/2
Some Key Participants
• Denver EAC• Ralph Morris, ENVIRON
– Project Manage• Denver RAQC
– Ken Lloyd– Gerald Dilley
• Colorado DPHE– Kevin Briggs– Barbara McRae– Sheila Burns– Mike Silverstein
• New Mexico EAC• T.W. Tesche, Alpine
– Project Manager• New Mexico ED
– Mary Uhl– Dave Dubois– Andy Berger– Gail Cooke
• Four Corners Ozone Task Force– Julia Barnes
Presents:/slides/3
Today’s Talk Content
• Commonalities in Denver and New Mexico EAC Modeling Analysis
• Denver EAC Modeling Analysis• New Mexico EAC Modeling Analysis• Sensitivity Modeling of Potential Missing Oil
and Gas Production HC Emissions– Performed as Part of the Oklahoma EAC Modeling
Presents:/slides/4
Denver/New Mexico EACCommon Science Team
Alpine Geophysics
• T.W. Tesche)– Project Manager – New
Mexico– Co-PI
• Dennis McNally• Cyndi Loomis
ENVIRON
• Ralph Morris
– Project Manager – Denver
– Co-PI
• Gerard Mansell• Edward Tai
Presents:/slides/5
Denver/New Mexico EACCommon Modeling Tools
• MM5 Meteorological Model– Common 36/12 km grid– Separate local 4/1.33 km (Denver) and 4 km (New
Mexico) grids
• EPS2x Emissions Model– NEI 1999 base inventory– Colorado emissions provided by CDPHE– Local Oil and Gas Emissions (COGA, NMOGA)
• CAMx Photochemical Grid Model
Presents:/slides/6
Denver/New Mexico EAC -- Common Episode and Regional 36/12 km Grid
• June – July 2002 Regional Episode• Embedded High 8-hr Ozone Episodes
Denver (4/1.33 km)
June 8 - 12, 2002
June 25 – July 1, 2002
July 18 – 21, 2002
New Mexico (4 km)
June 4 –8, 2002
June 16 - 19, 2002
June 30 – July 2, 2002
July 17 - 18, 2002
Presents:/slides/7
Denver 36/12/4/1.33 km Modeling Domain(1.33 km grid not used)
Presents:/slides/8
New Mexico 36/12/4 km Modeling Domain
Presents:/slides/9
Differences in Denver and New Mexico EACs
• Both regions were attaining the 8-hour ozone standard at the initiation of the studies in early 2003
• During 2003, ozone remained relatively low in the Four Corners region; maximum 8-hour ozone Design Value during 2001-2003 is 74 ppb (attainment < 85 ppb)
• During 2003, Denver had the worse summer for ozone in many years; three monitors now violate the 8-hour ozone standard based on 2001-2003 data:– 87 ppb @ Rocky Flats North– 85 ppb @ Chatfield– 85 ppb @ South Boulder
Presents:/slides/10
Denver EAC Modeling Timeline
May 2003: Modeling Protocol (includes episode selection)
July 2003: MM5 Meteorological Modeling Report
During Summer 2003 8-hr ozone standard violated
Sep 2003: 2002 Emissions Inventory Report and Addendum
Oct 10, 2003: Modeling Review Panel (MRP) Meeting
Nov 19, 2003: 2002 Base Case/Evaluation Report
Dec 10, 2003: Modeling Review Panel (MRP) Meeting
Dec 2003: Preliminary 2007 Modeling
Jan-Feb 2004: Revised 2007 Base Case and Control Strategy Modeling
Feb 4, 2004: Report on 2007 Emission Reduction Sensitivity Modeling
Feb 27, 2004: Report on 2007 Control Strategy Modeling
Feb 27, 2004: Draft EAC Ozone Action Plan
Mar 2004: Preliminary Ozone Source Apportionment Modeling
Presents:/slides/11
CAMx Base Case Evaluation
• Follow EPA Draft 8-Hour Ozone Modeling Guidance Evaluation Procedures– Big Picture Graphical Performance
• Spatial Maps of Predictions and Observations• Scatter and Q-Q Plots• Time Series Plots
– Ozone Metrics• New 8-Hour Ozone Performance Metrics• Performance Goals
• Initial Evaluation for Ozone Only
Presents:/slides/12
Denver Ozone Monitoring Network
Presents:/slides/13
2002 Base Case 8-Hour Ozone on July 1, 2002
-808 -772 -736 -700 -664 -628 -592-136
-100
-64
-28
8
44
80
8 28 5
7 0
7 3
7 5
8 9
9 17 4 6 8
7 1
7 8
8 79 5
0
50
55
60
65
70
75
80
85
90
95
m ax = 87 PPBm in = 50 PPB
CAMx Daily Maximum 8hr O3July01, 2002
36/12/4 Denver 2002 Base Case run11a
Modeled ozone near monitor matches observations
Spatial displacement of modeled ozone away from DMA
DMA ozone suppression overstated
Presents:/slides/14
EPA Draft 8-Hour Ozone Guidance Performance Goals (EPA, 1999)
“bias pred/obs mean 8-hr (& 1-hr) daily maxima near each monitor”
“~20% most monitors (8-hr comparisons only)”
“fractional bias pred/obs mean 8-hr (& 1-hr) daily maxima near each monitor”
“~20% most monitors (8-hr comparisons only)”
“correlation coefficients, all data, temporally paired means, spatially paired means”
“moderate to large positive correlations”
“bias (8-hr daily max and 1-hr obs/pred), all monitors”
“~5-15%”
“gross error (8-hr daily max and 1-hr obs/pred), all monitors”
“~30-35%”
“Scatter plots & Q-Q plots of 8-hr and 1-hr metrics”
Presents:/slides/15
EPA 8-Hour Ozone Performance Metrics
• “bias pred/obs mean 8-hr (& 1-hr) daily maxima near each monitor” (EPA, 1999)
• “~20% most monitors (8-hr comparisons only)” (EPA, 1999)– How to define “near”? – Use same NX by NY array
of grid cells centered on monitor with 15 km radius as used in the attainment test (e.g., 9 by 9 for 4 km grid)
– What predicted ozone to select for comparison with observed maxima? – several approaches, including:• Maximum ozone near monitor (same as used in the
attainment test)• Nearest ozone near monitor (closest to observation)
Presents:/slides/16
Max Predicted 8-Hr Ozone Near Monitor – June 2002 Episode and 2002 Base Case – 4 km
• EPA Performance Goal of within ±20% at “most monitors”
• ~96% of Max Pred near monitor <±20% of observed value
• 3 pred/obs pairs do not meet <±20% goal (Weld Cnty 6/26; CO Springs 6/28; and Boulder on 7/1)
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140
Observed Ozone (ppb)
Pre
dict
ed O
zone
(pp
b)
r2=0.3042
O - - O shows quantiles
Presents:/slides/17
Nearest Predicted 8-Hr Ozone Near Monitor – June 2002 Episode and 2002 Base Case – 4 km
• EPA Goal <±20%
• ~98% of pred/obs pairs meet <±20% goal
• Weld Cnty 6/26 pred/obs of 57/81 ppb
•CO Springs 6/28 pred/obs of 57/74 ppb
•Meets goal with underprediction tendency
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140
Observed Ozone (ppb)
Pre
dict
ed O
zone
(ppb
)
r2=0.523O - - O shows quantiles
Presents:/slides/18
Summary of 2002 Base Case Ozone Performance for Denver June 2002 Episode
• Meets EPA performance goals– > 95% of monitor/days meet EPA’s performance goal < ±20% – EPA Bias and Gross Error performance goals (15% & 35%) met using
maximum and nearest predicted 8-hr ozone near the monitor– Underestimation bias sometimes exceeds <15% performance goal but
gross error always meets <35% performance goal using spatially paired pred/obs 8-hr ozone at the monitor
• Some ozone spatial alignment issues• Underestimation bias (but within performance goals)
– Understated ozone transport?– Understated emissions?
• Model performance for July 2002 episode was not as good so dropped for initial control strategy evaluations
Presents:/slides/19
2007 Emission Reduction Sensitivity Analysis• Across-the-Board 10% reduction in anthropogenic
emissions in DMA + Weld County (plus on-road and off-road reductions).
• Key Findings:– Modeled ozone stiff response to local emission
reductions (i.e., ozone not very responsive to local emission controls)
– VOC control in DMA is more effective than NOx control in DMA
• 10% VOC control in DMA results in 0.3-0.4 ppb ozone reduction at Rocky Flats North monitor
• 10% NOx control in DMA results in 0.4 ppb ozone increase at Rocky Flats North monitor
Presents:/slides/20
2007 Emission Scenarios• 2007 Base Case – CO Data Provided by CDPHE
– 9 psi RVP gasoline w/ 25% Ethanol penetration
• 2007 Control Package w/ 8.1 RVP• 2007 Control Package w/ 7.8 RVP• Control Measures Modeled (DMA + Weld County)
– 37.5% control on Flash VOC emissions– Control of RICE natural gas units and Dehydrators– 8.1 or 7.8 psi RVP gasoline on-road mobile sources in
DMA with 25% Ethanol market penetration
Presents:/slides/21
2007 Emissions Scenarios DMA+WeldVOC Emissions (tons per day)
DMA+Weld = Adams, Arapahoe, Broomfield, Boulder, Denver, Douglas, Jefferson and Weld Counties.
On-road mobile includes extra areas in link based network and should be ~65% for DMA+Weld counties
2007 2007 Control Pkg. w/ 8.1 RVP 2007 Control Pkg. w/ 7.8 RVP Base Control Reduction Control Reduction
Source Category (tpd) (tpd) (tpd) (%) (tpd) (tpd) (%) Area 137.70 137.70 0.00 0% 137.70 0.00 0% On-Road 154.28 138.06 -16.21 -11% 134.82 -19.46 -13% Off-Road 71.66 71.66 0.00 0% 71.66 0.00 0% Points 220.42 159.65 -60.77 -28% 159.35 -61.07 -28% Total 584.06 507.08 -76.98 -13% 503.53 -80.53 -14%
Presents:/slides/22
2007 Emissions Scenarios DMA+WeldNOx Emissions (tons per day)
DMA+Weld = Adams, Arapahoe, Broomfield, Boulder, Denver, Douglas, Jefferson and Weld Counties.
On-road mobile includes extra areas in link based network and should be ~65% for DMA+Weld counties
2007 2007 Control Pkg. w/ 8.1 RVP 2007 Control Pkg. w/ 7.8 RVP Base Control Reduction Control Reduction
Source Category (tpd) (tpd) (tpd) (%) (tpd) (tpd) (%) Area 6.92 6.92 0.00 0% 6.92 0.00 0% On-Road 176.30 175.78 -0.52 0% 175.78 -0.52 0% Off-Road 104.16 104.16 0.00 0% 104.16 0.00 0% Points 145.90 129.31 -16.60 -11% 129.31 -16.60 -11% Total 433.28 416.17 -17.11 -4% 416.17 -17.11 -4%
Presents:/slides/23
Daily Max 8-Hour Ozone on July 1, 2002 2007 Base 2007 Cntl Pkg w/ 8.1 RVP - Base
-808 -772 -736 -700 -664 -628 -592-136
-100
-64
-28
8
44
80
0
50
55
60
65
70
75
80
85
90
95
m ax = 86 PPBm in = 50 PPB
CAMx Daily Maximum 8hr O3July01, 2002
2007 Denver Base Case. 4km
-808 -772 -736 -700 -664 -628 -592-136
-100
-64
-28
8
44
80
- 3
- 2
- 1
- 0 . 8
- 0 . 6
- 0 . 4
- 0 . 2
0 . 2
0 . 4
0 . 6
0 . 8
1
2
3
m a x = 9 . 5 5 P P Bm i n = - 1 . 7 9 P P B
CAMx Difference in Daily Max 8hr O3July01, 2002
2007 Difference from Base Case using 8.1 RVP with 25% Ethanol
Presents:/slides/24
How Are Modeling Results Used to Demonstrate Attainment of the 8-Hour Ozone NAAQS
• EPA Draft Guidance uses model in a relative sense to scale current-year observed 8-hour ozone Design Values (DVC) to the future-year (DVF)
• This is done using monitor specific Relative Reduction Factor (RRFi) that is the ratio of the future-year to current-year 8-hour ozone model estimates near the monitor
DVFi = RRFi x DVCi
Presents:/slides/25
How Are Modeling Results Used to Demonstrate Attainment of the 8-Hour Ozone NAAQS
• The RRFi for monitor i is the ratio of the average daily maximum 8-hour ozone concentrations near the monitor for the future-year (O3F) to the current-year (O3C) scenario for all episode days when the current-year ozone is greater than 70 ppb (O3Cij > 70 ppb)
j
ij
j
iji C3OF3ORRF
Presents:/slides/26
How Are Modeling Results Used to Demonstrate Attainment of the 8-Hour Ozone NAAQS
• Selecting maximum estimated ozone “near” the monitor– Near defined by NX x NY array of cells centered
on monitor that encompasses 15 km radius– 5 km 7 x 7; 4 km 9 x 9; etc.
• Exclude days in which 2002 Base Case estimated 8-hr ozone near monitor is < 70 ppb– Eliminates low ozone (background) days with low
emissions contributions
Presents:/slides/27
2007 Projected 8-Hour Ozone Design ValuesAttainment Demonstrated when DVF < 85.0 ppb
2001-2003 2007 Scenarios (Days > 70 ppb)
Observed Base Case
Control Pkg. w/ 8.1 RVP
Control Pkg. w/ 7.8 RVP
Monitor DV (ppb) Scaled Scaled Weld County Tow 81 79.7 79.2 79.2 Rocky Mtn. NP 81 79.2 78.7 78.6 Fort Collins 71 70.5 70.0 70.0 USAF Academy 73 70.4 70.2 70.2 Welch 70 68.9 68.6 68.6 Rocky Flats Nor 87 86.5 86.0 86.0 NREL 85 84.5 84.1 84.0 Arvada 76 75.8 75.4 75.4 Welby 66 66.5 66.0 65.9 S. Boulder Creek 77 76.5 76.1 76.0 Carriage 76 75.1 74.7 74.7 Highland 81 79.7 79.3 79.3 Chatfield Res. 85 83.4 83.0 82.9
Presents:/slides/28
Denver EAC – Modeled Attainment Test • Projected 2007 8-hour ozone Design Value at
Rocky Flats is 86.5 ppb for 2007 Base Case and 86.0 ppb for 2007 Control Strategies
• All other monitors demonstrate attainment (< 85 ppb)
• Why is modeled ozone so stiff?– Contributions of ozone transport– 2002 episode not as adverse as conditions that
produced observed Design Values that includes summer 2003
– Model underestimation bias
Presents:/slides/29
Ozone Source Apportionment10 Source Regions in 36 km West US Grid
-2304 -2088 -1872 -1656 -1440 -1224 -1008 -792 -576 -360 -144 72 288-1404
-1296
-1188
-1080
-972
-864
-756
-648
-540
-432
-324
-216
-108
0
108
216
324
432
540
1 0
98
77
6
13
45 2
1. DMA
2. Weld
3. Elbert
4. Morgan
5. Larimer
6. El Paso
7. North CO
8. South CO
9. Central US
10. Western US
Presents:/slides/30
Denver Ozone Source Apportionment • Source Apportionment results currently under
review by State and Denver RAQC, report not yet available
• Preliminary results suggest the following:– A majority (~75% to 85%) of the peak 8-hour ozone
concentrations at the Rocky Flats monitor come from outside of the Denver Metropolitan Area (DMA)
– For sources in the DMA, on-road mobile sources are most important followed by non-road mobile sources
• Helps explain why modeling results are so stiff in response to local controls
Presents:/slides/31
Weight of Evidence (WOE) Attainment Demonstration – Modeling Component
• EPA Draft 8-hr Ozone Guidance (EPA, 1999)– Modeled maximum 8-hr ozone Design Value must
be less than 90 ppb• Denver EAC 2007 Control Strategy maximum
projected 8-hour ozone Design Value = 86 ppb– Air Quality Modeling Analysis
• Change in grid-hours with ozone > 84 ppb• Change in Number grid cells > 84 ppb• Change in ppb-hr with ozone > 84 ppb
– Also other data analysis (meteorology, emissions, trends, etc.)
Presents:/slides/32
WOE Attainment Demonstration Issues
• Model is Stiff in Response to Local Controls– Model meets EPA performance goals (within 20%)
but has underprediction bias• Using some days with ozone estimates of 70-75 ppb
to scale 87 ppb Design Value at Rocky Flats– June 2002 episode not as adverse as observed
2001-2003 8-hr ozone Design Values that include the Summer of 2003
• Local emissions not contributing as much to the ozone maximums in the model as likely occurred in the observed ozone Design Values
Presents:/slides/33
Modeled WOE Attainment Demonstration Tests• Project 2007 8-hour ozone Design Values (DVs)
using modeled ozone > 80 ppb– Modeled ozone more representative of ozone DVs– 2007 Projected 8-hour ozone at Rocky Flats is
• = 85.4 Control Pkg. w/ 8.1 RVP• = 85.2 Control Pkg. w/ 7.8 RVP
• Project 2007 DVs using observed 2000-2002 DVs– Conditions more consistent with June 2002 episode
Monitor 2007 Base Case 2007 Control Pkg. w/8.1 RVP
2007 Control Pkg. w/7.8 RVP
Rocky Flats 83.7 83.1 83.0 NREL 81.7 81.1 81.1 Chatfield 78.8 78.1 78.1
Presents:/slides/34
Modeled WOE Attainment Demonstration Tests• EPA Guidance WOE Metrics
– # Grid-Hours > 84 ppb• Integrated exposure metric of modeled exceedances
over time and area– # Grid-Cells > 84 ppb
• Integrated exposure metrics over area– Relative Reduction (RD) – Measure of amount of
time and area ozone > 84 ppb (ppb-hr)• Integrated dosage metric
• EPA Guidance States that “large” reductions in these metrics are desirable– EPA defines “large” as >= 80%
Presents:/slides/35
Modeled WOE Attainment TestsEPA Guidance Desires >=80%
Scenario
# Grid-Hours 8-hr > 84 ppb
# Grid-Cell > 84ppb
Relative Difference
(#) (%) (#) (%) (ppb-hr)
(%)
2002 Base 33 15 2007 Base Case 8 76% 6 60% 0.16 84% 2007 Control Strategy Pkg. w/8.1 RVP
4 88% 3 80% 0.08 92%
2007 Control Strategy Pkg. w/7.8 RVP
4 88% 3 80% 0.07 93%
Presents:/slides/36
Denver EAC WOE Attainment Tests
• Anomalous Meteorological Conditions of 2003 produced unusually high ozone– Unusually high temperatures during Summer 2003
• July 2003 4rth highest mean temperature on record
– Unusually low mixing depths trapped local pollutants causing high ozone
• Much higher contribution of local emissions to ozone than in 2002 episodes
Presents:/slides/37
Denver EAC WOE Attainment Tests
• Zurbenko-Rao filter applied to ozone at Rocky Flats to decompose ozone trends into long-term and short-term components accounting for temperature– Over 1993-2003 downward trend in 4rth highest 8-hr
ozone of –1.2% per year
Presents:/slides/38
Denver EAC WOE Attainment Tests
• Downward trend in emissions in the DMA– From 2002, VOC emissions are projected to be reduced
by –10% (2007) and –13% (2012)– From 2002, NOx emissions are projected to be reduced
by –15% (2007) and –19% (2012)• Model Uncertainty and Representativeness
– Model underestimation bias• Use of days > 80 ppb reduces DV from 86 ppb to 85 ppb
– Contributions of local emissions understated• 2003 observed DV of 87 has higher local contribution
than 2002 episodes
Presents:/slides/39
San Juan New Mexico EAC Study
Conceptual Model and Episode Selection 8-hr Ozone Modeling Protocol Meteorological Data Bases & Modeling Report Base Year (2002) Emissions Inventory Report Future Year (2007) Emissions Inventory Report Base Year Model Performance Evaluation Report Future Year (2007) Baseline Modeling Report
Year 2007 Maintenance for Growth Modeling Report Year 2007 Strategy Modeling Report
Presents:/slides/40
Location of San Juan Ozone Monitors
Presents:/slides/41
Daily Max 8-Hour Ozone
Maximum 8-hr Ozone For Each Embedded Episode
0
10
20
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50
60
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80
90
04
-Ju
n
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-Ju
n
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-Ju
n
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-Ju
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-Ju
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-Ju
n *
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-Ju
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-Ju
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Embedded Episode Day During 2002
Dai
ly M
axim
um
8-h
r O
zon
e (p
pb
)
Substation
Bloomfield
Mean Wind
Wind x 10, m/s
2001-2003 DV=74.7 ppb
Presents:/slides/42
1-Hr Ozone Model Performance, Bias – Goal < 15%
Mean Normalized Bias in 1- Hr Ozone, (%).
-30.0
-25.0
-20.0
-15.0
-10.0
-5.0
0.0
5.0
10.0
15.0
04-J
un
05-J
un
06-J
un
07-J
un
08-J
un
Ave
rage
Bia
s, %
4 km Domain12 Km Domain36 km DomainSan Juan Basin
Presents:/slides/43
1-Hr Ozone Model Performance, Error – Goal < 35%Mean Normalized Gross Error in 1- Hr Ozone, (%).
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
04-Jun
05-Jun
06-Jun
07-Jun
08-Jun
Avera
ge
Gro
ss E
rror
, %
4 Km Domain12 Km Domain36 km DomainSan Juan Basin
Presents:/slides/44
Summary 1-Hour Ozone Performance
• CAMx model produced 1-hr ozone model performance:– Well within EPA performance goals in all but a few cases;– Better than normal in a ‘first time application’ of a
photochemical modeling system to a new region; and – Consistent with known opportunities for data base
improvements (e.g., area source emissions, on-road motor vehicle emissions) in the local area (Four Corners) and surrounding region (western U.S.).Main concern with the four (4) San Juan base cases is the systematic tendency to underestimate ozone concentrations at some monitoring locations. This feature has been seen in other independent, corroborative modeling (CMAQ) employing similar emissions and meteorological modeling foundations.
Presents:/slides/45
EPA Draft 8-Hour Ozone Guidance Performance Goals (EPA, 1999)
Bias in daily maxima 8-hr predictions and observations
~20% at most monitors
Fractional bias in daily maxima 8-hr predictions and observations over several days
~20% at most monitors
Bias in 8-hr daily max and 1-hr daily average over all monitors
~5-15%
Gross error in 8-hr daily max and 1-hr daily average over all monitors
~30-35%
Scatter plots & Q-Q plots of 8-hr and 1-hr concentration distributions
Correlation coefficients based on all predictions-observations, paired in time and space
Moderate to large positive correlations (i.e., small variance)
Performance Metric Performance Goal
Presents:/slides/46
8-Hour Ozone Modeling Relative to EPA GoalsPerformance Metric Model Skill
Bias in daily maxima 8-hr predictions and observations over several days
Bias in daily max 8-hr predictions over 15 episode days is < 20% on 91% of the modeling days.
Fractional bias in daily maxima 8-hr predictions and observations over several days
Fractional bias in daily 8-hr predictions over the 15 episode days is < 20% on 83% of the modeling days.
Bias in 8-hr daily max and 1-hr daily average over all monitors
Bias for 8-hr & 1-hr predictions are –3.6% & -11.9%, meeting EPA goal
Gross error in 8-hr daily max and 1-hr daily average over all monitors
Gross errors for 8-hr & 1-hr predictions are 20.9% & 21.5%, meeting EPA goal
Scatter plots & Q-Q plots of 8-hr and 1-hr concentration distributions
Scatter and Q-Q plots do not exhibit spurious trends
Correlation coefficients based on all predictions-observations, paired in time and space
8-hr and 1-hr variance measures (131.0, 164.0) acceptably small
Presents:/slides/47
Trends in 8-Hour Ozone Design Values
2001-2003 Design Values:
Substation = 74.7 ppb
Bloomfield = 74.3 ppb
Presents:/slides/48
Projected 8-Hr Ozone Design Values for 2007 Base Case Emissions
Monitoring Obs DV AVG 2007Location RRF DV
Bloomfield 74.3 0.976 72.49Substation 74.7 0.996 74.37Ignacio 75.0 0.983 73.72Bondad 75.0 0.984 73.78Mesa Verde 69.0 0.995 68.65
Measured Daily Maximum 8-hr Ozone Concentration (ppb)
All projected 8-hour ozone Design Values in 2007 are < 85 ppb, so attainment has been demonstrated in San Juan, New Mexico
Presents:/slides/49
Additional Corroborative Analysis
• Model July 13-21, 1999 episode using alternative model– EPA’s Models-3 CMAQ model– MM5 Meteorology– NEI99 Emissions
• Also exhibits underestimation bias suggesting emissions may be understated in the western U.S. and possibly Four Corners region
Presents:/slides/50
Additional San Juan, NM Analysis
• Five 2007 Emission Scenarios– Addition of two more Power Plants– Accelerated Oil and Gas Field Development– Revised On-Road Mobile Sources– Area Source Emissions Uncertainty– Biogenic Emissions Uncertainty
• 2012 Base Case Modeling– Attainment Still Maintained
• Ozone Source Apportionment Modeling– Largest contribution from background ozone
Presents:/slides/51
National Academy of Sciences (NAS) Report
• “Extensive Regional Atmosphere Hydrocarbon Pollution in the Southwestern US”– Aaron Katzenstein, Lambert Doezema, Isobel
Simpson, Donald Blake and F. Sherwood Rowland, University of California at Irvine (UCI) (October 14, 2003)
• Collected many hydrocarbon samples in OK/KS/TX
• Found elevated alkane (HC) concentrations• Attributed to Oil and Gas production in region• Estimated regional-wide emission rates
Presents:/slides/52
UCI Ethane Observations(Source: Katzenstein et al., 2003)
Presents:/slides/53
UCI O&G Emissions Sensitivity Test-- Approach to Integrate UCI Emissions with
Photochemical Model• Contacted UCI who (Lambert Doezema) provided
a low and high estimate region-wide hydrocarbon emission estimates from their measurement grid– Methane, ethane, propane, n&i butane, n&i pentane
• Determine county equivalent to UCI measurement grid
• Allocate UCI O&G hydrocarbon emissions to counties based on average Oil&Gas production
• Methane considered non-reactive VOC so is dropped
Presents:/slides/54
UCI Measurement Grid
Presents:/slides/55
Presents:/slides/56
Presents:/slides/57
Comparison of Oil+Gas Production to NEI99 Oil+Gas VOC Emissions
Comparing 1999 inventory to fractions calculated from oil and gas production data - each point represents one county
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07
1999 existing inventory- % emis by county
0.5
(gas
pro
du
ctio
n%
)+0.
5(o
il p
rod
%)
1999 NEI Oil&Gas VOC Emissions
Average Oil and
Gas Production
Presents:/slides/58
UCI O&G Emissions Sensitivity Test
• Replace existing county-level Oil&Gas VOC emissions from NEI99 with UCI estimates allocated to OK/KS/TX/CO counties based on Oil&Gas production
• Process with EPS2x emissions to speciate, grid and temporally allocate emissions for CAMx modeling
• Run CAMx model for high and low estimates of UCI Oil&Gas HC emissions
• Compare ozone estimates
Presents:/slides/59
Comparison of NEI99 and UCI Oil&Gas Production VOC Emissions (tons per day)
1999 NEI UCI (%)
Colorado 0.0 21.9 --
Kansas 4.8 378.9 --
Oklahoma 120.6 949.5 +787%
Texas 397.0 1062.8 +267%
Total 522.4 2413.0 462%
Presents:/slides/60
Ozone Results using UCI O&G HC Emissions
• Very small increases in ozone concentrations, primarily downwind of NOx sources and near high Oil&Gas production– Maximum increase in 8-hour ozone concentrations
are 0.5-1.0 ppb– Small increases elsewhere
• No effect on model performance– Normalized bias of –10.1% reduced to –10.0%– Does not solve underprediction tendency
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Daily Max 8-Hour Ozone PerformanceNEI99 O&G VOC UCI O&G VOC
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Difference in 8-Hour Ozone Concentrations (ppb) from UCI Oil&Gas
HC Emissions
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UCI Oil&Gas HC Emissions Conclusions• Preliminary results still being examined• Use of UCI O&G VOC estimates results in
small increases in ozone (always < 1 ppb)• Just included potentially missing VOC
emissions, results may be different if potentially missing NOx emissions included
• Does not explain western U.S. ozone underprediction tendency seen in Denver, San Juan and Oklahoma EACs and with multiple models (CAMx and CMAQ)
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Overall Conclusions Western US O3 Modeling• Ozone downwind of smaller “urban” areas in
western U.S. tends to be underestimated– Seen in recent EACs (CAMx) and Regional Visibility
modeling (CMAQ)– Regional buildup of ozone understated
• Contributing factors:– Missing emissions
• UCI Oil&Gas, many small unpermitted sources• Missing biogenic emissions/understated reactivity• Mobile Source fleet type different from national average
– Meteorological Modeling More Challenging