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Simulation of Wintertime High Ozone Concentrations in Southwestern Wyoming

Ralph E. Morris, Susan Kemball-Cook, Bonyoung Koo, Till Stoeckenius and Greg

YarwoodENVIRON International Corporation

Novato, California

2009 CMAS ConferenceOctober 19-21, 2009

Chapel Hill, North Carolina

CMAS 2009 2

Increased Demand for Domestic Energy Production

Source: Wyoming Oil and Gas Conservation Commission

Wyoming Natural Gas Production: 1978-2008

CMAS 2009 3

High Ozone in Winter in SW Wyoming

• In 2005, WDEQ began monitoring in Jonah-Pinedale Area and found high wintertime ozone concentrations

• Field studies in 2007, 2008 and 2009

8-Hour Ozone Measured at the Jonah Monitor in Southwest Wyoming: February, 2005

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Day

8-H

ou

r O

zon

e (

pp

b)

Jonah: Feb 3, 2005Feb 3

CMAS 2009 4

Wyoming showing Pinedale and Wind River Range Northeast of Pinedale

CMAS 2009 5

SW Wyoming Oil and Gas Development

CMAS 2009 6

Monitoring Sites and O&G Wells in SWWY

CMAS 2009 7

Southwest Wyoming

Jonah Gas Field

CMAS 2009 8

Jonah Area in 1986

CMAS 2009 9

Jonah Area in 1999

CMAS 2009 10

Jonah Area in 2007

CMAS 2009 11

Upper Green River Ozone Study Monitoring Sites during 2009 Field

Study

• Mesonet Sites

• Permanent Sites (except Jonah & Boulder2)

• HRA Sites

CMAS 2009 12

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Ozo

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BoulderJonahDanielYellowstonePinedale

Monitored Monthly Maximum 8-Hour Ozone

Upper Green Winter PeaksUpper Green Winter PeaksUpper Green Winter PeaksUpper Green Winter PeaksUpper Green Winter Peaks

2005 2006 2007 2008 2009March

CMAS 2009 13

Unique Features of SWWY Ozone Episodes

•Winter events– Low sun angle– Cold

temperatures

•Snow Cover•Rural location•Significant oil

& gas development

CMAS 2009 14

Role of Mixing Heights

• Elevated O3 when MH < 150 m AGL

• Note SODAR max range = 250 m agl

SODAR Mixing Height

Peak 8-Hr Avg O3 at Boulder

2008 Data

CMAS 2009 15

UV Radiation and Snow Cover

2 March: Albedo = 0.8 (snow)

23 March: Albedo = 0.06 (bare ground)

UGWOS ’07 Data

CMAS 2009 16

Effects of Albedo on Photolysis Rates using CMAQ JPROC Program (JPROC

default Albedo = 0.05)NO2 Photolysis Rates

00.10.20.30.40.50.60.70.8

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ate

July 18

January 18

Recall Tyler Cruickshank (UDEQ/DAQ) Talk at 2008 CMAS Conference

0.50 snow Albedo used in Base Case

0.75 SWWY Albedo 6 Factor analysis

CMAS 2009 17

Average TNMHC Mixing Ratio and Sample Composition

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Boulder Jonah SODAR

Location

ppbC

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perc

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ges

(%)

TNMHC (ppbC)

Paraffins +Isoparaffins (%)Olefins (%)

Aromatics +Napthlenes (%)Oxygenates(%)C8-C12Organics (%)Unidentified(%)

2009 Data

CMAS 2009 18

CAMx Modeling Domains: 2005 & 2006

• MM5/SMOKE• 36 km domain provided

BCs to 12 km domain• 12/4 km domains run with

two-way grid nesting

CMAS 2009 19

Wintertime Ozone Sensitivity Tests

• WDEQ field study and analysis show the following six factors are associated with high winter ozone in SWWY:

1. Shallow inversion (limited mixing)2. White snow on ground (high albedo)3. Few or no clouds4. Stagnant and/or recirculating slow surface winds– Large amount of oil & gas development activity

producing:5. High TNMHC concentrations (e.g., ~3,000 ppbC)6. High TNMHC/NOx Ratios (e.g., ~90:1 at Jonah)

• Perform initial CAMx base case simulation running the model “out of the box” for the February 2006 high ozone period

CMAS 2009 20

CAMx Base Case – Jonah, Feb 18-28, 2006

• CAMx Base Case underestimates the February 25-27 peaks by ~30-40 ppb

56_035_JONA

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Julian Date (local time)

O3

(pp

b)

Obs

Base

Feb 19 Feb 25Feb 26 Feb 27

CMAS 2009 21

Account for 6 Factors for Wintertime Ozone

1. Shallow Inversion– Cap MM5 PBL heights in Jonah-Pinedale

area on episode days to 100 m AGL

2. White snow on Ground– Spatially varying CAMx snow cover input

file developed based on observations– Increase snow Albedo from 0.50 to 0.75

based on field study observations

3. Few or No Clouds– Eliminate MM5 cloud cover

CMAS 2009 22

Account for 6 Factors for Wintertime Ozone

4. Stagnant and/or Recirculating Slow Surface Winds

– MM5 winds already fairly slow

5. High TNMHC Concentrations (several 1,000s ppbC)

6. High TNMHC:NOx Ratio (~90:1) – Emissions Inventory TNMHC:NOx ratio in Jonah-

Pinedale area 13:1– Field Study 6-9am measured TNMHC:NOx at Jonah

averages ~90:1 on high ozone days– Multiply TNMHC emissions in Jonah-Pinedale area

by factor of 3 (3xTNMHC)

CMAS 2009 23

Winter Ozone 6 Factor Sensitivity Test Results

• Grey Line = Observed Hourly Ozone• Red Line = CAMx Base Case• Blue Line = CAMx 6 Factor Sensitivity Test

Jonah Boulder56_035_BOUL

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Julian Date (local time)

O3

(pp

b)

Obs

Base

6 Factors

56_035_JONA

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6 Factors

CMAS 2009 24

Daily Maximum 8-Hour Ozone (ppb)February 27, 2005

Base Case 6 Factor Sensitivity Case

CMAS 2009 25

6-9am TNMOC Concentrations (ppbC)February 27, 2005

Field Study ~1000s @ Jonah on high ozone daysBase Case 6 Factor Sensitivity Case

JJ

CMAS 2009 26

6-9am TNMOC:NOx RatiosFebruary 27, 2005

Field Study ~90:1 @ Jonah on high ozone daysBase Case 6 Factor Sensitivity Case

JJ

CMAS 2009 27

Winter Ozone Sensitivity TestsTest Effect of Each of the 6 Factors

• 6 Factor Sensitivity Test– Cap MM5 PBL depths in Jonah/Pinedale at 100 m

AGL– Removed MM5 clouds from met inputs– Increase snow Albedo from 0.50 to 0.75– 3xTNMOC emissions in Jonah/Pinedale to better

match field study TNMOC concentrations and TNMOC:NOx Ratio

• Sens#1: Original MM5 PBL Depths

• Sens#2: Original MM5 PBL Depths and Clouds

• Sens#3: Original MM5 PBL and Clouds & 0.50 Snow Albedo

CMAS 2009 28

February 26, 2005100 m cap - MM5 PBL No Clouds - MM5 Clouds

0.75 - 0.50 snow Albedo 3xTNMOC - 1xTNMOC

CMAS 2009 29

February 27, 2005100 m cap - MM5 PBL No Clouds - MM5 Clouds

0.75 - 0.50 snow Albedo 3xTNMOC - 1xTNMOC

CMAS 2009 30

Conclusions

•Using MM5/CAMx “out-of-the-box” fails to produce high wintertime ozone in SWWY

•With addition of the “6 Factors” CAMx able to produce high winter ozone events in SWWY

• Increasing snow Albedo from 0.50 to 0.75 and increases TNMHC emissions 3x most important– 0.75 Albedo fully justified from field study– More refined wind modeling and better emissions

representation may be able to produce high morning TNMHC concentrations and TNMHC:NOx ratios

CMAS 2009 31

Acknowledgements

• The analysis of the photochemical modeling results would not have been possible without the results of the Wyoming Department of Environmental Quality (WDEQ) Air Quality Division (AQD) field study data and analysis that was conducted by the AQD and their contractors:– ENVIRON– T&B Systems– Meteorological Solutions, Inc.– Argonne National Laboratory

• SWWY O&G emissions were developed by BP America and Sage Consulting, which has also been integral to this analysis