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Ozone Concentration and Meteorology at Lakeshore and Inland Monitors

Gail Good Director, Bureau of Air Management Wisconsin Department of Natural Resources

Analysis by Angela Dickens Policy Analyst Regional Pollutants and Mobile Sources Section WDNR Bureau of Air Management

Wisconsin Department of Natural Resources

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Question:

How quickly do ozone concentrations drop off inland from the Lake Michigan lakeshore?

Topics:

1. Background on ozone in Wisconsin

2. Concentration comparisons at inland and lakeshore monitors

3. The role of meteorology in driving ozone at these monitors

4. Applications to policy

Typical high-ozone day: • Synoptic transport of ozone/precursors • Onshore transport via the lake breeze

1. Background on ozone in Wisconsin

June 19, 2016

6am surface synoptic weather map Maximum daily 8-hour average ozone concentrations

What does a lake breeze look like?

Win

d d

irec

tio

n (

°)

Ozo

ne

(pp

b)

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1. Background on ozone in Wisconsin

Sheboygan Haven June 25, 2016

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August 3, 2016 MODIS satellite image

1. Background on ozone in Wisconsin

What does a lake breeze look like?

Photochemical modeling suggests high-ozone air stays near shore

Modeling by the Lake Michigan Air Directors Consortium (LADCO)

1. Background on ozone in Wisconsin

Sheboygan County Inland monitor: • Ozone & met data from 2014-2016 • 3.2 miles inland

Kenosha County Inland monitor: • Ozone data from 2013-2016 • Met data from 2014-2016 • 3.6 miles inland

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2014-16 DVs

2. Concentration comparisons at inland and lakeshore monitors

65

70

75

80

85

2012 2013 2014 2015 2016 2017

ozo

ne

co

nce

ntr

atio

ns

(pp

b) Kenosha County

lake-4th high

inland-4th high

lake-DV

inland-DV

65

70

75

80

85

2012 2013 2014 2015 2016 2017

ozo

ne

co

nce

ntr

atio

ns

(pp

b)

Sheboygan County

lake-4th high

inland-4th high

lake-DV

inland-DV

2. Concentration comparisons at inland and lakeshore monitors

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

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0.09

7/18/14 7/19/14 7/20/14 7/21/14 7/22/14 7/23/14

Ho

url

y o

zon

e c

on

cen

trat

ion

s (p

pb

)

lakeshore

inland

2. Concentration comparisons at inland and lakeshore monitors 1-hour concentrations – For a 2014 episode

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Slope = 0.79

Slope = 0.89

• Inland conc. ↑ with ↑ lakeshore conc. • Inland conc. trend lower than lakeshore

• Sheboygan: ≈ 79% • Kenosha: ≈ 89%

• High lakeshore concentrations: • Inland conc. don’t trend with

lakeshore • Really high concentrations don’t

seem to penetrate inland (mostly) • Higher inland ozone at Kenosha WT

versus Sheboygan Haven

2. Concentration comparisons at inland and lakeshore monitors 1-hour concentrations – All hours

Inla

nd

ozo

ne

co

nce

ntr

atio

ns

(pp

b)

0 10 20 30 40 50 60 70 80 90 100 Lakeshore ozone concentrations (ppb)

Sheboygan

Lakeshore Inland

3. The role of meteorology in driving ozone at these monitors Only hours with ozone >70 ppb at that site (different sets of hours at each monitor)

• Ozone-rich winds come from the south over the lake • Kenosha monitors also get

some ozone from over land

• Many fewer hours with high ozone inland (~⅓)

Kenosha

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Conclusions

• Lakeshore ozone concentrations are consistently higher than inland concentrations.

• These differences are the greatest at the highest lakeshore concentrations.

• The highest ozone air rarely reaches the inland monitors.

• Almost all ozone comes from the south over the lake

• A small amount at Kenosha comes from over land to the south

Overall: Ozone concentrations drop off sharply within a few miles of the lakeshore.

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Applications to Policy Submitted a Technical Support Document for 2015 ozone NAAQS designations

• Supporting the Governor’s recommendation of full attainment for the state

• Demonstrated the overwhelming role of transport to Wisconsin’s monitors

• Using technical data to estimate the extent of design values above 70 ppb

• Most of the lakeshore: 70 ppb contour is a few miles inland

• Milwaukee County: most of the county attained the NAAQS

• Racine County: not enough data

• Kenosha County: 70 ppb contour is farther inland due to direct overland transport from Chicago

• Northernmost lakeshore counties:

• Kewaunee County attained the NAAQS

• Only a small portion of Door County is estimated to exceed the NAAQS

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Application to policy – Kenosha County

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Application to policy – Sheboygan County

Application to policy – Wisconsin lakeshore

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Thank you! Questions?

Gail.Good@wisconsin.gov