The four studies highlighted in this issue of EM exemplify inter-agency and inter-statecooperative efforts to advance scientific understanding of air pollution near the land–water interface.

Recent Advances inUnderstanding Ozone Pollution

Near Large Water Bodies

em • The Magazine for Environmental Managers • A&WMA • October 2020

Cover Story by Susan Wierman, Leiran Biton, and Joel Dreessen

em • The Magazine for Environmental Managers • A&WMA • October 2020

Cover Story by Susan Wierman, Leiran Biton, and Joel Dreessen

The interplay between emissions and meteorology nearlarge water bodies requires in-depth technical analysis. Research has shown that high ozone (O3) concentrationscan form over water and affect both nearby and more distant coastal areas, and that high-resolution air qualitymodels are needed to represent local conditions more accurately.1,2 Though major regional and local reductions inO3 precursors have significantly improved air quality in theeastern United States, episodic high O3 events persist, particularly over large bodies of water and adjacent coastalareas, contributing to violations of the federal O3 standard.Motivating the four studies described in this issue werequestions about the relative importance of emissions fromnearby industrial or urban centers versus more distantsources of air pollution, the potential to use advanced monitoring techniques to better understand pollutionepisodes, and the importance of improving the ability of airquality models to simulate the fine-scale dynamics of theland–water interface. Scientists continue to stress the importance of measuring O3 aloft (as was done in studiesdescribed here) to help resolve questions about local andlong-distance transport of O3 and precursor pollutants.3

The U.S. Environmental Protection Agency (EPA) has recog-nized the value of short-term special studies, such as thosedescribed in this issue. When EPA adopted the 70 parts per

billion (ppb) 8-hr O3 National Ambient Air Quality Standard(NAAQS) in 2015, the agency also substantially revised the requirements for enhanced monitoring plans for O3 and itsprecursors. To help states develop plans to comply with newmonitoring requirements, in 2017 EPA published a “Techni-cal Note”4 describing optional long-term monitoring meth-ods, but also encouraging states to work collaboratively withother agencies to conduct short-term intensive monitoringcampaigns if needed to help understand the formation ofozone in their particular areas. The results of special studieslike these, along with other analytical techniques and information, can help air quality managers develop effectivepollution control measures.

The first study included in this issue focuses on the complexatmospheric chemistry and physics of Long Island Sound.High amounts of O3 precursors from the New York City met-ropolitan area and areas upwind are transported over theSound, where weak mixing allows intense O3 concentrationsto form. Then, an afternoon sea breeze transports the high O3

onshore in coastal Connecticut. As a result, the highest O3

levels in the region consistently are not seen in New York Cityitself, but downwind along coastal Connecticut. AlexandraKarambelas’s article describes the context for the 2018 LongIsland Sound Tropospheric Ozone Study (LISTOS). She alsolooks ahead to how these data will be used in modeling to

better understand and develop controls toreduce O3 pollution.

The next article focuses on the Baltimorearea, which has made steady progress to-ward attaining the EPA O3 standards in partdue to targeted regional emissions reduc-tions efforts such as the oxides of nitrogen(NOX) SIP Call and also due to Marylandregulations and the state’s Healthy Air Act.However, episodes of high O3 over andnear the Chesapeake Bay have kept the Baltimore area from attaining the 2015ozone standard. Sites northeast of Baltimoreand adjacent to the northern coast of theChesapeake Bay continue to be the highestreading O3 monitors in the area, despite improvements in other parts of the region.NASA’s Ozone Water–Land EnvironmentalTransition Study (OWLETS) intensive moni-toring programs focused on the ChesapeakeBay region, integrating in-situ and remotelysensed data from ground, water, air, andsatellite platforms. The article in this issue byJohn T. Sullivan and colleagues describes the2018 OWLETS-2 campaign. The highlights

Figure 1. Long Island Sound (July 28, 2019).Strong temperature gradients between the land and water onJuly 28, 2019, force a line of clouds along Long Island, whilekeeping the Long Island and Connecticut coastlines along theLong Island Sound cloud free. Every single coastal ConnecticutO3 monitor exceeded 70 ppb on this day, along with a NewYork monitor on the northern coast of Long Island.Source: True color imagery from VIIRS instrument on the Suomi NPPsatellite. NOAA JSTAR Mapper (https://www.star.nesdis.noaa.gov/jpss/mapper.).

presented in this article exemplify a special study integratedinto an Enhanced Monitoring Program implemented by thestate to assess the formation and transport of pollution overand near the Chesapeake Bay.

em • The Magazine for Environmental Managers • A&WMA • October 2020

Cover Story by Susan Wierman, Leiran Biton, and Joel Dreessen

Next, the article by Zac Adelman and col-leagues describes the 2017 Lake MichianOzone Study (LMOS), an important additionto ongoing efforts to better understand theformation and transport of O3 across andalong Lake Michigan. Despite many years ofair quality improvements, persistent air qualityproblems in meeting newer NAAQS remain.The questions addressed in this study in-cluded the relative importance of local and in-terstate pollution sources, the importance ofNOX and volatile organic compound (VOC)precursors, and how well air quality modelsrepresented atmospheric chemistry in theLake Michigan region. Contributions to O3

problems were traced to both anthropogenicand natural sources, and the study docu-mented how and when the importance ofVOC and NOX sources varied.

Finally, the article by Anne M. Thompsonand colleagues takes us to the Gulf of Mex-ico where NASA and the Bureau of OceanEnergy Management conducted the SatelliteCoastal and Oceanic Atmospheric PollutionExperiment (SCOAPE) to assess the utility ofsatellite data to help assess the impact of ex-

panded offshore oil and gas development. Satellite measure-ments of total column pollutants were compared to surfacemeasurements taken at oil and gas platforms and onboardthe University of Southern Mississippi’s Research Vessel

Figure 2. Chesapeake Bay (July 3, 2018).Differential heating between the land and water create visiblebay breezes on July 3, 2018, on both the Chesapeake andDelaware Bays. The OWLETS-2 campaign measured localizedO3 in excess of 90 ppbv over the northern Chesapeake Bay,resulting in 8-hr maximums around 80 ppbv. Similar O3 wasnot observed over the Delaware Bay. Source: True color imagery from VIIRS instrument on the Suomi NPPsatellite. NOAA JSTAR Mapper (https://www.star.nesdis.noaa.gov/jpss/mapper).

In Next Month’s Issue…Background OzoneAir pollution regulators use “background ozone” to describe ozone originating from sources outside oftheir control. In the United States, background ozone has been defined as originating from transport ofozone from the stratosphere, ozone formed from natural precursor sources (lightning, fires, biogenicsources, etc.), and ozone formed from international anthropogenic precursors. Quantifying backgroundozone is complicated by the fact that many emissions sources are impacted by both anthropogenic andnatural processes. The November issue explores the current state of understanding regarding background ozone.

em • The Magazine for Environmental Managers • A&WMA • October 2020

Cover Story by Susan Wierman, Leiran Biton, and Joel Dreessen

Point Sur. Under the conditions of their May 2019 sampling, O3 levels were higher closer to shore, influencedby the New Orleans–Baton Rouge region, than over the Gulf.

References1. Loughner, C.P.; Tzortziou, M.; Follette-Cook, M.; Pickering, K.E.; Goldberg, D.; Satam, C.; Weinheimer, A. ; Crawford, J.H.; Knapp, D.J.; Montzka, D.D.;

Diskin, G.S.; Dickerson, R.R. Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export; J. Appl. Meteorol. Climatol. 2014, 53, doi:10.1175/JAMC-D-13-0323.

2. Goldberg, D.; Loughner, C.P.; Tzortziou, M.; Stehr, J.W.; Pickering, K.E.; Marufu, L.T.; Dickerson, R.R. Higher surface ozone concentrations over the Chesapeake Bay than over the adjacent land: Observations and models from the DISCOVER-AQ and CBODAQ campaigns; Atmos. Environ. 2014, 84,https://doi.org/10.1016/j.atmosenv.2013.11.008.

3. Mathur, R.; Hogrefe, C.; Hakami, A.; Zhao, S.; Szykman, J.; Hagler, G. A Call for an Aloft Air Quality Monitoring Network: Need, Feasibility, andPotential Value; Environ. Sci. Technol. 2018, 52, 10903-10908, doi: 10.1021/acs.est.8b02496.

4. Technical Note: Guidance for Developing Enhanced Monitoring Plans; U.S. Environmental Protection Agency, May 2017; https://www.epa.gov/amtic/enhanced-monitoring-plan-guidance (accessed July 14, 2020).

Susan S.G. Wierman, the former Executive Director for the Mid-Atlantic Regional Air Management Association, is a part-time lecturer for theJohns Hopkins University online Engineering for Professionals program. Leiran Biton is a physical scientist with the U.S. Environmental Protec-tion Agency’s New England Regional Office (Region 1) in Boston, MA, and he and Susan Wierman are members of EM’s Editorial AdvisoryCommittee. Joel Dreessen is senior meteorologist in the air monitoring program at the Maryland Department of the Environment.

Disclaimer: This article has been subject to technical review by the U.S. Environmental Protection Agency (EPA) and approved for publication.The views expressed by individual authors, however, are their own, and do not necessarily reflect those of the EPA. Mention of trade names,products, or services does not convey, and should not be interpreted as conveying, official EPA approval, endorsement, or recommendation.

Figure 3. Lake Michigan (June 9, 2017).Lake Michigan stays relatively cold through thesummer, potentially causing lake breezes when-ever the land temperatures warm and synopticwinds are light. On June 9, 2017, a lake breezecan be seen moving inland around nearly the entire lake. Ozone exceedances of the 70 ppbwere measured in the lake breezes, particularlyaround Chicago, into northern Indiana andsouthern Michigan.Source: True color imagery from VIIRS instrument on theSuomi NPP satellite. NOAA JSTAR Mapper(https://www.star.nesdis.noaa.gov/jpss/mapper).

Figure 4. Gulf of Mexico (June 9, 2017).Intricate clouds formed over the Gulf of Mexicoon June 9, 2017, contrast the expansive cloudsfarther inland, demonstrating the different meteorological conditions that overland andoverwater areas experience, and the complexityof these influences at the coastal interface. Source: True color imagery from VIIRS instrument on theSuomi NPP satellite. NOAA JSTAR Mapper(https://www.star.nesdis.noaa.gov/jpss/mapper).

Each of these multi-agency collaborative studies yielded information about micro meteorology, pollution transport,and the impacts of local and distant sources on air qualityabove and near large bodies of water. em