Strong wintertime ozone events in the Upper Green River basin, Wyoming

B. Rappenglück, Luis Ackermann, S. Alvarez, J. Golovko, M. Buhr, R. A. Field, J. Soltis, D. C. Montague, B. Hauze, S. Adamson, D. Risch, G. Wilkerson, D. Bush, T. Stoeckenius, C. Keslar

Research output: Contribution to journalArticle

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Abstract

During recent years, elevated ozone (O<inf>3</inf>) values have been observed repeatedly in the Upper Green River basin (UGRB), Wyoming, during wintertime. This paper presents an analysis of high ozone days in late winter 2011 (1 h average up to 166 ppbv - parts per billion by volume). Intensive operational periods (IOPs) of ambient monitoring were performed, which included comprehensive surface and boundary layer measurements. On IOP days, maximum O<inf>3</inf> values are restricted to a very shallow surface layer. Low wind speeds in combination with low mixing layer heights (∼ 50 m above ground level around noontime) are essential for accumulation of pollutants within the UGRB. Air masses contain substantial amounts of reactive nitrogen (NO<inf>x</inf>) and non-methane hydrocarbons (NMHC) emitted from fossil fuel exploration activities in the Pinedale Anticline. On IOP days particularly in the morning hours, reactive nitrogen (up to 69%), aromatics and alkanes (∼ 10-15%; mostly ethane and propane) are major contributors to the hydroxyl (OH) reactivity. Measurements at the Boulder monitoring site during these time periods under SW wind flow conditions show the lowest NMHC / NO<inf>x</inf> ratios (∼ 50), reflecting a relatively low reactive NMHC mixture, and a change from a NO<inf>x</inf>-limited regime towards a NMHC-limited regime as indicated by photochemical indicators, e.g., O<inf>3</inf>/NOy, O<inf>3</inf>/NOz, and O<inf>3</inf> / HNO<inf>3</inf> and the EOR (extent of reaction). OH production on IOP days is mainly due to nitrous acid (HONO). On a 24 h basis and as determined for a measurement height of 1.80 m above the surface HONO photolysis on IOP days can contribute ∼ 83% to OH production on average, followed by alkene ozonolysis (∼ 9%). Photolysis by ozone and HCHO photolysis contribute about 4% each to hydroxyl formation. High HONO levels (maximum hourly median on IOP days: 1096 pptv - parts per trillion by volume) are favored by a combination of shallow boundary layer conditions and enhanced photolysis rates due to the high albedo of the snow surface. HONO is most likely formed through (i) abundant nitric acid (HNO<inf>3</inf>) produced in atmospheric oxidation of NO<inf>x</inf>, deposited onto the snow surface and undergoing photo-enhanced heterogeneous conversion to HONO (estimated HONO production: 10.2 ± 40% ppbv h<sup>-1</sup>) and (ii) combustion-related emission of HONO (estimated HONO production: ∼ 0.1 ± 30% ppbv h<sup>-1</sup>). HONO production is confined to the lowermost 10 m of the boundary layer. HONO, serves as the most important precursor for OH, strongly enhanced due to the high albedo of the snow cover (HONO photolysis rate 10.7 ± 30% ppbv h<sup>-1</sup>). OH radicals will oxidize NMHCs, mostly aromatics (toluene, xylenes) and alkanes (ethane, propane), eventually leading to an increase in ozone.

Original languageEnglish
Pages (from-to)4909-4934
Number of pages26
JournalAtmospheric Chemistry and Physics
Volume14
Issue number10
DOIs
Publication statusPublished - 20 May 2014
Externally publishedYes

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photolysis
nonmethane hydrocarbon
river basin
ozone
boundary layer
propane
ethane
alkane
albedo
surface layer
snow
alkene
nitrogen
xylene
monitoring
boulder
nitric acid
anticline
snow cover
toluene

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Rappenglück, B., Ackermann, L., Alvarez, S., Golovko, J., Buhr, M., Field, R. A., ... Keslar, C. (2014). Strong wintertime ozone events in the Upper Green River basin, Wyoming. Atmospheric Chemistry and Physics, 14(10), 4909-4934. https://doi.org/10.5194/acp-14-4909-2014

Strong wintertime ozone events in the Upper Green River basin, Wyoming. / Rappenglück, B.; Ackermann, Luis; Alvarez, S.; Golovko, J.; Buhr, M.; Field, R. A.; Soltis, J.; Montague, D. C.; Hauze, B.; Adamson, S.; Risch, D.; Wilkerson, G.; Bush, D.; Stoeckenius, T.; Keslar, C.

In: Atmospheric Chemistry and Physics, Vol. 14, No. 10, 20.05.2014, p. 4909-4934.

Research output: Contribution to journalArticle

Rappenglück, B, Ackermann, L, Alvarez, S, Golovko, J, Buhr, M, Field, RA, Soltis, J, Montague, DC, Hauze, B, Adamson, S, Risch, D, Wilkerson, G, Bush, D, Stoeckenius, T & Keslar, C 2014, 'Strong wintertime ozone events in the Upper Green River basin, Wyoming', Atmospheric Chemistry and Physics, vol. 14, no. 10, pp. 4909-4934. https://doi.org/10.5194/acp-14-4909-2014
Rappenglück, B. ; Ackermann, Luis ; Alvarez, S. ; Golovko, J. ; Buhr, M. ; Field, R. A. ; Soltis, J. ; Montague, D. C. ; Hauze, B. ; Adamson, S. ; Risch, D. ; Wilkerson, G. ; Bush, D. ; Stoeckenius, T. ; Keslar, C. / Strong wintertime ozone events in the Upper Green River basin, Wyoming. In: Atmospheric Chemistry and Physics. 2014 ; Vol. 14, No. 10. pp. 4909-4934.
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abstract = "During recent years, elevated ozone (O3) values have been observed repeatedly in the Upper Green River basin (UGRB), Wyoming, during wintertime. This paper presents an analysis of high ozone days in late winter 2011 (1 h average up to 166 ppbv - parts per billion by volume). Intensive operational periods (IOPs) of ambient monitoring were performed, which included comprehensive surface and boundary layer measurements. On IOP days, maximum O3 values are restricted to a very shallow surface layer. Low wind speeds in combination with low mixing layer heights (∼ 50 m above ground level around noontime) are essential for accumulation of pollutants within the UGRB. Air masses contain substantial amounts of reactive nitrogen (NOx) and non-methane hydrocarbons (NMHC) emitted from fossil fuel exploration activities in the Pinedale Anticline. On IOP days particularly in the morning hours, reactive nitrogen (up to 69{\%}), aromatics and alkanes (∼ 10-15{\%}; mostly ethane and propane) are major contributors to the hydroxyl (OH) reactivity. Measurements at the Boulder monitoring site during these time periods under SW wind flow conditions show the lowest NMHC / NOx ratios (∼ 50), reflecting a relatively low reactive NMHC mixture, and a change from a NOx-limited regime towards a NMHC-limited regime as indicated by photochemical indicators, e.g., O3/NOy, O3/NOz, and O3 / HNO3 and the EOR (extent of reaction). OH production on IOP days is mainly due to nitrous acid (HONO). On a 24 h basis and as determined for a measurement height of 1.80 m above the surface HONO photolysis on IOP days can contribute ∼ 83{\%} to OH production on average, followed by alkene ozonolysis (∼ 9{\%}). Photolysis by ozone and HCHO photolysis contribute about 4{\%} each to hydroxyl formation. High HONO levels (maximum hourly median on IOP days: 1096 pptv - parts per trillion by volume) are favored by a combination of shallow boundary layer conditions and enhanced photolysis rates due to the high albedo of the snow surface. HONO is most likely formed through (i) abundant nitric acid (HNO3) produced in atmospheric oxidation of NOx, deposited onto the snow surface and undergoing photo-enhanced heterogeneous conversion to HONO (estimated HONO production: 10.2 ± 40{\%} ppbv h-1) and (ii) combustion-related emission of HONO (estimated HONO production: ∼ 0.1 ± 30{\%} ppbv h-1). HONO production is confined to the lowermost 10 m of the boundary layer. HONO, serves as the most important precursor for OH, strongly enhanced due to the high albedo of the snow cover (HONO photolysis rate 10.7 ± 30{\%} ppbv h-1). OH radicals will oxidize NMHCs, mostly aromatics (toluene, xylenes) and alkanes (ethane, propane), eventually leading to an increase in ozone.",
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T1 - Strong wintertime ozone events in the Upper Green River basin, Wyoming

AU - Rappenglück, B.

AU - Ackermann, Luis

AU - Alvarez, S.

AU - Golovko, J.

AU - Buhr, M.

AU - Field, R. A.

AU - Soltis, J.

AU - Montague, D. C.

AU - Hauze, B.

AU - Adamson, S.

AU - Risch, D.

AU - Wilkerson, G.

AU - Bush, D.

AU - Stoeckenius, T.

AU - Keslar, C.

PY - 2014/5/20

Y1 - 2014/5/20

N2 - During recent years, elevated ozone (O3) values have been observed repeatedly in the Upper Green River basin (UGRB), Wyoming, during wintertime. This paper presents an analysis of high ozone days in late winter 2011 (1 h average up to 166 ppbv - parts per billion by volume). Intensive operational periods (IOPs) of ambient monitoring were performed, which included comprehensive surface and boundary layer measurements. On IOP days, maximum O3 values are restricted to a very shallow surface layer. Low wind speeds in combination with low mixing layer heights (∼ 50 m above ground level around noontime) are essential for accumulation of pollutants within the UGRB. Air masses contain substantial amounts of reactive nitrogen (NOx) and non-methane hydrocarbons (NMHC) emitted from fossil fuel exploration activities in the Pinedale Anticline. On IOP days particularly in the morning hours, reactive nitrogen (up to 69%), aromatics and alkanes (∼ 10-15%; mostly ethane and propane) are major contributors to the hydroxyl (OH) reactivity. Measurements at the Boulder monitoring site during these time periods under SW wind flow conditions show the lowest NMHC / NOx ratios (∼ 50), reflecting a relatively low reactive NMHC mixture, and a change from a NOx-limited regime towards a NMHC-limited regime as indicated by photochemical indicators, e.g., O3/NOy, O3/NOz, and O3 / HNO3 and the EOR (extent of reaction). OH production on IOP days is mainly due to nitrous acid (HONO). On a 24 h basis and as determined for a measurement height of 1.80 m above the surface HONO photolysis on IOP days can contribute ∼ 83% to OH production on average, followed by alkene ozonolysis (∼ 9%). Photolysis by ozone and HCHO photolysis contribute about 4% each to hydroxyl formation. High HONO levels (maximum hourly median on IOP days: 1096 pptv - parts per trillion by volume) are favored by a combination of shallow boundary layer conditions and enhanced photolysis rates due to the high albedo of the snow surface. HONO is most likely formed through (i) abundant nitric acid (HNO3) produced in atmospheric oxidation of NOx, deposited onto the snow surface and undergoing photo-enhanced heterogeneous conversion to HONO (estimated HONO production: 10.2 ± 40% ppbv h-1) and (ii) combustion-related emission of HONO (estimated HONO production: ∼ 0.1 ± 30% ppbv h-1). HONO production is confined to the lowermost 10 m of the boundary layer. HONO, serves as the most important precursor for OH, strongly enhanced due to the high albedo of the snow cover (HONO photolysis rate 10.7 ± 30% ppbv h-1). OH radicals will oxidize NMHCs, mostly aromatics (toluene, xylenes) and alkanes (ethane, propane), eventually leading to an increase in ozone.

AB - During recent years, elevated ozone (O3) values have been observed repeatedly in the Upper Green River basin (UGRB), Wyoming, during wintertime. This paper presents an analysis of high ozone days in late winter 2011 (1 h average up to 166 ppbv - parts per billion by volume). Intensive operational periods (IOPs) of ambient monitoring were performed, which included comprehensive surface and boundary layer measurements. On IOP days, maximum O3 values are restricted to a very shallow surface layer. Low wind speeds in combination with low mixing layer heights (∼ 50 m above ground level around noontime) are essential for accumulation of pollutants within the UGRB. Air masses contain substantial amounts of reactive nitrogen (NOx) and non-methane hydrocarbons (NMHC) emitted from fossil fuel exploration activities in the Pinedale Anticline. On IOP days particularly in the morning hours, reactive nitrogen (up to 69%), aromatics and alkanes (∼ 10-15%; mostly ethane and propane) are major contributors to the hydroxyl (OH) reactivity. Measurements at the Boulder monitoring site during these time periods under SW wind flow conditions show the lowest NMHC / NOx ratios (∼ 50), reflecting a relatively low reactive NMHC mixture, and a change from a NOx-limited regime towards a NMHC-limited regime as indicated by photochemical indicators, e.g., O3/NOy, O3/NOz, and O3 / HNO3 and the EOR (extent of reaction). OH production on IOP days is mainly due to nitrous acid (HONO). On a 24 h basis and as determined for a measurement height of 1.80 m above the surface HONO photolysis on IOP days can contribute ∼ 83% to OH production on average, followed by alkene ozonolysis (∼ 9%). Photolysis by ozone and HCHO photolysis contribute about 4% each to hydroxyl formation. High HONO levels (maximum hourly median on IOP days: 1096 pptv - parts per trillion by volume) are favored by a combination of shallow boundary layer conditions and enhanced photolysis rates due to the high albedo of the snow surface. HONO is most likely formed through (i) abundant nitric acid (HNO3) produced in atmospheric oxidation of NOx, deposited onto the snow surface and undergoing photo-enhanced heterogeneous conversion to HONO (estimated HONO production: 10.2 ± 40% ppbv h-1) and (ii) combustion-related emission of HONO (estimated HONO production: ∼ 0.1 ± 30% ppbv h-1). HONO production is confined to the lowermost 10 m of the boundary layer. HONO, serves as the most important precursor for OH, strongly enhanced due to the high albedo of the snow cover (HONO photolysis rate 10.7 ± 30% ppbv h-1). OH radicals will oxidize NMHCs, mostly aromatics (toluene, xylenes) and alkanes (ethane, propane), eventually leading to an increase in ozone.

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