Polar Nighttime Chemistry Produces Intense Reactive Bromine Events

Abstract. High wintertime ozone levels have been observed in the Uintah Basin, Utah, a sparsely populated rural region with intensive oil and gas operations. The reactive nitrogen budget plays an important role in tropospheric ozone formation. Measurements were taken during three field campaigns in the winters of 2012, 2013 and 2014, which experienced varying climatic conditions. Average concentrations of ozone and total reactive nitrogen were observed to be 2.5 times higher in 2013 than 2012, with 2014 an intermediate year in most respects. However, photochemically active NOx (NO + NO2) remained remarkably similar all three years. Nitric acid comprised roughly half of NOz ( ≡  NOy − NOx) in 2013, with nighttime nitric acid formation through heterogeneous uptake of N2O5 contributing approximately 6 times more than daytime formation. In 2012, N2O5 and ClNO2 were larger components of NOz relative to HNO3. The nighttime N2O5 lifetime between the high-ozone year 2013 and the low-ozone year 2012 is lower by a factor of 2.6, and much of this is due to higher aerosol surface area in the high-ozone year of 2013. A box-model simulation supports the importance of nighttime chemistry on the reactive nitrogen budget, showing a large sensitivity of NOx and ozone concentrations to nighttime processes.

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A modeling study of the nighttime radical chemistry in the lower continental troposphere: 1. Development of a detailed chemical mechanism including nighttime chemistry

Journal of Geophysical Research Atmospheres ◽

10.1029/2000jd900347 ◽

2001 ◽

Vol 106 (D9) ◽

pp. 9959-9990 ◽

Cited By ~ 22

Author(s):

Isabelle Bey ◽

Bernard Aumont ◽

Gérard Toupance

Keyword(s):

Chemical Mechanism ◽

Radical Chemistry ◽

Nighttime Chemistry ◽

Detailed Chemical ◽

Modeling Study

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Variable lifetimes and loss mechanisms for NO3 and N2O5 during the DOMINO campaign: contrasts between marine, urban and continental air

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-17825-2011 ◽

2011 ◽

Vol 11 (6) ◽

pp. 17825-17877

Author(s):

J. N. Crowley ◽

J. Thieser ◽

M. Tang ◽

G. Schuster ◽

H. Bozem ◽

...

Keyword(s):

Gas Phase ◽

High Reactivity ◽

Heterogeneous Reactions ◽

Urban Air ◽

Industrial Complex ◽

Atlantic Sector ◽

Air Masses ◽

Mixing Ratios ◽

Nighttime Chemistry ◽

Heterogeneous Processes

Abstract. Nighttime mixing ratios of boundary layer N2O5 were determined using cavity-ring-down spectroscopy during the DOMINO campaign. Observation of N2O5 was intermittent, with mixing ratios ranging from below the detection limit (~5 ppt) to ~500 ppt. A steady-state analysis constrained by measured mixing ratios of NO2 and O3 was used to derive NO3 lifetimes and compare them to calculated rates of loss via gas-phase and heterogeneous reactions of both NO3 and N2O5. Three distinct types of air masses were encountered, which were largely marine (Atlantic), continental or urban-industrial in origin. NO3 lifetimes were longest in the Atlantic sector (up to ~30 min) but were very short (a few seconds) in polluted, air masses from the local city and petroleum-related industrial complex of Huelva. Air from the continental sector was an intermediate case. The high reactivity to NO3 of the urban air mass was not accounted for by gas-phase and heterogeneous reactions, rates of which were constrained by measurements of NO, volatile organic species and aerosol surface area. In general, high NO2 mixing ratios resulted in low NO3 lifetimes, though heterogeneous processes (e.g. reaction of N2O5 on aerosol) were generally less important than direct gas-phase losses of NO3. The presence of SO2 at levels above ~2 ppb in the urban air sector was always associated with very low N2O5 mixing ratios indicating either very short NO3 lifetimes in the presence of combustion-related emissions or an important role for reduced sulphur species in urban, nighttime chemistry. High production rates coupled with low lifetimes of NO3 imply an important contribution of nighttime chemistry to removal of both NOx and VOC.

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