scholarly journals Supplementary material to "Higher measured than modeled ozone production at increased NO<sub><i>x</i></sub> levels in the Colorado Front Range"

2017 ◽  
Author(s):  
Bianca Baier ◽  
William Brune ◽  
David Miller ◽  
Donald Blake ◽  
Russell Long ◽  
...  
Keyword(s):  
Colorado Front Range ◽  
Ozone Production ◽  
Front Range ◽  
Supplementary Material

scholarly journals Chemical Characteristics and Ozone Production in the Northern Colorado Front Range

2019 ◽  
Vol 124 (23) ◽  
pp. 13397-13419
Author(s):  
Gabriele Pfister ◽  
Chi‐Tsan Wang ◽  
Mary Barth ◽  
Frank Flocke ◽  
William Vizuete ◽  
...  
Keyword(s):  
Colorado Front Range ◽  
Ozone Production ◽  
Chemical Characteristics ◽  
Front Range ◽  
Northern Colorado

scholarly journals Supplementary material to "Tropospheric sources and sinks of gas-phase acids in the Colorado Front Range"

2018 ◽  
Author(s):  
James M. Mattila ◽  
Patrick Brophy ◽  
Jeffrey Kirkland ◽  
Samuel Hall ◽  
Kirk Ullmann ◽  
...  
Keyword(s):  
Gas Phase ◽  
Colorado Front Range ◽  
Front Range ◽  
Sources And Sinks ◽  
Supplementary Material

scholarly journals Higher measured than modeled ozone production at increased NO<sub><i>x</i></sub> levels in the Colorado Front Range

2017 ◽  
Author(s):  
Bianca Baier ◽  
William Brune ◽  
David Miller ◽  
Donald Blake ◽  
Russell Long ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Mitigation Strategies ◽  
Peroxyl Radicals ◽  
Chemical Mechanism ◽  
Colorado Front Range ◽  
Ozone Production ◽  
Front Range ◽  
Volatile Organic

Abstract. Chemical models must accurately calculate the ozone formation rate, P(O3), to accurately predict ozone levels and test mitigation strategies. However, model chemical mechanisms can contain large uncertainties in P(O3) calculations, which can create uncertainties in ozone forecasts especially during the summertime when P(O3) can be high. One way to test mechanisms is to evaluate model P(O3) using direct measurements. During summer 2014, the Measurement of Ozone Production Sensor (MOPS) measured net P(O3) in Golden, CO, approximately 25 km west of Denver along the Colorado Front Range. Net P(O3) was compared to rates calculated by a photochemical box model using a lumped and a more explicit chemical mechanism. Observed P(O3) was up to a factor of two higher than that modeled during early morning hours when nitric oxide (NO) levels were high, contrary to traditional ozone chemistry theory. This disagreement may be due to model underestimation of hydroperoxyl (HO2) radicals relative to observations at high NO levels. These additional peroxyl radicals could come from the MOPS chamber chemistry or from missing volatile organic compounds co-emitted with NOx; additional cycling of OH into HO2 through reactions involving nitric oxide provides an alternate explanation for higher measured than modeled P(O3). Although the MOPS measurements are new, comparisons of observed and modeled P(O3) in NO space show a similar behavior to other comparisons between P(O3) derived from measurements and modeled P(O3). These comparisons can have implications for the sensitivity of P(O3) to nitrogen oxides and volatile organic compounds during morning hours, and can possibly affect ozone reduction strategies for the region surrounding Golden, CO in addition to other urban and suburban areas that are in non-attainment with national ozone regulations.

scholarly journals Using TES retrievals to investigate PAN in North American biomass burning plumes

2018 ◽  
Vol 18 (8) ◽  
pp. 5639-5653 ◽  
Author(s):  
Emily V. Fischer ◽  
Liye Zhu ◽  
Vivienne H. Payne ◽  
John R. Worden ◽  
Zhe Jiang ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Colorado Front Range ◽  
Ozone Production ◽  
Hazard Mapping ◽  
Front Range ◽  
Mapping System ◽  
Smoke Plumes ◽  
In Situ Observations

Abstract. Peroxyacyl nitrate (PAN) is a critical atmospheric reservoir for nitrogen oxide radicals, and plays a lead role in their redistribution in the troposphere. We analyze new Tropospheric Emission Spectrometer (TES) PAN observations over North America from July 2006 to July 2009. Using aircraft observations from the Colorado Front Range, we demonstrate that TES can be sensitive to elevated PAN in the boundary layer (∼ 750 hPa) even in the presence of clouds. In situ observations have shown that wildfire emissions can rapidly produce PAN, and PAN decomposition is an important component of ozone production in smoke plumes. We identify smoke-impacted TES PAN retrievals by co-location with NOAA Hazard Mapping System (HMS) smoke plumes. Depending on the year, 15–32 % of cases where elevated PAN is identified in TES observations (retrievals with degrees of freedom (DOF) > 0.6) overlap smoke plumes during July. Of all the retrievals attempted in the July 2006 to July 2009 study period, 18 % is associated with smoke . A case study of smoke transport in July 2007 illustrates that PAN enhancements associated with HMS smoke plumes can be connected to fire complexes, providing evidence that TES is sufficiently sensitive to measure elevated PAN several days downwind of major fires. Using a subset of retrievals with TES 510 hPa carbon monoxide (CO) > 150 ppbv, and multiple estimates of background PAN, we calculate enhancement ratios for tropospheric average PAN relative to CO in smoke-impacted retrievals. Most of the TES-based enhancement ratios fall within the range calculated from in situ measurements.

scholarly journals The Contribution of Fires to TES Observations of Free Tropospheric PAN over North America in July

2017 ◽  
Author(s):  
Emily V. Fischer ◽  
Liye Zhu ◽  
Vivienne H. Payne ◽  
John R. Worden ◽  
Zhe Jiang ◽  
...  
Keyword(s):  
North America ◽  
Colorado Front Range ◽  
Ozone Production ◽  
Hazard Mapping ◽  
Front Range ◽  
Mapping System ◽  
Smoke Plumes ◽  
In Situ Observations

Abstract. Peroxyacetyl nitrate (PAN) is a critical atmospheric reservoir for nitrogen oxide radicals, and it plays a lead role in their redistribution in the troposphere. We analyze new Tropospheric Emission Spectrometer (TES) PAN observations over North America during July 2006 to 2009. Using aircraft observations from the Colorado Front Range, we demonstrate that TES can be sensitive to elevated PAN in the boundary layer even in the presence of clouds. In situ observations have shown that wildfire emissions can rapidly produce PAN, and PAN decomposition is an important component of ozone production in smoke plumes. We identify smoke-impacted TES PAN retrievals by co-location with NOAA Hazard Mapping System (HMS) smoke plumes. We find that 15–32 % of cases where elevated PAN is identified in TES observations (retrievals with DOF > 0.6) overlap smoke plumes. A case study of smoke transport in July 2007 illustrates that PAN enhancements associated with HMS smoke plumes can be connected to fire complexes, providing evidence that TES is sufficiently sensitive to measure elevated PAN several days downwind of major fires. Using a subset of retrievals with TES 510 hPa carbon monoxide (CO) > 150 ppbv, and multiple estimates of background PAN, we calculate enhancement ratios for tropospheric average PAN relative to CO in smoke-impacted retrievals. Most of the TES-based enhancement ratios fall within the range calculated from in situ measurements.

scholarly journals Higher measured than modeled ozone production at increased NO<sub><i>x</i></sub> levels in the Colorado Front Range

2017 ◽  
Vol 17 (18) ◽  
pp. 11273-11292 ◽  
Author(s):  
Bianca C. Baier ◽  
William H. Brune ◽  
David O. Miller ◽  
Donald Blake ◽  
Russell Long ◽  
...  
Keyword(s):  
Formation Rate ◽  
Chemical Species ◽  
Peroxy Radical ◽  
Early Morning ◽  
Mitigation Strategies ◽  
Chemical Mechanism ◽  
Colorado Front Range ◽  
Ozone Production ◽  
Front Range ◽  
Reduction Strategies

Abstract. Chemical models must correctly calculate the ozone formation rate, P(O3), to accurately predict ozone levels and to test mitigation strategies. However, air quality models can have large uncertainties in P(O3) calculations, which can create uncertainties in ozone forecasts, especially during the summertime when P(O3) is high. One way to test mechanisms is to compare modeled P(O3) to direct measurements. During summer 2014, the Measurement of Ozone Production Sensor (MOPS) directly measured net P(O3) in Golden, CO, approximately 25 km west of Denver along the Colorado Front Range. Net P(O3) was compared to rates calculated by a photochemical box model that was constrained by measurements of other chemical species and that used a lumped chemical mechanism and a more explicit one. Median observed P(O3) was up to a factor of 2 higher than that modeled during early morning hours when nitric oxide (NO) levels were high and was similar to modeled P(O3) for the rest of the day. While all interferences and offsets in this new method are not fully understood, simulations of these possible uncertainties cannot explain the observed P(O3) behavior. Modeled and measured P(O3) and peroxy radical (HO2 and RO2) discrepancies observed here are similar to those presented in prior studies. While a missing atmospheric organic peroxy radical source from volatile organic compounds co-emitted with NO could be one plausible solution to the P(O3) discrepancy, such a source has not been identified and does not fully explain the peroxy radical model–data mismatch. If the MOPS accurately depicts atmospheric P(O3), then these results would imply that P(O3) in Golden, CO, would be NOx-sensitive for more of the day than what is calculated by models, extending the NOx-sensitive P(O3) regime from the afternoon further into the morning. These results could affect ozone reduction strategies for the region surrounding Golden and possibly other areas that do not comply with national ozone regulations. Thus, it is important to continue the development of this direct ozone measurement technique to understand P(O3), especially under high-NOx regimes.

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