The Role of Temperature and NO<i><sub>x</sub></i> in Ozone Trends in the Los Angeles Basin

Nussbaumer, Clara M.; Cohen, R. C.

doi:10.1021/acs.est.0c04910

Cited by 63 publications

(76 citation statements)

References 22 publications

(59 reference statements)

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“…The profiles are calculated with respect to the center of the particular bin, e.g., the average at 3.5 km includes all data points obtained at or above 3 km altitude and below 4 km altitude. Data are filtered for stratospheric influence by removing all data points for which concurrent O 3 concentration is larger than 100 ppbv; this is a conservative criterion which has been discussed by Prather et al (2011). The vertical profile of measured NO data shows lowest NO mixing ratios of less than 20 pptv observed between 2 and 8 km altitude, which reflect the absence of emission and transport sources at these altitudes.…”

Section: Vertical Profiles Of No and O 3 In The Tropical Tropospherementioning

confidence: 99%

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and western Africa

Tadić

Nussbaumer

Bohn³

et al. 2021

Atmos. Chem. Phys.

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Abstract. Mechanisms of tropospheric ozone (O3) formation are generally well understood. However, studies reporting on net ozone production rates (NOPRs) directly derived from in situ observations are challenging and are sparse in number. To analyze the role of nitric oxide (NO) in net ozone production in the upper tropical troposphere above the Atlantic Ocean and western Africa, we present in situ trace gas observations obtained during the CAFE-Africa (Chemistry of the Atmosphere: Field Experiment in Africa) campaign in August and September 2018. The vertical profile of in situ measured NO along the flight tracks reveals lowest NO mixing ratios of less than 20 pptv between 2 and 8 km altitude and highest mixing ratios of 0.15–0.2 ppbv above 12 km altitude. Spatial distribution of tropospheric NO above 12 km altitude shows that the sporadically enhanced local mixing ratios (>0.4 ppbv) occur over western Africa, which we attribute to episodic lightning events. Measured O3 shows little variability in mixing ratios at 60–70 ppbv, with slightly decreasing and increasing tendencies towards the boundary layer and stratosphere, respectively. Concurrent measurements of CO, CH4, OH, HO2 and H2O enable calculations of NOPRs along the flight tracks and reveal net ozone destruction at −0.6 to −0.2 ppbv h−1 below 6 km altitude and balance of production and destruction around 7–8 km altitude. We report vertical average NOPRs of 0.2–0.4 ppbv h−1 above 12 km altitude with NOPRs occasionally larger than 0.5 ppbv h−1 over western Africa coincident with enhanced NO. We compare the observational results to simulated data retrieved from the general circulation model ECHAM/MESSy Atmospheric Chemistry (EMAC). Although the comparison of mean vertical profiles of NO and O3 indicates good agreement, local deviations between measured and modeled NO are substantial. The vertical tendencies in NOPRs calculated from simulated data largely reproduce those from in situ experimental data. However, the simulation results do not agree well with NOPRs over western Africa. Both measurements and simulations indicate that ozone formation in the upper tropical troposphere is NOx limited.

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Section: Vertical Profiles Of No and O 3 In The Tropical Tropospherementioning

confidence: 99%

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and western Africa

Tadić

Nussbaumer

Bohn³

et al. 2021

Atmos. Chem. Phys.

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“…In the US, ambient ozone was designated a criteria air pollutant already in the 1970s (Jaffe et al, 2018). Since then and especially in the last decades, increasing effort has been put in the understanding and mitigation of tropospheric ozone pollution (Fiore et al, 2002;Dentener et al, 2005;West and Fiore, 2005;Lelieveld et al, 2009, Pusede et al, 2015Jaffe et al, 2018;Nussbaumer and Cohen, 2020;Tadic et al, 2020). To further resolve the complexity of scientific and policy-related issues of the NOx-O3-VOCs relationship, careful evaluation of model simulations against in situ measurement data is required (Sillman et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

“…Ozone formation hence crucially depends on whether NOx or VOCs are available in excess. These two atmospheric states are commonly referred to as either VOC-limited (if NOx is available in excess) or as NOx-limited (if VOCs are available in excess) (Duncan et al, 2010;Nussbaumer and Cohen, 2020;Tadic et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and West Africa

Tadić¹,

Nussbaumer²,

Bohn³

et al. 2021

Preprint

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Abstract. Mechanisms of tropospheric ozone (O3) formation are generally well understood. However, studies reporting on net ozone production rates (NOPRs) directly derived from in-situ observations are challenging, and are sparse in number. To analyze the role of nitric oxide (NO) in net ozone production in the upper tropical troposphere above the Atlantic Ocean and the West African continent, we present in situ trace gas observations obtained during the CAFE-Africa (Chemistry of the Atmosphere: Field Experiment in Africa) campaign in August and September 2018. The vertical profile of in situ measured NO along the flight tracks reveals lowest NO mixing ratios of less than 20 pptv between 2 and 8 km altitude and highest mixing ratios of 0.15–0.2 ppbv above 12 km altitude. Spatial distribution of tropospheric NO above 12 km altitude shows that the sporadically enhanced local mixing ratios (> 0.4 ppbv) occur over the West African continent, which we attribute to episodic lightning events. Measured O3 shows little variability in mixing ratios at 60–70 ppbv, with slightly decreasing and increasing tendencies towards the boundary layer and stratosphere, respectively. Concurrent measurements of CO, CH4, OH and HO2 and H2O enable calculations of NOPRs along the flight tracks and reveal net ozone destruction at −0.6 to −0.2 ppbv h−1 below 6 km altitude and balance of production and destruction around 7–8 km altitude. We report vertical average NOPRs of 0.2–0.4 ppbv h−1 above 12 km altitude with NOPRs occasionally larger than 0.5 ppbv h−1 over West Africa coincident with enhanced NO. We compare the observational results to simulated data retrieved from the general circulation ECHAM/MESSy Atmospheric Chemistry (EMAC) model. Although the comparison of mean vertical profiles of NO and O3 indicates good agreement, local deviations between measured and modelled NO are substantial. The vertical tendencies in NOPRs calculated from simulated data largely reproduce those from in situ experimental data. However, the simulation results do not agree well with NOPRs over the West African continent. Both measurements and simulations indicate that ozone formation in the upper tropical troposphere is NOx-limited.

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“…Over the ocean, the only significant NO emissions are from lightning, ships and aircraft (Bond et al, 2002;Masiol and Harrison, 2014). NO sources over land are more versatile including anthropogenic emissions from industry, vehicles and biomass burning (partly natural) as well as natural sources from lightning and soil, with the natural sources dominating over West Africa (Pacifico et al, 2019;Knippertz et al, 2015). One lightning flash produces approximately (2-40) × 10 25 molecules of NO, which together with NO 2 as NO x have a lifetime of several days near the Equator (Pollack et al, 2016;Schumann and Huntrieser, 2007;Levy et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018

et al. 2021

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Abstract. Hurricane Florence was the sixth named storm in the Atlantic hurricane season 2018. It caused dozens of deaths and major economic damage. In this study, we present in situ observations of trace gases within tropical storm Florence on 2 September 2018, after it had developed a rotating nature, and of a tropical wave observed close to the African continent on 29 August 2018 as part of the research campaign CAFE Africa (Chemistry of the Atmosphere: Field Experiment in Africa) with HALO (High Altitude and LOng Range Research Aircraft). We show the impact of deep convection on atmospheric composition by measurements of the trace gases nitric oxide (NO), ozone (O3), carbon monoxide (CO), hydrogen peroxide (H2O2), dimethyl sulfide (DMS) and methyl iodide (CH3I) and by the help of color-enhanced infrared satellite imagery taken by GOES-16. While both systems, i.e., the tropical wave and the tropical storm, are deeply convective, we only find evidence for lightning in the tropical wave using both in situ NO measurements and data from the World Wide Lightning Location Network (WWLLN).

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The Role of Temperature and NO_x in Ozone Trends in the Los Angeles Basin

Cited by 63 publications

References 22 publications

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and western Africa

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and western Africa

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and West Africa

Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018

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The Role of Temperature and NOx in Ozone Trends in the Los Angeles Basin

Cited by 63 publications

References 22 publications

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and western Africa

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and western Africa

Central role of nitric oxide in ozone production in the upper tropical troposphere over the Atlantic Ocean and West Africa

Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018

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The Role of Temperature and NO_x in Ozone Trends in the Los Angeles Basin