scholarly journals Measurement report: Photochemical production and loss rates of formaldehyde and ozone across Europe

2021 ◽  
Vol 21 (24) ◽  
pp. 18413-18432
Author(s):  
Clara M. Nussbaumer ◽  
John N. Crowley ◽  
Jan Schuladen ◽  
Jonathan Williams ◽  
Sascha Hafermann ◽  
...  
Keyword(s):  
Trace Gases ◽  
Ozone Production ◽  
Trace Gas ◽  
Coastal Site ◽  
Sources And Sinks ◽  
Oxidation Of Methane ◽  
Volatile Organic ◽  
Mountain Site ◽  
In Situ Observations

Abstract. Various atmospheric sources and sinks regulate the abundance of tropospheric formaldehyde (HCHO), which is an important trace gas impacting the HOx (≡ HO2 + OH) budget and the concentration of ozone (O3). In this study, we present the formation and destruction terms of ambient HCHO and O3 calculated from in situ observations of various atmospheric trace gases measured at three different sites across Europe during summertime. These include a coastal site in Cyprus, in the scope of the Cyprus Photochemistry Experiment (CYPHEX) in 2014, a mountain site in southern Germany, as part of the Hohenpeißenberg Photochemistry Experiment (HOPE) in 2012, and a forested site in Finland, where measurements were performed during the Hyytiälä United Measurements of Photochemistry and Particles (HUMPPA) campaign in 2010. We show that, at all three sites, formaldehyde production from the OH oxidation of methane (CH4), acetaldehyde (CH3CHO), isoprene (C5H8) and methanol (CH3OH) can almost completely balance the observed loss via photolysis, OH oxidation and dry deposition. Ozone chemistry is clearly controlled by nitrogen oxides (NOx ≡ NO + NO2) that include O3 production from NO2 photolysis and O3 loss via the reaction with NO. Finally, we use the HCHO budget calculations to determine whether net ozone production is limited by the availability of VOCs (volatile organic compounds; VOC-limited regime) or NOx (NOx-limited regime). At the mountain site in Germany, O3 production is VOC limited, whereas it is NOx limited at the coastal site in Cyprus. The forested site in Finland is in the transition regime.

scholarly journals Measurement report: Photochemical production and loss rates of formaldehyde and ozone across Europe

2021 ◽  
Author(s):  
Clara M. Nussbaumer ◽  
John N. Crowley ◽  
Jan Schuladen ◽  
Jonathan Williams ◽  
Sascha Hafermann ◽  
...  
Keyword(s):  
Trace Gases ◽  
Ozone Production ◽  
Trace Gas ◽  
Coastal Site ◽  
Sources And Sinks ◽  
Oxidation Of Methane ◽  
Mountain Site ◽  
In Situ Observations ◽  
Summer Time

Abstract. Various atmospheric sources and sinks regulate the abundance of tropospheric formaldehyde (HCHO) which is an important trace gas impacting the HOx (≡ HO2 + OH) budget and the concentration of ozone (O3). In this study, we present the formation and destruction terms of ambient HCHO and O3 calculated from in-situ observations of various atmospheric trace gases measured at three different sites across Europe during summer time. These include a coastal site in Cyprus in the scope of the Cyprus Photochemistry Experiment (CYPHEX) in 2014, a mountain site in Southern Germany as part of the Hohenpeißenberg Photochemistry Experiment (HOPE) in 2012 and a forested site in Finland where measurements were performed during the Hyytiälä United Measurements of Photochemistry and Particles (HUMPPA) campaign in 2010. We show that at all three sites formaldehyde production from the OH oxidation of methane (CH4), acetaldehyde (CH3CHO), isoprene (C5H8) and methanol (CH3OH) can almost completely balance the observed loss via photolysis, OH oxidation and dry deposition. Ozone chemistry is clearly controlled by nitrogen oxides (NOx ≡ NO + NO2) that includes O3 production from NO2 photolysis and O3 loss via the reaction with NO. Finally, we use the HCHO budget calculations to determine whether net ozone production is limited by the availability of VOCs (VOC limited regime) or NOx (NOx limited regime). At the mountain site in Germany O3 production is VOC limited, whereas it is NOx limited at the coastal site in Cyprus. The forested site in Finland is in the transition regime.

scholarly journals Characterization of ozone production in San Antonio, Texas, using measurements of total peroxy radicals

2019 ◽  
Vol 19 (5) ◽  
pp. 2845-2860 ◽  
Author(s):  
Daniel C. Anderson ◽  
Jessica Pavelec ◽  
Conner Daube ◽  
Scott C. Herndon ◽  
Walter B. Knighton ◽  
...  
Keyword(s):  
San Antonio ◽  
Peroxy Radical ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Entire Region ◽  
Volatile Organic ◽  
In Situ Observations ◽  
Study Sites

Abstract. Observations of total peroxy radical concentrations ([XO2] ≡ [RO2] + [HO2]) made by the Ethane CHemical AMPlifier (ECHAMP) and concomitant observations of additional trace gases made on board the Aerodyne Mobile Laboratory (AML) during May 2017 were used to characterize ozone production at three sites in the San Antonio, Texas, region. Median daytime [O3] was 48 ppbv at the site downwind of central San Antonio. Higher concentrations of NO and XO2 at the downwind site also led to median daytime ozone production rates (P(O3)) of 4.2 ppbv h−1, a factor of 2 higher than at the two upwind sites. The 95th percentile of P(O3) at the upwind site was 15.1 ppbv h−1, significantly lower than values observed in Houston. In situ observations, as well as satellite retrievals of HCHO and NO2, suggest that the region was predominantly NOx-limited. Only approximately 20 % of observations were in the VOC-limited regime, predominantly before 11:00 EST, when ozone production was low. Biogenic volatile organic compounds (VOCs) comprised 55 % of total OH reactivity at the downwind site, with alkanes and non-biogenic alkenes responsible for less than 10 % of total OH reactivity in the afternoon, when ozone production was highest. To control ozone formation rates at the three study sites effectively, policy efforts should be directed at reducing NOx emissions. Observations in the urban center of San Antonio are needed to determine whether this policy is true for the entire region.

scholarly journals Characterization of Ozone Production in San Antonio, Texas Using Observations of Total Peroxy Radicals

2018 ◽  
Author(s):  
Daniel C. Anderson ◽  
Jessica Pavelec ◽  
Conner Daube ◽  
Scott C. Herndon ◽  
W. Berk Knighton ◽  
...  
Keyword(s):  
San Antonio ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Urban Center ◽  
Entire Region ◽  
Volatile Organic ◽  
In Situ Observations ◽  
Study Sites

Abstract. Observations of total peroxy radicals (XO2 = RO2 + HO2) made by the Ethane CHemical AMPlifier (ECHAMP) and concomitant observations of additional trace gases made onboard the Aerodyne Mobile Laboratory (AML) during May 2017 were used to characterize ozone production at three sites in the San Antonio, Texas region. Median daytime [O3] was 48 ppbv at the site downwind of central San Antonio. Higher concentrations of NO and XO2 at the downwind site also led to median daytime ozone production rates (P(O3)) of 4.2 ppbv hr−1, a factor of two higher than at the two upwind sites. The 95th percentile of P(O3) at the upwind site was 15.1 ppbv hr−1, significantly lower than values observed in Houston. In situ observations, as well as satellite retrievals of HCHO and NO3, suggest that the region is NOx limited for times after approximately 09:00 local time, before which ozone production is VOC-limited. Biogenic volatile organic compounds (VOC) comprised 55 % of total OH reactivity at the downwind site, with alkanes and non-biogenic alkenes responsible for less than 10 % of total OH reactivity in the afternoon, when ozone production was highest. To control ozone formation rates at the three study sites effectively, policy efforts should be directed at reducing NOx emissions. Observations in the urban center of San Antonio are needed to determine whether this policy is true for the entire region.

scholarly journals The changing role of organic nitrates in the removal and transport of NO<sub>x</sub>

2019 ◽  
Author(s):  
Paul S. Romer Present ◽  
Azimeh Zare ◽  
Ronald C. Cohen
Keyword(s):  
Air Pollution ◽  
The United States ◽  
Ozone Production ◽  
Organic Nitrates ◽  
Volatile Organic ◽  
Direct Formation ◽  
In Situ Observations ◽  
Changing Role

Abstract. A better understanding of the chemistry of nitrogen oxides (NONOx) is crucial to effectively reducing air pollution and predicting future air quality. The response of NOx lifetime to perturbations in emissions or in the climate system is set in large part by whether NOx loss occurs primarily by the direct formation of HNO3 or through the formation of alkyl and multifunctional nitrates (RONO2). Using 15 years of detailed in situ observations, we show that in the summertime continental boundary layer the relative importance of these two pathways can be well approximated by the relative likelihood that OH will react with NO2 or instead with a volatile organic compound (VOC). Over the past decades, changes in anthropogenic emissions of both NONOx and VOCs have led to a significant increase in the overall importance of RONO2 chemistry to NONOx loss. We find that this shift is associated with a decreased effectiveness of NONOx emissions reductions on ozone production in polluted areas and increased transport of NONOx from source to receptor regions. This change in chemistry, combined with changes in the spatial pattern of NONOx emissions, is observed to be leading to a flatter distribution of NO2 across the United States, potentially transforming ozone air pollution from a local issue into a regional one.

scholarly journals Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations

2019 ◽  
Vol 116 (23) ◽  
pp. 11171-11180 ◽  
Author(s):  
Glenn M. Wolfe ◽  
Julie M. Nicely ◽  
Jason M. St. Clair ◽  
Thomas F. Hanisco ◽  
Jin Liao ◽  
...  
Keyword(s):  
Ozone Production ◽  
Spatial And Temporal Variability ◽  
Sources And Sinks ◽  
Building Process ◽  
Tightly Coupled ◽  
Remote Troposphere ◽  
In Situ Observations ◽  
Mean Concentration ◽  
Total Column

The hydroxyl radical (OH) fuels tropospheric ozone production and governs the lifetime of methane and many other gases. Existing methods to quantify global OH are limited to annual and global-to-hemispheric averages. Finer resolution is essential for isolating model deficiencies and building process-level understanding. In situ observations from the Atmospheric Tomography (ATom) mission demonstrate that remote tropospheric OH is tightly coupled to the production and loss of formaldehyde (HCHO), a major hydrocarbon oxidation product. Synthesis of this relationship with satellite-based HCHO retrievals and model-derived HCHO loss frequencies yields a map of total-column OH abundance throughout the remote troposphere (up to 70% of tropospheric mass) over the first two ATom missions (August 2016 and February 2017). This dataset offers unique insights on near-global oxidizing capacity. OH exhibits significant seasonality within individual hemispheres, but the domain mean concentration is nearly identical for both seasons (1.03 ± 0.25 × 106 cm−3), and the biseasonal average North/South Hemisphere ratio is 0.89 ± 0.06, consistent with a balance of OH sources and sinks across the remote troposphere. Regional phenomena are also highlighted, such as a 10-fold OH depression in the Tropical West Pacific and enhancements in the East Pacific and South Atlantic. This method is complementary to budget-based global OH constraints and can help elucidate the spatial and temporal variability of OH production and methane loss.

Biogeochemistry and Climate

2019 ◽  
pp. 29-43
Author(s):  
Han Dolman
Keyword(s):  
Ice Cores ◽  
Atmospheric Composition ◽  
System Modelling ◽  
Biogeochemical Processes ◽  
Sources And Sinks ◽  
Direct Observations ◽  
Geological Processes ◽  
In Situ Observations ◽  
Insight Into

This chapter focuses on tools for climate research: biogeochemical observations and models. It discusses physical climate observations, such as temperature and humidity, and in situ observations of atmospheric composition. Turning these into reliable climate records appears to be non-trivial. The chapter describes how isotopes are used to get insight into biogeochemical processes. A special category of observations is biogeochemical proxy observations, used to gain insight into geological processes when no direct observations are possible. The example of climate proxy observations, such as those obtained via ice cores, is described. Models are increasingly used to gain insight into sensitivity of climate to changes in the forcing. Earth system modelling has become increasingly complex over the last two decades, including often detailed biogeochemical processes in the ocean and on land. The parametrization of these remains an important research subject. Inverse modelling is being used to identify sources and sinks of greenhouse gases.

Age of Air in the Stratosphere from Observations

2020 ◽  
Author(s):  
Marianna Linz ◽  
Benjamin Birner ◽  
Alan Plumb ◽  
Edwin Gerber ◽  
Florian Haenel ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Sulfur Hexafluoride ◽  
Trace Gases ◽  
Trace Gas ◽  
Calculation Methods ◽  
Stratospheric Circulation ◽  
Tracer Age ◽  
Compact Relationship

&lt;p&gt;Age of air is an idealized tracer often used as a measure of the stratospheric circulation. We will show how to quantitatively relate age to the diabatic circulation and the adiabatic mixing. As it is an idealized tracer, age cannot be measured itself and must be inferred from other tracers. Typically, the two primary trace gases used are sulfur hexafluoride and carbon dioxide. Other tracers have a compact relationship with age, however, and can also be used to calculate age. We will discuss a range of tracer measurements from both satellites and in situ, including sulfur hexafluoride, carbon dioxide, nitrous oxide, methane, and the ratio of argon to nitrogen. We will compare the age derived from these different species, including different calculation methods and caveats, and compare with modeled ideal age and trace gas concentrations. We conclude by showing the strength of the diabatic circulation and the adiabatic mixing calculated from these trace gas calculations.&lt;/p&gt;

Cross-isentropic mixing: A DEEPWAVE case study

2020 ◽  
Author(s):  
Hans-Christoph Lachnitt ◽  
Peter Hoor ◽  
Daniel Kunkel ◽  
Stafan Hofmann ◽  
Martina Bramberger ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Trace Gases ◽  
Measurement Data ◽  
Wave Activity ◽  
Southern Alps ◽  
Trace Gas ◽  
Leeward Side ◽  
Mixing Processes ◽  
Stability Parameters

&lt;p&gt;The tropopause acts as a transport barrier between the upper troposphere and the lower stratosphere. Non-conservative (i.e. PV changing) processes are required to overcome this barrier. Orographically generated gravity waves (i.e. mountain waves) can potentially lead to cross-isentropic fluxes of trace gases via the generation of turbulence. Thus they may alter the isentropic gradient of these trace species across the tropopause.&lt;br&gt;The specific goal of this study is to identify cross-isentropic mixing processes at the tropopause based on the distribution of trace gases (i.e. tracer-tracer correlations). Based on airborne in-situ trace gas measurements of CO and N&lt;sub&gt;2&lt;/sub&gt;O during the DEEPWAVE (Deep Propagating Gravity Wave Experiment) campaign in July 2014 we identified mixing regions above the Southern Alps during periods of gravity wave activity. These in-situ data show that the composition of the air above the Southern Alps change from the upstream to the leeward side of the mountains indicating cross isentropic mixing of trace gases in the region of gravity wave activity.&lt;br&gt;We complement our analysis of the measurement data with high resolution operational analysis data from the ECMWF (European Centre for Medium-Range Weather Forecasts). Furthermore, using potential vorticity and stability parameters.&lt;br&gt;Using 3D wind fields, data form Graphical Turbulence Guidance (GTG) system and in-situ measurements of the vertical wind we identify occurrence of turbulence in the region of mixing events. Using wavelet analysis, we could identify the spatial and temporal scales of local trace gas fluxes. We also give estimates of cross-isentropic flux, i.e. we want to quantify the mixing in terms of exchange.&lt;/p&gt;

scholarly journals Seasonal cycles and variability of O<sub>3</sub> and H<sub>2</sub>O in the UT/LMS during SPURT

2006 ◽  
Vol 6 (1) ◽  
pp. 109-125 ◽  
Author(s):  
M. Krebsbach ◽  
C. Schiller ◽  
D. Brunner ◽  
G. Günther ◽  
M. I. Hegglin ◽  
...  
Keyword(s):  
Trace Gases ◽  
Distribution Functions ◽  
Trace Gas ◽  
Large Set ◽  
Transport Barrier ◽  
Tropical Tropopause ◽  
Time Period ◽  
Data Coverage ◽  
Insight Into

Abstract. Airborne high resolution in situ measurements of a large set of trace gases including ozone (O3) and total water (H2O) in the upper troposphere and the lowermost stratosphere (UT/LMS) have been performed above Europe within the SPURT project. SPURT provides an extensive data coverage of the UT/LMS in each season within the time period between November 2001 and July 2003. In the LMS a distinct spring maximum and autumn minimum is observed in O3, whereas its annual cycle in the UT is shifted by 2–3 months later towards the end of the year. The more variable H2O measurements reveal a maximum during summer and a minimum during autumn/winter with no phase shift between the two atmospheric compartments. For a comprehensive insight into trace gas composition and variability in the UT/LMS several statistical methods are applied using chemical, thermal and dynamical vertical coordinates. In particular, 2-dimensional probability distribution functions serve as a tool to transform localised aircraft data to a more comprehensive view of the probed atmospheric region. It appears that both trace gases, O3 and H2O, reveal the most compact arrangement and are best correlated in the view of potential vorticity (PV) and distance to the local tropopause, indicating an advanced mixing state on these surfaces. Thus, strong gradients of PV seem to act as a transport barrier both in the vertical and the horizontal direction. The alignment of trace gas isopleths reflects the existence of a year-round extra-tropical tropopause transition layer. The SPURT measurements reveal that this layer is mainly affected by stratospheric air during winter/spring and by tropospheric air during autumn/summer. Normalised mixing entropy values for O3 and H2O in the LMS appear to be maximal during spring and summer, respectively, indicating highest variability of these trace gases during the respective seasons.

OH reactivity in three major city clusters of China in ozone seasons: insights for regional ozone formation

2020 ◽  
Author(s):  
Shengrong Lou ◽  
Xiangsen Shen ◽  
Xin Li ◽  
Qian Wang ◽  
Shuoying Liu
Keyword(s):  
Control Strategies ◽  
Ambient Air ◽  
Ozone Production ◽  
Trace Gas ◽  
Ozone Formation ◽  
Oh Radical ◽  
Ozone Pollution ◽  
Major City ◽  
Photochemical Process

&lt;p&gt;&lt;span&gt;OH radical is the key driver of the photochemical process and closely related to ozone formation. OH reactivity is the quantification of OH radical sink in ambient air. In this study, in-situ OH reactivity measurements are carried out in Shenzhen, Chengdu and Changzhou, three typical cities in major city clusters of China, during their ozone pollution seasons. The measured OH reactivity is ranging from 5~35 s-1 under various meteorological conditions and trace gas concentrations. Aldehydes such as HCHO and acetaldehyde, mainly from the secondary formation of VOCs, are the principal contributors at day time. Primary VOCs such as toluene and biogenic VOCs such as isoprene play different roles in three measurement locations. The missing OH reactivity, which is defined as the OH reactivity that cannot be explained by trace gas measurements, are evaluated by in-situ measurement results as well as an observation-based model. Gas-phase secondary pollutants could be the main source of the missing OH reactivity. The sensitivity tests by the OBM model show ozone production in all areas is mainly VOC-limited but the key precursors of ozone are not identical, leading to different control strategies.&lt;/span&gt;&lt;/p&gt;

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