scholarly journals An instrument for in-situ measurement of total ozone reactivity

2019 ◽  
Author(s):  
Roberto Sommariva ◽  
Louisa J. Kramer ◽  
Leigh R. Crilley ◽  
Mohammed S. Alam ◽  
William J. Bloss
Keyword(s):  
Total Ozone ◽  
Diurnal Pattern ◽  
Aromatic Plants ◽  
Ambient Conditions ◽  
Mixing Ratios ◽  
Ozone Reactivity ◽  
Ambient Levels ◽  
Made In

Abstract. We present an instrument for the measurement of total ozone reactivity (RO3), i.e. the reciprocal of the chemical lifetime of ozone (O3) in the troposphere. The Total Ozone Reactivity System (TORS) was developed with the objective to study the role of biogenic organic compounds (BVOCs) as chemical sinks of tropospheric ozone. The instrument was extensively characterized and tested in the laboratory using individual compounds and small plants (lemonthyme, Thymus citriodorus) in a Teflon bag and proved able to measure reactivities corresponding to > 4.5 × 10−5 s−1, corresponding to 20 ppb of α-pinene or 150 ppb of isoprene in isolation – larger than typical ambient levels but consistent with levels commonly found in environmental chamber and enclosure experiments. The functionality of TORS was demonstrated in quasi-ambient conditions with a deployment in a horticultural glasshouse containing a range of aromatic plants. The measurements of total ozone reactivity made in the glasshouse showed a clear diurnal pattern, following the emissions of BVOCs, and is consistent with mixing ratios of tens ppb of monoterpenes and several ppb of sesquiterpenes.

scholarly journals An instrument for in situ measurement of total ozone reactivity

2020 ◽  
Vol 13 (3) ◽  
pp. 1655-1670
Author(s):  
Roberto Sommariva ◽  
Louisa J. Kramer ◽  
Leigh R. Crilley ◽  
Mohammed S. Alam ◽  
William J. Bloss
Keyword(s):  
Total Ozone ◽  
Ambient Conditions ◽  
Total Uncertainty ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
Averaging Time ◽  
Ozone Reactivity ◽  
Made In

Abstract. We present an instrument for the measurement of total ozone reactivity – the reciprocal of the chemical lifetime of ozone (O3) – in the troposphere. The Total Ozone Reactivity System (TORS) was developed with the objective to study the role of biogenic volatile organic compounds (BVOCs) as chemical sinks of tropospheric ozone. The instrument was extensively characterized and tested in the laboratory using individual BVOCs and small plants (lemon thyme, Thymus citriodorus) in a Teflon bag and proved able to measure reactivities corresponding to >4.5×10-5 s−1 (at 5 min averaging time), with an estimated total uncertainty of ∼32%. Such reactivities correspond to >20 ppb of α-pinene or >150 ppb of isoprene in isolation – larger than typical ambient levels but observable in environmental chamber and enclosure experiments as well as in BVOC-rich environments. The functionality of TORS was demonstrated in quasi-ambient conditions with a deployment in a horticultural glasshouse containing a range of aromatic plants. The measurements of total ozone reactivity made in the glasshouse showed a clear diurnal pattern, following the emissions of BVOCs, and are consistent with mixing ratios of tens of parts per billion of monoterpenes and several parts per billion of sesquiterpenes.

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

2021 ◽  
Vol 21 (10) ◽  
pp. 8195-8211
Author(s):  
Ivan Tadic ◽  
Clara M. Nussbaumer ◽  
Birger Bohn ◽  
Hartwig Harder ◽  
Daniel Marno ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Atlantic Ocean ◽  
General Circulation ◽  
Simulated Data ◽  
Ozone Production ◽  
Mixing Ratios ◽  
Western Africa ◽  
Tropical Troposphere

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.

Investigation of transport in the northern lowermost stratosphere between spring and fall using airborne in situ tracer measurements

2020 ◽  
Author(s):  
Andrea Rau ◽  
Valentin Lauther ◽  
Johannes Wintel ◽  
Emil Gehardt ◽  
Peter Hoor ◽  
...  
Keyword(s):  
Time Scales ◽  
Asian Monsoon ◽  
Lagrangian Model ◽  
Mixing Ratios ◽  
Tropical Tropopause ◽  
Research Aircraft ◽  
Transport And Mixing ◽  
The University

<p>Over the course of the summer, when the subtropical jet is weakest, quasi-isentropic transport of young air from the troposphere and the tropical tropopause layer into the northern hemisphere (NH) lowermost stratosphere (LMS) is increased resulting in a drastic change of LMS chemical composition between spring and fall. The focus of this work is on the role of different transport paths into the NH LMS, including outflow from the Asian Monsoon, and their associated time scales of transport and mixing.<br><br>We present and analyse in situ measurements of CO<sub>2</sub> and various long-lived tracers obtained during three recent aircraft campaigns encompassing over 40 research flights in the NH UTLS during winter/spring, summer, and fall. The POLSTRACC/GW-LCYCLE/SALSA campaign probed the northern high latitude LMS in winter/spring 2016, deploying the German research aircraft HALO from Kiruna (Sweden) and from Germany. The second campaign deployed the M55 Geophysica research aircraft in July/August 2017 from Kathmandu, Nepal, in the frame of the EU-funded project StratoClim (Stratospheric and upper tropospheric processes for better Climate predications) in order to probe in situ for the first time the inside of the Asian Monsoon anticyclone. Roughly two months later the WISE (Wave-driven ISentropic Exchange) campaign deployed again HALO from Shannon (Ireland) in September and October 2017 to investigate isentropic transport and mixing in the NH LMS.<br><br>The University of Wuppertal measured CO<sub>2</sub> and a suite of long-lived tracers on each aircraft. On the Geophysica, the measurements were made with the HAGAR (High Altitude Gas AnalyzeR) instrument. On HALO, a recently developed extended 5-channel version, HAGAR-V, was flown, which in addition measured a suite of short-lived tracers by GC coupled with a mass spectrometer. The University of Mainz measured N2O and CO on HALO using laser absorption techniques. For our analysis we use mixing ratios of CO<sub>2</sub>, SF<sub>6</sub>, CFC-11, CFC-12, and N<sub>2</sub>O.<br><br>Owing to their different lifetimes, tropospheric growth (for SF<sub>6</sub>) and a seasonal cycle (for CO<sub>2</sub>), the LMS distributions of these long-lived trace gases and their development between spring and fall contain key information about the origin and mean stratospheric age of LMS air as well as time scales of rapid isentropic transport and mixing. The analysis of tracer measurements is complemented by simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) providing information on age of air spectra and fractions of origin from specific surface regions, allowing in particular to assess the role of the Asian Monsoon in determining the composition of the NH LMS in fall.</p>

scholarly journals Identifying areas prone to coastal hypoxia – the role of topography

2019 ◽  
Author(s):  
Elina A. Virtanen ◽  
Alf Norkko ◽  
Antonia Nyström Sandman ◽  
Markku Viitasalo
Keyword(s):  
Oxygen Deficiency ◽  
Coastal Areas ◽  
Management Actions ◽  
In Situ Data ◽  
Efficient Management ◽  
Stockholm Archipelago ◽  
Oxygen Dynamics ◽  
Made In

Abstract. Hypoxia is an increasing problem in marine ecosystems around the world, and recent projections indicate that anoxic dead zones will be spreading in the forthcoming decades. While major advances have been made in our understanding of the drivers of hypoxia, it fundamentally hinges on patterns of water circulation that can be difficult to resolve in coastal regions. The complexity of many coastal areas and lack of detailed in situ data has hindered the development of models describing oxygen dynamics at a sufficient resolution for efficient management actions to take place. We hypothesized that the enclosed nature of seafloors facilitates hypoxia formation. We developed simple proxies of seafloor heterogeneity and modelled oxygen deficiency in complex coastal areas in the northern Baltic Sea. We discovered that topographically sheltered seafloors and sinkholes with stagnant water are prone to the development of hypoxia. Approximately half of the monitoring sites in Stockholm Archipelago and one third of sites in southern Finland experienced severe hypoxia (O2 

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

2021 ◽  
Author(s):  
Ivan Tadic ◽  
Clara Nussbaumer ◽  
Birger Bohn ◽  
Hartwig Harder ◽  
Daniel Marno ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Simulated Data ◽  
West African ◽  
Ozone Production ◽  
African Continent ◽  
The West ◽  
Mixing Ratios ◽  
Tropical Troposphere

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.

scholarly journals Vertical profile of peroxyacetyl nitrate (PAN) from MIPAS-STR measurements over Brazil in February 2005 and the role of PAN in the UT tropical NO<sub>y</sub> partitioning

2008 ◽  
Vol 8 (2) ◽  
pp. 6983-7016
Author(s):  
C. Keim ◽  
G. Y. Liu ◽  
C. E. Blom ◽  
H. Fischer ◽  
T. Gulde ◽  
...  
Keyword(s):  
Vertical Profile ◽  
Trace Gases ◽  
Remote Sensor ◽  
Research Aircraft ◽  
Careful Handling ◽  
Tropical Troposphere ◽  
Selection Of ◽  
Made In

Abstract. We report on the retrieval of PAN (CH3C(O)OONO2) in the upper tropical troposphere from limb measurements by the remote-sensor MIPAS-STR on board the Russian high altitude research aircraft M55-Geophysica. The measurements were performed close to Araçatuba, Brazil, on 17 February 2005. The retrieval was made in the spectral range 775–820 cm−1 where PAN exhibits its strongest feature but also more than 10 species interfere. Especially trace gases such as CH3CCl3, CFC-113, CFC-11, and CFC-22, emitting also in spectrally broad not-resolved branches, make the processing of PAN prone to errors. Therefore, the selection of appropriate spectral windows, the separate retrieval of several interfering species and the careful handling of the water vapour profile are part of the study presented. The retrieved profile of PAN has a maximum of about 0.14 ppbv at 10 km altitude, slightly larger than the lowest reported values (<0.1 ppbv) and much lower than the highest (0.65 ppbv). Besides the NOy constituents measured by MIPAS-STR (HNO3, ClONO2, PAN), the situ instruments aboard the Geophysica provide simultaneous measurements of NO, NO2, and the sum NOy. Comparing the sum of in-situ and remotely derived NO+NO2+HNO3+ClONO2+PAN with total NOy a deficit of 30–40% (0.2–0.3 ppbv) in the troposphere remains unexplained whereas the values fit well in the stratosphere.

scholarly journals Role of location, season, occupant activity, and chemistry in indoor ozone and nitrogen oxide mixing ratios

2019 ◽  
Vol 21 (8) ◽  
pp. 1374-1383 ◽  
Author(s):  
Shan Zhou ◽  
Cora J. Young ◽  
Trevor C. VandenBoer ◽  
Tara F. Kahan
Keyword(s):  
Nitrogen Oxide ◽  
Field Studies ◽  
Mixing Ratios

Indoor field studies and in situ chamber experiments illustrate the interdependence of oxidants and oxidant precursors in residences.

scholarly journals Single-walled carbon nanotubes/lithium borohydride composites for hydrogen storage: role of in situ formed LiB(OH)4, Li2CO3 and LiBO2 by oxidation and nitrogen annealing

RSC Advances ◽  
2019 ◽  
Vol 9 (54) ◽  
pp. 31483-31496 ◽  
Author(s):  
Lathapriya Vellingiri ◽  
Karthigeyan Annamalai ◽  
Ramamurthi Kandasamy ◽  
Iyakutti Kombiah
Keyword(s):  
Catalytic Effect ◽  
Single Walled Carbon Nanotubes ◽  
Ambient Conditions ◽  
Lithium Borohydride ◽  
Hydrogenation Kinetics ◽  
Nitrogen Annealing ◽  
Walled Carbon Nanotubes ◽  
Kinetics Of

In situ formed Li+[B(OH)4]−, Li2+[CO3]− & Li+[BO2]− on the surface of SWCNT@LiBH4 not only stabilizes the composites in ambient conditions but also enhanced the de- and re-hydrogenation kinetics of the composites through catalytic effect.

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