An estimation of ozone flux in a stratosphere-troposphere exchange event

Abstract. Understanding the fate of ozone within and above forested environments is vital to assessing the anthropogenic impact on ecosystems and air quality at the urban-rural interface. Observed forest-atmosphere exchange of ozone is often much faster than explicable by stomatal uptake alone, suggesting the presence of additional ozone sinks within the canopy. Using the Chemistry of Atmosphere-Forest Exchange (CAFE) model in conjunction with summer noontime observations from the 2007 Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX-2007), we explore the viability and implications of the hypothesis that ozonolysis of very reactive but yet unidentified biogenic volatile organic compounds (BVOC) can influence the forest-atmosphere exchange of ozone. Non-stomatal processes typically generate 67 % of the observed ozone flux, but reactions of ozone with measured BVOC, including monoterpenes and sesquiterpenes, can account for only 2 % of this flux during the selected timeframe. By incorporating additional emissions and chemistry of a proxy for very reactive VOC (VRVOC) that undergo rapid ozonolysis, we demonstrate that an in-canopy chemical ozone sink of ~2 × 108 molec cm−3 s−1 can close the ozone flux budget. Even in such a case, the 65 min chemical lifetime of ozone is much longer than the canopy residence time of ~2 min, highlighting that chemistry can influence reactive trace gas exchange even when it is "slow" relative to vertical mixing. This level of VRVOC ozonolysis could enhance OH and RO2 production by as much as 1 pptv s−1 and substantially alter their respective vertical profiles depending on the actual product yields. Reaction products would also contribute significantly to the oxidized VOC budget and, by extension, secondary organic aerosol mass. Given the potentially significant ramifications of a chemical ozone flux for both in-canopy chemistry and estimates of ozone deposition, future efforts should focus on quantifying both ozone reactivity and non-stomatal (e.g. cuticular) deposition within the forest.

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Nitrogen availability does not affect ozone flux-effect relationships for biomass in birch (Betula pendula) saplings

The Science of The Total Environment ◽

10.1016/j.scitotenv.2019.01.092 ◽

2019 ◽

Vol 660 ◽

pp. 1038-1046 ◽

Cited By ~ 10

Author(s):

Lulu Dai ◽

Felicity Hayes ◽

Katrina Sharps ◽

Harry Harmens ◽

Gina Mills

Keyword(s):

Betula Pendula ◽

Nitrogen Availability ◽

Ozone Flux

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Epinephrine syringe exchange events in a paediatric cardiovascular ICU: analysing the storm

Cardiology in the Young ◽

10.1017/s1047951117002232 ◽

2017 ◽

Vol 28 (3) ◽

pp. 409-415 ◽

Cited By ~ 5

Author(s):

Barbara-Jo Achuff ◽

Jameson C. Achuff ◽

Hwan H. Park ◽

Brady Moffett ◽

Sebastian Acosta ◽

...

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Systolic Blood Pressure ◽

Vital Signs ◽

Syringe Exchange ◽

Control Data ◽

Flow Change ◽

Exchange Event ◽

The Hours ◽

Pressure Perturbations

AbstractIntroductionHaemodynamically unstable patients can experience potentially hazardous changes in vital signs related to the exchange of depleted syringes of epinephrine to full syringes. The purpose was to determine the measured effects of epinephrine syringe exchanges on the magnitude, duration, and frequency of haemodynamic disturbances in the hour after an exchange event (study) relative to the hours before (control).Materials and methodsBeat-to-beat vital signs recorded every 2 seconds from bedside monitors for patients admitted to the paediatric cardiovascular ICU of Texas Children’s Hospital were collected between 1 January, 2013 and 30 June, 2015. Epinephrine syringe exchanges without dose/flow change were obtained from electronic records. Time, magnitude, and duration of changes in systolic blood pressure and heart rate were characterised using Matlab. Significant haemodynamic events were identified and compared with control data.ResultsIn all, 1042 syringe exchange events were found and 850 (81.6%) had uncorrupted data for analysis. A total of 744 (87.5%) exchanges had at least 1 associated haemodynamic perturbation including 2958 systolic blood pressure and 1747 heart-rate changes. Heart-rate perturbations occurred 37% before exchange and 63% after exchange, and 37% of systolic blood pressure perturbations happened before syringe exchange, whereas 63% occurred after syringe exchange with significant differences found in systolic blood pressure frequency (p<0.001), duration (p<0.001), and amplitude (p<0.001) compared with control data.ConclusionsThis novel data collection and signal processing analysis showed a significant increase in frequency, duration, and magnitude of systolic blood pressure perturbations surrounding epinephrine syringe exchange events.

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Suzaku detection of enigmatic geocoronal solar wind charge exchange event associated with coronal mass ejection

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psy142 ◽

2019 ◽

Vol 71 (1) ◽

Author(s):

Daiki Ishi ◽

Kumi Ishikawa ◽

Masaki Numazawa ◽

Yoshizumi Miyoshi ◽

Naoki Terada ◽

...

Keyword(s):

Solar Wind ◽

Coronal Mass Ejection ◽

Charge Exchange ◽

Exchange Event ◽

Solar Wind Charge Exchange ◽

Mass Ejection

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A Participatory Social A/r/tography: Bodies and Houses Metamorphosing from Schools in Tegucigalpa to a Liverpool Tate Exchange Event

International Journal of Art & Design Education ◽

10.1111/jade.12239 ◽

2019 ◽

Vol 38 (3) ◽

pp. 627-638

Author(s):

Ricardo Marin‐Viadel ◽

Alicia Arias‐Camison ◽

Ana Varea

Keyword(s):

Exchange Event

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Prediction of hot spots of ozone flux in a Rhesus monkey lung during steady inspiratory flow

2012 38th Annual Northeast Bioengineering Conference (NEBEC) ◽

10.1109/nebc.2012.6206958 ◽

2012 ◽

Author(s):

Banafsheh Keshavarzi ◽

James S. Ultman ◽

Ali Borhan

Keyword(s):

Rhesus Monkey ◽

Hot Spots ◽

Inspiratory Flow ◽

Ozone Flux

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Evaluation of the flux gradient technique for measurement of ozone surface fluxes over snowpack at Summit, Greenland

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-1021-2011 ◽

2011 ◽

Vol 4 (1) ◽

pp. 1021-1059

Author(s):

F. Bocquet ◽

D. Helmig ◽

B. A. Van Dam ◽

C. W. Fairall

Keyword(s):

Gradient Method ◽

Deposition Velocity ◽

Surface Fluxes ◽

Sensitivity Threshold ◽

Lower Sensitivity ◽

Ozone Deposition ◽

Ozone Flux ◽

Gradient Technique ◽

Measurement Height ◽

Polar Snow

Abstract. A multi-step procedure for investigating ozone surface fluxes over polar snow by the tower gradient method was developed and evaluated. These measurements were then used to obtain four months of turbulent ozone flux data at the Summit research camp located in the center of the Greenland ice shield. Turbulent fluxes were determined by the aerodynamic gradient method incorporating tower measurements of (a) ozone gradients measured by commercial ultraviolet absorption analyzers, (b) ambient temperature gradients using aspirated thermocouple sensors, and (c) wind speed gradients determined by cup anemometers. All gradient instruments were regularly inter-compared by bringing sensors or inlets to the same measurement height. The developed protocol resulted in an uncertainty on the order of 0.1 ppbv for 30-min averaged ozone gradients that were used for the ozone flux calculations. This protocol facilitated a lower sensitivity threshold for the ozone flux determination of −8 × 10−3 μg m−2 s−1, respectively ~0.01 cm s−1 for the ozone deposition velocity for typical environmental conditions encountered at Summit. Uncertainty in the 30-min ozone exchange measurements (evaluated by the Monte Carlo statistical approach) was on the order of 10−2 cm s−1. This uncertainty typically accounted to ~20–100% of the ozone exchange velocities that were determined. These measurements are among the most sensitive ozone deposition determinations reported to date. This flux experiment, deployed at Summit for a period of four months, allowed for measurements of the relatively low ozone uptake rates encountered for polar snow, and thereby the study of their environmental and seasonal dependencies.

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