Christopher Cantrell - Academia.edu (original) (raw)

Papers by Christopher Cantrell

Atmospheric Chemistry and Physics, 2018

The evolution of organic aerosols (OAs) and their precursors in the boundary layer (BL) of the Co... more The evolution of organic aerosols (OAs) and their precursors in the boundary layer (BL) of the Colorado Front Range during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ, July-August 2014) was analyzed by in situ measurements and chemical transport modeling. Measurements indicated significant production of secondary OA (SOA), with enhancement ratio of OA with respect to carbon monoxide (CO) reaching 0.085 ± 0.003 µg m −3 ppbv −1. At background mixing ratios of CO, up to ∼ 1.8 µg m −3 background OA was observed, suggesting significant non-combustion contribution to OA in the Front Range. The mean concentration of OA in plumes with a high influence of oil and natural gas (O&G) emissions was ∼ 40 % higher than in urban-influenced plumes. Positive matrix factorization (PMF) confirmed a dominant contribution of secondary, oxygenated OA (OOA) in the boundary layer instead of fresh, hydrocarbon-like OA (HOA). Combinations of primary OA (POA) volatility assumptions, aging of semivolatile species, and different emission estimates from the O&G sector were used in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) simulation scenarios. The assumption of semi-volatile POA resulted in greater than a factor of 10 lower POA concentrations compared to PMF-resolved HOA. Including top-down modified O&G emissions resulted in substantially better agreements in modeled ethane, toluene, hydroxyl radical, and ozone compared to measurements in the high-O&G-influenced plumes. By including emissions from the O&G sector using the topdown approach, it was estimated that the O&G sector contributed to < 5 % of total OA, but up to 38 % of anthropogenic SOA (aSOA) in the region. The best agreement between the measured and simulated median OA was achieved by limiting the extent of biogenic hydrocarbon aging and consequently biogenic SOA (bSOA) production. Despite a Published by Copernicus Publications on behalf of the European Geosciences Union. 8294 R. Bahreini et al.: Perspective from measurements and WRF-Chem modeling lower production of bSOA in this scenario, contribution of bSOA to total SOA remained high at 40-54 %. Future studies aiming at a better emissions characterization of POA and intermediate-volatility organic compounds (IVOCs) from the O&G sector are valuable.

Atmospheric Chemistry and Physics Discussions, 2016

Ozone depletion events (ODEs) in the Arctic are primarily controlled by a bromine radical-catalyz... more Ozone depletion events (ODEs) in the Arctic are primarily controlled by a bromine radical-catalyzed destruction mechanism that depends on the efficient production and recycling of Br atoms. Numerous laboratory and modeling studies have suggested the importance of heterogeneous recycling of Br through HOBr reaction with bromide on saline surfaces. However, the gas-phase regeneration of bromine atoms through BrO-BrO radical reactions has been assumed to be an efficient, if not dominant, pathway for Br reformation and thus ozone destruction. Indeed, it has been estimated that the rate of ozone depletion is approximately equal to twice the rate of the BrO self-reaction. Here, we use a zero-dimensional, photochemical model, largely constrained to observations of stable atmospheric species from the 2009 OASIS campaign in Barrow, Alaska, to investigate gas-phase bromine radical propagation and heterogeneous recycling of bromine for a seven-day period during late March. We find that the gas...

Advances in Chemistry, 1993

Page 1. 11 Measurement Methods for Peroxy Radicals in the Atmosphere Chris A. Cantrell, Richard E... more Page 1. 11 Measurement Methods for Peroxy Radicals in the Atmosphere Chris A. Cantrell, Richard E. Shetter, Anthony H. McDaniel, and Jack G. Calvert Atmospheric Kinetics and Photochemistry Group, Atmospheric Chemistry ...

The Journal of Physical Chemistry, 1990

Page 1. 3902 J. Phys. Chem. 1990, 94, 3902-3908 CHART I1 5 6 7 8 Experimental Section Materials. ... more Page 1. 3902 J. Phys. Chem. 1990, 94, 3902-3908 CHART I1 5 6 7 8 Experimental Section Materials. The solvents used were spectroscopic grade Merck products. Synthesis of compounds 1-4, ad, has already been reported.' Synthesis. ...

SPIE Proceedings, 1991

Chemical amplifier for peroxy radical measurements based on luminol chemiluminescence. [Proceedin... more Chemical amplifier for peroxy radical measurements based on luminol chemiluminescence. [Proceedings of SPIE 1433, 263 (1991)]. Chris A. Cantrell, Richard E. Shetter, John A. Lind, Curt A. Gilliland, Jack G. Calvert. Abstract. ...

Journal of the Atmospheric Sciences, 1995

Journal of Geophysical Research: Atmospheres, 1990

Laboratory experiments were performed to measure the ratio of rate constants for reactions (R3): ... more Laboratory experiments were performed to measure the ratio of rate constants for reactions (R3): NO3 + NO → 2 NO2 and (R4): NO2 + NO3 → NO + NO2 + O2. This was accomplished through direct measurement of the nitric oxide and nitrogen dioxide concentrations in an N2O5/NO2/N2 mixture over the temperature range from 273 to 313 K. The measured ratio is represented by the expression, k3/k4 = 387 exp(−1375/T). The result, when combined with measurements of k3 in order to determine k4, is in reasonable agreement with other recent results from this laboratory; however, it is approximately a factor of 2 smaller than earlier reports. The experimental details are reported along with possible atmospheric implications of this result.

Journal of Geophysical Research: Atmospheres, 1997

Abstract. The present study examines in detail the photochemistry of the important hydrocarbon in... more Abstract. The present study examines in detail the photochemistry of the important hydrocarbon intermediate HCHO during the 1993 Fritz Peak/Idaho Hill OH Photochemistry Experiment. Measurement-model relationships for HCHO were studied employing a box model with ...

Journal of Atmospheric Chemistry, 1991

The infrared absorption cross-sections for eight commonly used halogenated methanes and ethanes h... more The infrared absorption cross-sections for eight commonly used halogenated methanes and ethanes have been measured as a function of temperature from 203 to 293 K. High resolution spectra (0.03 cm-l) have been used to derive integrated band strengths and peak cross-sections associated with the spectral features in the infrared region from 600 to 1500 cm-2. The values obtained in this study are compared to those from previous reports, and recommendations are made for uses in atmospheric sensing and radiative energy transfer models. The observed temperature dependence in the spectral features is also discussed.

Chemical Physics Letters, 1988

Laboratory measurements of absolute infrared absorption cross sections for three strong bands of ... more Laboratory measurements of absolute infrared absorption cross sections for three strong bands of NzOs have been made as a function of temperature from 233 to 350 K. The results of this study confirm most of the recent laboratory studies, indicating reasonable confidence in cross sections for this molecule which are of potential use in its identification and measurement in the atmosphere and in laboratory systems. Beer-Lambert linearity is confirmed and the effect of instrumental resolution on integrated intensities as well as peak cross sections is reported.

Atmospheric Chemistry and Physics, 2017

Chemical models must correctly calculate the ozone formation rate, P(O 3), to accurately predict ... more Chemical models must correctly calculate the ozone formation rate, P(O 3), to accurately predict ozone levels and to test mitigation strategies. However, air quality models can have large uncertainties in P(O 3) calculations, which can create uncertainties in ozone forecasts, especially during the summertime when P(O 3) is high. One way to test mechanisms is to compare modeled P(O 3) to direct measurements. During summer 2014, the Measurement of Ozone Production Sensor (MOPS) directly measured net P(O 3) in Golden, CO, approximately 25 km west of Denver along the Colorado Front Range. Net P(O 3) 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(O 3) 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(O 3) 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(O 3) behavior. Modeled and measured P(O 3) and peroxy radical (HO 2 and RO 2) discrepancies observed here are similar to those presented in prior studies. While a missing atmospheric organic peroxy radical source from volatile organic compounds coemitted with NO could be one plausible solution to the P(O 3) 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(O 3), then these results would imply that P(O 3) in Golden, CO, would be NO x-sensitive for more of the day than what is calculated by models, extending the NO x-sensitive P(O 3) regime from the afternoon further into the morning. These results could Published by Copernicus Publications on behalf of the European Geosciences Union. 11274 B. C. Baier et al.: Higher measured than modeled ozone production 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(O 3), especially under high-NO x regimes.

AIP Conference Proceedings, 2000

Nucleation and growth of SOA were observed from the reaction products of α-pinene and ozone, util... more Nucleation and growth of SOA were observed from the reaction products of α-pinene and ozone, utilizing relatively low concentrations of α-pinene (16 ppb) and ozone (95 ppb). Good agreement between observed and modeled results was obtained when the yield was ...

Airborne gas phase measurements of sulfur dioxide, dimethylsulfide, dimethylsulfoxide, methane su... more Airborne gas phase measurements of sulfur dioxide, dimethylsulfide, dimethylsulfoxide, methane sulfonic acid, sulfuric acid, hydroxyl, perhydroxyl, hydrogen peroxide, methylhydroperoxide, ozone, and carbon monoxide together with aerosol microphysical properties and bulk and size-dependent aerosol composition are examined for consistency with photochemical theory. The observations come from 14 research flights using the NCAR C-130 flown mostly southeast of Kiritimati in relatively cloud-free

The kinetics of the reaction NOâ + CHâO ..cap alpha.. HONOâ + HCO (14) have been studied by using... more The kinetics of the reaction NOâ + CHâO ..cap alpha.. HONOâ + HCO (14) have been studied by using in situ, long-path (170 m), infrared and visible spectroscopy to follow the reactants and products in dilute mixtures of Oâ, NOâ, and CHâO in Nâ/Oâ at 700 torr (25 +/- 2Â°C). The concentrations of Oâ, NOâ, CHâO, NâOâ, CO, HONOâ, and HCOâH were determined as a function of time through their characteristic infrared absorption bands by using a Fourier transform infrared spectrometer system. The concentrations of NOâ and NOâ were followed by using the characteristic visible absorption bands monitored by a differential optical absorption spectrometer. The kinetic data were analyzed by using both rates of product formation (CO) and reactant removal (NâOâ, NOâ, CHâO) and computer simulations. 44 references, 2 figures, 3 tables.

Journal of Geophysical Research: Atmospheres, 2001

Observations of particle nucleation and growth during ozonolysis of c•-pinene were carried out in... more Observations of particle nucleation and growth during ozonolysis of c•-pinene were carried out in Calspan's 600 m 3 environmental chamber utilizing relatively low concentrations of c•-pinene (15 ppb) and ozone (100 ppb). Model simulations with a comprehensive sectional aerosol model which incorporated the relevant gas-phase chemistry snow that the uuserced •' ^"'

Journal of Geophysical Research, 2001

A series of controlled experiments were carried out in the Calspan Corporation's 600 m 3 environm... more A series of controlled experiments were carried out in the Calspan Corporation's 600 m 3 environmental chamber to study some secondary organic aerosol formation processes. Three precursor-ozone systems were studied: cyclopentene-ozone, cyclohexene-ozone, and ct-pineneozone. Additionally, SO2 was added to the initial gas mixture in several instances and was likely present at trace levels in the ostensibly organic-only experime•.ts. It was found that all three systems readily formed new submicron aerosols at very low reactant levels. The chemical composition of formed aerosols was consistent with some previous studies, but the yields of organic products were found to be lower in the Calspan experiments. A three-step procedure is proposed to explain the observed particle nucleation behavior: HO. production-• H2SO 4 formation-• H2SO4-H20 (perhaps together with NH3) homogeneous nucleation. It is also proposed that some soluble organic products would partition into the newly formed H2SO4-H20 nuclei, enhance water condensation, and quickly grow these nuclei into a larger size range. While the observations in the two cycloolefin-ozone systems could be well explained by these proposed mechanisms, the exact nature of the nucleation process in the o•-pinene-ozone system remains rather opaque and could be the result of nucleation involving certain organics. The results from three simple modeling studies further support these proposals. Their applicability to the marine boundary layer (MBL) is also discussed in some detail. Particularly, such a particle nucleation and growth process could play an important role in secondary aerosol formation and, quite likely, CCN formation as well in certain MBL regions. 1991; Chow et al., 1994; Novakov et al., 1997]. In the marine boundary layer (MBL), according to the results from the First Aerosol Characterization Experiment (ACE 1), at least 10% of the marine aerosol mass is organic matter. In fact, organics and sulfate have been found to be often present in a single aerosol particle [Murphy et al., 1998]. There have also been measurements showing that in both the polluted and background marine atmosphere, organic aerosols can play as important a role in cloud condensation nuclei (CCN) formation as sulfate aerosols [Novakov and Penner, 1993; Matsumoto et

Journal of Geophysical Research, 2003

The Tropospheric Ozone Production about the Spring Equinox (TOPSE) experiment was conducted durin... more The Tropospheric Ozone Production about the Spring Equinox (TOPSE) experiment was conducted during February-March, 2000 to study the evolution of tropospheric chemistry at mid to high latitudes over North America. The experiment used airborne in situ and remote sensing measurements of trace gases, radiation, and aerosols, combined with model simulations, to describe the major processes that control evolution of ozone and oxidants during the winter-spring transition. This paper introduces the major scientific questions of the TOPSE experiment, describes the conduct of the mission, and introduces the scientific results discussed in a series of companion papers in this special section. Among the significant findings of the experiment was that tropospheric ozone increases from winter to spring were dominated by in situ photochemical production in the troposphere, rather than by transport from the stratosphere. Also unique observations of widespread surface ozone depletion events, and of seasonal evolution of trace gases and aerosols as a function of latitude and altitude, were obtained over the course of the mission.