OH ‐ Radicals in the lower troposphere

Perner, D.; Ehhalt, D. H.; Pätz, H.‐W.; Platt, U.; Roth, E.; Völz, Andreas

doi:10.1029/gl003i008p00466

Cited by 177 publications

(55 citation statements)

References 13 publications

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“…Differential optical absorption spectroscopy (DOAS) is an analysis technique first used by Perner et al (1976), and it is usually applied to analyse UV-VIS spectra with spectral resolution below 1 nm. The multi-axis UV-spectrometer used in this work will be called in the following MAX-DOAS.…”

Section: Measurementsmentioning

confidence: 99%

Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006–2009

Bobrowski

Giuffrida

2012

Solid Earth

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Abstract. Over a 3-yr period, from 2006 to 2009, frequent scattered sunlight DOAS measurements were conducted at Mt. Etna at a distance of around 6 km downwind from the summit craters. During the same period and in addition to these measurements, volcanic observations were made by regularly visiting various parts of Mt. Etna. Here, results from these measurements and observations are presented and their relation is discussed. The focus of the investigation is the bromine monoxide/sulphur dioxide (BrO / SO2) ratio, and its variability in relation to volcanic processes. That the halogen/sulphur ratio can serve as a precursor or indicator for the onset of eruptive activity was already proposed by earlier works (e.g. Noguchi and Kamiya 1963; Menyailov, 1975; Pennisi and Cloarec, 1998; Aiuppa et al., 2002). However, there is still a limited understanding today because of the complexity with which halogens are released, depending on magma composition and degassing conditions. Our understanding of these processes is far from complete, for example of the rate and mechanism of bubble nucleation, growth and ascent in silicate melts (Carroll and Holloway, 1994), the halogen vapour-melt partitioning and the volatile diffusivity in the melt (Aiuppa et al., 2009). With this study we aim to add one more piece to the puzzle of what halogen/sulphur ratios might tell about volcanic activities. Our data set shows an increase of the BrO / SO2 ratio several weeks prior to an eruption, followed by a decline before and during the initial phase of eruptive activities. Towards the end of activity or shortly thereafter, the ratio increases to baseline values again and remains more or less constant during quiet phases. To explain the observed evolution of the BrO / SO2 ratio, a first empirical model is proposed. This model suggests that bromine, unlike chlorine and fluorine, is less soluble in the magmatic melt than sulphur. By using the DOAS method to determine SO2, we actually observe most of the emitted sulphur of Mt.~Etna. Regarding bromine, however, we are aware that by determining only the bromine monoxide (BrO) radical we might just observe a small or even a variable fraction of the total emitted bromine, which is most probable originally in the form of HBr. Therefore, we present first studies to justify the assumption that, despite the disadvantage just mentioned, the BrO / SO2 ratio can nevertheless serve as a new parameter to indicate the state of a volcano, when measurements are conducted under certain, but rather convenient, conditions.

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Section: Measurementsmentioning

confidence: 99%

Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006–2009

Bobrowski

Giuffrida

2012

Solid Earth

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“…Tropospheric OH was detected for the first time by Perner et al (1976) using differential optical absorption spectroscopy (DOAS). Schlosser et al (2009) report that the most widely applied OH concentration measurement technique is laser-induced fluorescence (LIF) combined with a gas expansion, also known as fluorescence assay with gas expansion (FAGE).…”

Section: P Barmet Et Al: Oh Clock Determination By Proton Transfer mentioning

confidence: 99%

OH clock determination by proton transfer reaction mass spectrometry at an environmental chamber

et al. 2012

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Abstract. The hydroxyl free radical (OH) is the major oxidizing species in the lower atmosphere. Measuring the OH concentration is generally difficult and involves elaborate, expensive, custom-made experimental setups. Thus other more economical techniques, capable of determining OH concentrations at environmental chambers, would be valuable. This work is based on an indirect method of OH concentration measurement, by monitoring an appropriate OH tracer by proton transfer reaction mass spectrometry (PTR-MS). 3-pentanol, 3-pentanone and pinonaldehyde (PA) were used as OH tracers in α-pinene (AP) secondary organic aerosol (SOA) aging studies. In addition we tested butanold9 as a potential "universal" OH tracer and determined its reaction rate constant with OH: k butanol-d9 = 3.4(±0.88) × 10 −12 cm 3 molecule −1 s −1 . In order to make the chamber studies more comparable among each other as well as to atmospheric measurements we suggest the use of a chemical (time) dimension: the OH clock, which corresponds to the integrated OH concentration over time.

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“…Since then many attempts were made to measure OH concentrations in the troposphere by various techniques (see review by Heard and Pilling, 2003). For the first time tropospheric OH was detected by Perner et al (1976) in Jülich using Differential Optical Absorption Spectroscopy. DOAS based OH instruments were also developed in Frankfurt (Armerding et al, 1994) and Boulder (Mount et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Technical Note: Formal blind intercomparison of OH measurements: results from the international campaign HOxComp

Schlosser¹,

Brauers²,

Dorn³

et al. 2009

Atmos. Chem. Phys.

104

154

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Abstract. Hydroxyl radicals (OH) are the major oxidizing species in the troposphere. Because of their central importance, absolute measurements of their concentrations are needed to validate chemical mechanisms of atmospheric models. The extremely low and highly variable concentrations in the troposphere, however, make measurements of OH difficult. Three techniques are currently used worldwide for tropospheric observations of OH after about 30 years of technical developments: Differential Optical Laser Absorption Spectroscopy (DOAS), Laser-Induced Fluorescence Spectroscopy (LIF), and Chemical Ionisation Mass Spectrometry (CIMS). Even though many measurement campaigns with OH data were published, the question of accuracy and precision is still under discussion.Here, we report results of the first formal, blind intercomparison of these techniques. Six OH instruments (4 LIF, 1 CIMS, 1 DOAS) participated successfully in the ground-based, international HOxComp campaign carried out in Jülich, Germany, in summer 2005. Comparisons were performed for three days in ambient air (3 LIF, 1 CIMS) and for six days in the atmosphere simulation chamber SAPHIR (3 LIF, 1 DOAS). All instruments were found to measure tropospheric OH concentrations with high sensitivity and good time resolution. The pairwise correlations between different data sets were linear and yielded high correlation coefficients (r 2 =0.75−0.96). Excellent absolute agreement wasCorrespondence to: H.-P. Dorn (h.p.dorn@fz-juelich.de) observed for the instruments at the SAPHIR chamber, yielding slopes between 1.01 and 1.13 in the linear regressions. In ambient air, the slopes deviated from unity by factors of 1.06 to 1.69, which can partly be explained by the stated instrumental accuracies. In addition, sampling inhomogeneities and calibration problems have apparently contributed to the discrepancies. The absolute intercepts of the linear regressions did not exceed 0.6×10 6 cm −3 , mostly being insignificant and of minor importance for daytime observations of OH. No relevant interferences with respect to ozone, water vapour, NO x and peroxy radicals could be detected. The HOxComp campaign has demonstrated that OH can be measured reasonably well by current instruments, but also that there is still room for improvement of calibrations.

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OH ‐ Radicals in the lower troposphere

Cited by 177 publications

References 13 publications

Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006–2009

Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006–2009

OH clock determination by proton transfer reaction mass spectrometry at an environmental chamber

Technical Note: Formal blind intercomparison of OH measurements: results from the international campaign HOxComp

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