Measurements of tropospheric OH concentrations: A comparison of field data with model predictions

Perner, D.; Platt, U.; Trainer, M.; Hübler, G.; Drummond, J.; Junkermann, W.; Rudolph, J.; Schubert, Brian A.; Völz, Andreas; Ehhalt, D. H.; Rumpel, K.-J.; Helas, G.

doi:10.1007/bf00048859

Cited by 118 publications

(52 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ambient measurement of OH is therefore a good test of proposed chemical mechanisms postulating the importance of chemical species and/or processes in the atmosphere. The OH radical is usually measured in the field with one of three techniques: differential optical absorption spectroscopy (DOAS; Perner et al, 1987) via absorption of light by OH, chemical ionisation mass spectrometry (CIMS; Eisele and Tanner, 1991) via the detection of H 2 SO 4 after the oxidation of SO 2 by atmospheric OH, and laser-induced fluorescence (LIF-FAGE;Hard et al, 1984) via the detection of OH radical fluorescence after laser excitation. Several comparison campaigns have been performed, both on ground (Hofzumahaus et al, 1998;Schlosser et al, 2007) and aircraft (Eisele et al, 2001;Ren et al, 2012), to test the consistency and performance of the different techniques and have generally shown good agreement.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of an inlet pre-injector laser-induced fluorescence instrument for the measurement of atmospheric hydroxyl radicals

et al. 2014

View full text Add to dashboard Cite

Abstract. Atmospheric measurements of hydroxyl radicals (OH) are challenging due to a high reactivity and consequently low concentration. The importance of OH as an atmospheric oxidant has motivated a sustained effort leading to the development of a number of highly sensitive analytical techniques. Recent work has indicated that the laser-induced fluorescence of the OH molecules method based on the fluorescence assay by gas expansion technique (LIF-FAGE) for the measurement of atmospheric OH in some environments may be influenced by artificial OH generated within the instrument, and a chemical method to remove this interference was implemented in a LIF-FAGE system by . While it is not clear whether other LIF-FAGE instruments suffer from the same interference, we have applied this method to our LIF-FAGE HORUS (Hydroxyl Radical Measurement Unit based on fluorescence Spectroscopy) system, and developed and deployed an inlet pre-injector (IPI) to determine the chemical zero level in the instrument via scavenging the ambient OH radical.We describe and characterise this technique in addition to its application at field sites in forested locations in Finland, Spain and Germany. Ambient measurements show that OH generated within the HORUS instrument is a non-negligible fraction of the total OH signal, which can comprise 30 to 80 % during daytime and 60 to 100 % during the night. The contribution of the background OH varied greatly between measurement sites and was likely related to the type and concentration of volatile organic compounds (VOCs) present at each particular location. Two inter-comparisons in contrasting environments between the HORUS instrument and two different chemical ionisation mass spectrometers (CIMS) are described to demonstrate the efficacy of IPI and the necessity of the chemical zeroing method for our LIF-FAGE instrument in such environments.

show abstract

Section: Introductionmentioning

confidence: 99%

Characterisation of an inlet pre-injector laser-induced fluorescence instrument for the measurement of atmospheric hydroxyl radicals

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Since the first successful measurement of tropospheric OH radicals by long-path laser absorption in the early 1980s (Perner et al, 1987) several instruments based on different detection principles were developed (for an overview see Crosley, 1994). Among those only the spectroscopic detection of OH by long-path laser absorption provides absolutely calibrated OH measurements.…”

Section: Introductionmentioning

confidence: 99%

In-situ Measurements of Tropospheric Hydroxyl Radicals by Folded Long-Path Laser Absorption During the Field Campaign POPCORN

Brandenburger¹,

Brauers²,

Dorn³

et al. 1998

Atmospheric Measurements During POPCORN — Characterisation of the Photochemistry Over a Rural Area

View full text Add to dashboard Cite

Abstract. Absolutely calibrated in-situ measurements of tropospheric hydroxyl radicals, formaldehyde, sulfur dioxide, and naphthalene (C 10 H 8 ) were performed by long-path laser absorption spectroscopy during the field campaign POPCORN. The absorption light path was folded into an open optical multiple reflection cell with a mirror separation of 38.5 m. Using a light path length of 1848 m and an integration time of 200 s, the average 1σ -detection limits of OH, HCHO, SO 2 and C 10 H 8 during POPCORN were 8.7·10 5 cm −3 , 8.3 ·10 9 cm −3 , 2.4 ·10 9 cm −3 , 1.5 ·10 8 cm −3 , respectively. In total, 392 identifications of OH in air spectra were made in a rural environment between August 5 and August 23, 1994. We present and discuss OH absorption spectra and diurnal OH concentration profiles of three days which are representative for measurements under different pollution conditions during POPCORN. The observed maximum and median OH radical concentrations are 1.3 ·10 7 OH/cm 3 and 4.0 ·10 6 OH/cm 3 , respectively. The measured diurnal variation of the OH concentration shows a good correlation with the primary formation reaction of OH radicals which is the photolysis of ambient ozone. Deviations from this correlation in the morning and evening hours, when the OH concentration is higher than expected from the ozone photolysis, demonstrate the importance of other photochemical HO x production pathways during POPCORN.

show abstract

“…Initial attempts to measure atmospheric OH by DOAS were successful, but required very long absorption path lengths (10 km) and long integration times of about 1 h (Perner et al, 1987;Platt et al, 1988). Attempts in the 1970s and 1980s to measure atmospheric OH by LIF and the radiocarbon tracer method failed as a result of insufficient detection sensitivity, poor technical performance or interference problems.…”

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.

105

148

View full text Add to dashboard Cite

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.

show abstract

Measurements of tropospheric OH concentrations: A comparison of field data with model predictions

Cited by 118 publications

References 32 publications

Characterisation of an inlet pre-injector laser-induced fluorescence instrument for the measurement of atmospheric hydroxyl radicals

Characterisation of an inlet pre-injector laser-induced fluorescence instrument for the measurement of atmospheric hydroxyl radicals

In-situ Measurements of Tropospheric Hydroxyl Radicals by Folded Long-Path Laser Absorption During the Field Campaign POPCORN

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

Contact Info

Product

Resources

About