TY  - JOUR
AU  - Fuchs, Hendrik
AU  - Novelli, Anna
AU  - Rolletter, Michael
AU  - Hofzumahaus, Andreas
AU  - Pfannerstill, Eva Y.
AU  - Kessel, Stephan
AU  - Edtbauer, Achim
AU  - Williams, Jonathan
AU  - Michoud, Vincent
AU  - Dusanter, Sebastien
AU  - Locoge, Nadine
AU  - Zannoni, Nora
AU  - Gros, Valerie
AU  - Truong, Francois
AU  - Sarda-Esteve, Roland
AU  - Cryer, Danny R.
AU  - Brumby, Charlotte A.
AU  - Whalley, Lisa K.
AU  - Stone, Daniel
AU  - Seakins, Paul W.
AU  - Heard, Dwayne E.
AU  - Schoemaecker, Coralie
AU  - Blocquet, Marion
AU  - Coudert, Sebastien
AU  - Batut, Sebastien
AU  - Fittschen, Christa
AU  - Thames, Alexander B.
AU  - Brune, William H.
AU  - Ernest, Cheryl
AU  - Harder, Hartwig
AU  - Muller, Jenifer B. A.
AU  - Elste, Thomas
AU  - Kubistin, Dagmar
AU  - Andres, Stefanie
AU  - Bohn, Birger
AU  - Hohaus, Thorsten
AU  - Holland, Frank
AU  - Li, Xin
AU  - Rohrer, Franz
AU  - Kiendler-Scharr, Astrid
AU  - Tillmann, Ralf
AU  - Wegener, Robert
AU  - Yu, Zhujun
AU  - Zou, Qi
AU  - Wahner, Andreas
TI  - Comparison of OH reactivity measurements in the atmospheric simulation chamber SAPHIR
JO  - Atmospheric measurement techniques discussions
VL  -  231
SN  - 1867-8610
CY  - Katlenburg-Lindau
PB  - Copernicus
M1  - FZJ-2017-05325
SP  - 1 - 56
PY  - 2017
AB  - Hydroxyl (OH) radical reactivity (kOH) has been measured for 18 years with different measurement techniques. In order to compare the performances of instruments deployed in the field, two campaigns were conducted performing experiments in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich in October 2015 and April 2016. Chemical conditions were chosen either to be representative of the atmosphere or to test potential limitations of instruments. All types of instruments that are currently used for atmospheric measurements took part in one of the two campaigns. The results of these campaigns demonstrate that OH reactivity can be accurately measured for a wide range of atmospherically relevant chemical conditions (e.g. water vapor, nitrogen oxides, various organic compounds) by all instruments. The precision of the measurements (limit of detection < 1 s−1 at a time resolution of 30 seconds to a few minutes) is higher for instruments directly detecting hydroxyl radicals, whereas the indirect Comparative Reactivity Method (CRM) has a higher limit of detection of 2 s−1 at a time resolution of 10 to 15 min. The performances of the instruments were systematically tested by stepwise increasing, for example, the concentrations of carbon monoxide (CO), water vapor or nitric oxide (NO). In further experiments, mixtures of organic reactants were injected in the chamber to simulate urban and forested environments. Overall, the results show that instruments are capable of measuring OH reactivity in the presence of CO, alkanes, alkenes and aromatic compounds. The transmission efficiency in Teflon inlet lines could have introduced systematic errors in measurements for low-volatile organic compounds in some instruments. CRM instruments exhibited a larger scatter in the data compared to the other instruments. The largest differences to reference measurements or to calculated reactivity were observed by CRM instruments in the presence of terpenes and oxygenated organic compounds (mixing ratio of OH reactants were up to 10 ppbv). In some of these experiments, only a small fraction of the reactivity is detected. The accuracy of CRM measurements is most likely limited by the corrections that need to be applied in order to account for known effects of, for example, deviations from pseudo-first order conditions, nitrogen oxides or water vapor on the measurement. Methods to derive these corrections vary among the different CRM instruments. Measurements by a flow-tube instrument combined with the direct detection of OH by chemical ionization mass spectrometry (CIMS) show limitations in cases of high reactivity and high NO concentrations, but were accurate for low reactivity (< 15 s−1) and low NO (< 5 ppbv) conditions.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.5194/amt-2017-231
UR  - https://juser.fz-juelich.de/record/836204
ER  -