EGU21-2344, updated on 29 Aug 2022
https://doi.org/10.5194/egusphere-egu21-2344
EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Experimental budgets of OH, HO2 and RO2 radicals during the JULIAC 2019 campaign

Changmin Cho1, Andreas Hofzumahaus1, Hendrik Fuchs1, Frank Holland1, Birger Bohn1, William J. Bloss2, Hans-Peter Dorn1, Marvin Glowania2, Torsten Hohaus1, Liu Lu1, Chandrakiran Lakshmisha1, Doreen Niether1, Paul S. Monks3, David Reimer1, Franz Rohrer1, Roberto Sommariva2,3, Zhaofeng Tan1, Ralf Tillmann1, Astrid Kiendler-Scharr1, and Andreas Wahner1
Changmin Cho et al.
  • 1Forschungszentrum Jülich, Institute for Energy and Climate Research: Troposphere (IEK-8), Jülich, Germany
  • 2School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
  • 3Department of Chemistry, University of Leicester, Leicester, UK

The Jülich Atmospheric Chemistry Project campaign (JULIAC) was performed using the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich (FZJ), Germany. Ambient air was continuously drawn into the chamber through a 50m high inlet line for one month in each season throughout 2019. The residence time of air inside the chamber was one hour. As the sampling point is surrounded by a mixed deciduous forest and is located close to a small–size city (Jülich), the sampled air was influenced by both anthropogenic and biogenic emissions. Measurements included hydroxyl radical (OH) achieved by laser induced fluorescence (LIF) instrument that implemented a newly implemented chemical modulation reactor (CMR) and by differential optical absorption spectroscopy (DOAS). Measurement of both instruments were in good agreement within about 10% and showed no evidence of unknown OH interferences. In addition to OH, hydroxyl and peroxy radicals (HO2 and RO2, respectively), and OH reactivity (kOH, inverse of the OH lifetime) were measured together with a comprehensive set of trace gases concentrations and aerosol properties, allowing for the investigation of the seasonal and diurnal variation of atmospheric oxidant concentrations and their roles in the degradation of volatile organic compounds (VOCs) and contribution to secondary pollutants (ozone and particles).

The experimental budget analyses of OH, HO2, RO2, and ROx radical production and destruction rate will be presented for the campaigns in spring and summer (April and August). For most conditions, the concentrations of radicals were sustained by regeneration of HO2 and RO2 radicals via reactions with nitric oxide (NO). The highest radical turnover rates of up to 17 ppbv·hr-1 was observed during a heat wave period in August. For NO levels below 1ppbv, the budget shows a missing OH radical source up to 4 ppbv h-1, while HO2 and RO2 productionand destruction rates were balanced. Above 2 ppbv of NO, missing HO2 production and RO2 loss paths with rates of up to 5 ppbv h-1 were found. In addition, the dataset allows for a detail examination of the importance of radical production and destruction processes from isomerization reactions, HO2 uptake on aerosol, chlorine nitrate chemistry.

How to cite: Cho, C., Hofzumahaus, A., Fuchs, H., Holland, F., Bohn, B., Bloss, W. J., Dorn, H.-P., Glowania, M., Hohaus, T., Lu, L., Lakshmisha, C., Niether, D., Monks, P. S., Reimer, D., Rohrer, F., Sommariva, R., Tan, Z., Tillmann, R., Kiendler-Scharr, A., and Wahner, A.: Experimental budgets of OH, HO2 and RO2 radicals during the JULIAC 2019 campaign, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2344, https://doi.org/10.5194/egusphere-egu21-2344, 2021.

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