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Institute of Energy and Climate Research

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Photochemistry and Radicals

Free radicals (OH, HO2, RO2 and NO3) play a central role in the chemical degradation of reactive trace gases in the atmosphere. The hydroxyl (OH) radical is primarily formed by photochemical processes under the influence of solar radiation and represents the most important atmospheric oxidant. On a global scale, it removes most (ca. 90%) of the greenhouse gas methane (CH4) and the toxic carbon monoxide (CO) from the atmosphere. In general, the chemical degradation of trace gases forms new chemical compounds, some of which belong to the group of secondary pollutants like ozone, hydroperoxides, acids, and fine particles. These products are not only relevant for air quality and health, but also influence Earth's radiation budget und thereby climate.

Our division investigates experimentally the atmospheric radical- and photochemistry by using advanced physical measurement techniques. The measurements are performed in field campaigns on the ground, on the Zeppelin NT, on the research aircraft HALO, and in the atmosphere simulation chamber SAPHIR. In addition, we perform chemical model simulations which are compared to the experimental observations, in order to improve our understanding of atmospheric chemical processes. Improved descriptions of the chemistry contribute to the development of more reliable models for the prediction of air quality and climate change.

Ongoing work and projects

    Investigation of the oxidation of important organic compounds that are emitted by plants and which influence atmospheric self-cleaning by radicals.
    Field investigation of the atmosperic chemistry of radicals and aerosols during different seasons under the influence of biogenic and anthropogenic emissions in Jülich, Germany.
  • China
    Investigation of the atmospheric self-cleaning and the formation of secondary pollutants in densely populated areas in China.
    Investigation of the radical chemistry in the lower troposphere over different regions in Europe using a Zeppelin NT as a measurement platform.
  • OMO
    Investigation of the atmospheric self-cleaning in the upper troposphere under the influence of air from South Asia during the summer monsoon.
  • HOx working group
    International cooperation aiming for improved OH, HO2 and RO2 radical measurement techniques.
  • EMeRGe
    EMeRGe HALO Mission zur Untersuchung der Ausbreitung und Umwandlung von Luftverschmutzungen von Megacities
  • HD(CP)2
    Provision of atmospheric measurement data of the supersite JOYCE for comparison with climate model data