Analysis of the chemical kinetic mechanisms of ozone depletion and halogen release in the polar troposphere based on numerical modeling and field observation
Final Report Abstract
In this project, ozone depletion events and BrO vertical column densities in the Arctic spring were investigated. Early in the project, the potential of ODEs to oscillate was confirmed and researched with an extensive parameter study. Two pathways of replenishing ozone after an ODE were investigated, transport of ozone-rich air from aloft and NOx-catalyzed ozone production. Both pathways were found to be suitable to drive the oscillations, but NOx-catalyzed ozone production allowed for shorter oscillation periods of as low as five days. The state-of-theart, regional 3D model WRF-Chem was used to predict meteorology and chemistry in the Arctic springs of 2009 and 2019. The results were compared to in-situ observation, ozone sonde flights as well as GOME-2 and TROPOMI satellite BrO VCDs produced as part of this and the preceding project. For this, the retrieval algorithm for tropospheric BrO VCDs was updated extensively to fit the improved instrument specifications of TROPOMI. WRF-Chem was extended to treat halogen chemistry and a bromine emission scheme was added. For the 2009 study, infinite bromide in the snow was assumed. Different strengths of the bromine emissions were tested. The inclusion of halogen chemistry strongly increased the agreement with the observations, from a correlation at Utqiagvik of -0.31 to 0.64 for the best simulation. Assuming 50% faster emissions than the base case improved the results somewhat. In late spring, the model frequently overestimates BrO VCDs. For the 2019 study, a new finite bromide scheme was developed and implemented into WRF-Chem. The new scheme improved the agreement with the observations considerably, increasing the correlation at Utqiagvik from 0.66 to 0.81 for the whole simulation and from 0.35 to 0.75 for April only. Almost all BrO VCDs found with the TROPOMI satellite were captured by the model, however the model frequently predicts BrO VCDs near Hudson and Baffin Bay and large-scale BrO VCDs of a few 1013 molec/cm2 not observed by satellite, which can be improved in future studies.
Publications
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On the contribution of chemical oscillations to ozone depletion events in the polar spring, Atmospheric Chemistry and Physics 19, 10 161–10 190, 2019
Herrmann, M., Cao, L., Sihler, H., Platt, U., and Gutheil, E.
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Modellierung des troposphärischen Ozonabbaus im arktischen Frühling. Universität Heidelberg, Dissertation, 22. Januar 2021
Herrmann, Maximilian M.
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Numerical Simulation of Tropospheric Ozone Depletion Events in the Arctic Spring of the Year 2019, Proceedings of the 7th bwHPC Symposium, November 8, 2021, Ulm
Herrmann, M., Gutheil, E.
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Time-dependent 3D simulations of tropospheric ozone depletion events in the Arctic spring using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), Atmospheric Chemistry and Physics 21, 7611–7638, 2021
Herrmann, M., Sihler, H., Frieß, U., Wagner, T., Platt, U., and Gutheil, E.
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Ozone depletion events in the Arctic spring of 2019: A new modeling approach to bromine emissions, Atmospheric Chemistry and Physics, 2022, (acp- 2022-334)
Herrmann, M., Schöne, M., Borger, C., Warnach, S., Wagner, T., Platt, U., and Gutheil, E.
