Photochemistry of important odd nitrogen species in the mesosphere/lower thermosphere and stratosphere

• Applicant: Dr. Olexandr Lednyts`kyy
• Subject Area: Atmospheric Science
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 450225062

Strong nightglow occurs in the upper mesosphere and lower thermosphere (MLT) of the Earth‘s upper atmosphere and includes an emission layer of excited nitrogen dioxide (NO2). Excitation mechanisms contributing to excited nitrogen dioxide in the MLT and stratosphere are in focus of this project because they are not well understood. Nitrogen dioxide is also important in the stratosphere because it contributes to the ozone depletion. The odd nitrogen (N, NO, NO2) photochemistry is going to be analized in the MLT and stratosphere on the basis of global emission measurements available now. For this task, the Multiple Airglow Chemistry (MAC) model is going to be extended to consider reactions with odd oxygen and odd hydrogen. Retrievals using its current version enable considering odd oxygen (O(3P), O(1D), O3) and odd hydrogen (H, OH, HO2). The retrievals were validated on the basis of in situ rocket measure-ments carried out in the MLT. Considering previous studies investigating nitrogen dioxide emissions, the retrieval of the most important spieces of odd oxygen, odd hydrogen and odd nitrogen concentration is going to be carried out in the stratosphere using the extended version of the MAC model on the basis of new measurements. Reactions considered in the extended version of the MAC model can be adopted in a photochemical module of a general circulation model.

• DFG Programme: Research Grants
• International Connection: Canada
• Co-Investigator: Professor Christian von Savigny, Ph.D.
• Cooperation Partners: Professor Adam Bourassa, Ph.D.; Professor Douglas Degenstein, Ph.D.; Christopher Roth