Multiphase modelling of atmospheric chemistry

This project will explore a new representation of multiphase atmospheric chemistry in a state-of-the-art chemical transport model, thus improving our ability to predict climate change and air quality.

Atmospheric chemistry is central to many critical environmental challenges such as climate change, air pollution, stratospheric ozone loss and ecosystem degradation. Numerical models are used to assess our scientific knowledge and turn it into policy relevant understanding. Although much of this chemistry occurs in the gas phase, critical elements occur in or on other phases such as within aerosols or clouds. Historically these multi-phase components have been represented through relatively simple parameterizations where one gas phase chemical is turned into another gas phase chemical at a rate determined by the surface area of the other phase and its composition. This has avoided the need to represent the concentration of chemicals within the aerosol or cloud but has led to an inability to represent some of the complexities of the chemistry. It is now becoming apparent that this simple approach is reaching its limit and a more complete representation of the chemistry occurring within clouds and aerosols is required. This project will implement a laboratory constrained multiphase chemistry into the GEOS-Chem (www.geos-chem.org) model of atmospheric chemistry and transport and explore its benefits and disadvantages over a more conventional approach.

The initial focus of the project will be on the representation of tropospheric multiphase halogen (Cl, Br and I). The Wolfson Atmospheric Chemistry Laboratories (WACL) has an international reputation for understanding the impact of halogens on tropospheric chemistry from a field, laboratory and modelling perspective, with a slew of high-profile papers on the topic recently. This project will extend our understanding from a numerical modelling perspective. Initial steps will be to collate from the literature the rate constants for aqueous and aerosol phase reactions for halogen species, and the transfer rates between the gas and aerosol phase. Then these rate constants will be implemented into the GEOS-Chem model and the impacts on the composition of the atmosphere investigated. The predictions of the model will be compared to field observations to assess the model’s performance. Finally, the implications for both air quality and climate change will be assessed.

The ideal candidate for this project will have an understanding of atmospheric chemistry and an interest in computational modelling, however, suitable candidates with other strengths would also be able to make a success of the project, given the training that is available from WACL, the University of York’s Chemistry department and the PANORAMA DTP.

More details of the project can be found on the NERC PANORAMA DTP web page (panorama-dtp.ac.uk).

The Leeds-York Natural Environment Research Council (NERC) PANORAMA Doctoral Training partnership (DTP) has a comprehensive programme of researcher training covering subject-specific and generic skills. Students will obtain some training and understanding of the full range of training topics. All new students are required to make a training plan when they start their PhD. Training courses are split into ‘nodes’ covering different aspects of your PhD, much of the training in transferable skills will be provided centrally by the Staff and Departmental Development Unit (SDDU) at Leeds and the equivalent service at York (Skills Forge). Inductions and training on specific lab instruments and techniques will be provided by individual labs/departments as required by each student.
Additionally, all Chemistry research students have access to our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills.

The Department of Chemistry holds an Athena SWAN Gold Award and is committed to supporting equality and diversity for all staff and students. The Department strives to provide a working environment which allows all staff and students to contribute fully, to flourish, and to excel: https://www.york.ac.uk/chemistry/ed/. This PhD project is available to study full-time or part-time (50%).
This PhD will formally start on 1 October 2020. Induction activities will start on 28 September.

You will be based in the Department of Chemistry at the University of York.