Isoprene is a reactive gas emitted in large quantities by dense broadleaf trees in the tropics and Southeast US.[2] Isoprene undergoes chemical processing in the atmosphere to form aerosols (termed secondary organic aerosols, or SOA). SOA contributes to fine particles suspended in the atmosphere (PM2.5). PM2.5 penetrates deep into our lungs, and so isoprene affects human health.[3]

Isoprene requires existing aerosol to form SOA.[4-6] The type and properties of these pre-existing aerosols determines how much isoprene SOA forms. Laboratory experiments conducted in the U. North Carolina, Chapel Hill environmental chamber and flow reactor shows that certain anthropogenic pollutants coat the surface of pre-existing aerosols and limit the amount of isoprene SOA that forms.[6,7] This is illustrated in Figure below.

Parts of the world like Europe, the US, China, and India are cleaning up their air through strict controls on pollution sources, leading to a decrease in concentrations of anthropogenic pollutants. This may actually increase the contribution of isoprene to PM2.5, as there are fewer molecules present to form a barrier between the gas and aerosol phases.

Change in ability to form aerosols from isoprene due to presence of anthropogenic pollution.


The PhD student will apply experimental results from chamber and flow reactor experiments to a detailed 3D atmospheric chemistry model to determine the global importance of anthropogenic-biogenic interactions, evaluate model results against a long record (1991-2017) of surface observations, predict future air quality in the tropics, and offer suggestions for effective air quality policy.

We will work with the selected PhD student to identify funding for the student to spend 6-8 months in Jason Surratt’s research group at U. North Carolina, Chapel Hill to gain experimental experience and training in understanding how anthropogenic-biogenic interactions affect SOA formation.

We will also seek travel funding for the student to gain additional international experience in Daniel Jacob’s atmospheric chemistry modelling group at Harvard University. There the student will have access to a dynamic group of researchers, programmers, and software developers to gain additional skills in these areas.

The remainder of the PhD will be spent at U. Birmingham integrating experimental results in the GEOS-Chem model, interpreting model output, and evaluating against surface observations.


Training and Skills

CENTA students are required to complete 45 days training throughout their PhD, including a 10-day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills to master classes specific to the student's projects and themes. 

The PhD student will be trained in computer programming and data analysis via the following training programmes:

  • GEOS-Chem User’s Meetings in Edinburgh (September 2018) and Cambridge, MA (May 2019). Training will include the use of the model and support software to process and visualise output from the model.
  • Local (U. Birmingham) IT (Linux, Unix, R, Fortran), literature search (ISI Web of Science) and citation management (EndNote) workshops.
  • National Center for Atmospheric Sciences (NCAS) computer modelling and field measurements training workshops.


Year 1:

Extensive literature review

CENTA skills training

Residency in Surratt research group

Initial computer modelling training

Attend UK-based GEOS-Chem User’s meeting

Year 2:

Specialist training in computer modelling and programming

Integrate experimental results in GEOS-Chem

Attend US-based GEOS-Chem User’s meeting

Residency in Jacob research group

Search for evidence of anthropogenic-biogenic interactions in the observational record

Year 3+:

Conduct simulation of future air quality due to rapid development in the tropics

Interpret implication of results for developing effective air quality policy

Compile thesis

Partners and collaboration (including CASE)

CASE: None identified at this stage. Environmental Consultants will be approached using established links at U. Birmingham as the project progresses.

Collaborators: Prof. Jason Surratt (http://jasonsurratt.web.unc.edu/) and his Postdoctoral Research Fellow Dr. Yue Zhang at the Gillings School of Global Public Health at UNC-Chapel Hill.


Further Details

For further details please contact:

Dr Eloïse A. Marais: e.a.marais@bham.ac.uk, School of Geography, Earth and Environmental Sciences, http://maraisresearchgroup.co.uk/.