University of Leeds: Earth, Environment & Sustainability
Supervisor: Ross Herbert R.J.Herbert @ leeds.ac.uk
Ice-nucleating particles (INPs) are a rare subset of aerosol particles that facilitate ice formation in sub-zero clouds. Their role in the climate system remains uncertain, part of which is because we still lack a full understanding of their abundances and sources across the globe.
Recently, measurements of INPs were made during a 6-month campaign at the Weybourne measurement site on the east coast of the UK. The measurements show us that the number of INPs varied depending on the wind direction. We hypothesize that the wind direction is associated with different airmasses, each of which contains different aerosol particles and INPs transported from different regions. A key part of the puzzle is establishing exactly where that air came from and help link possible aerosol and INP sources to the measurement site.
Using back-trajectory analysis with the FLEXPART model, we can pick a location at a specific time and track where the air and associated aerosols came from in the previous days to weeks. This can give us a picture of where the air most likely originated from, and what altitudes it was transported at. Linking the back-trajectory analysis to specific days in the campaign period will show us where the air came from, helping us to test our hypothesis.
Additional information measured at the Weybourne site can help us build up a complete picture of what aerosol species were acting as INPs; this includes aerosol size distributions, chemistry data, and rainfall. We can make use of satellite datasets and climate model output that we have in the research group to estimate what aerosols and INPs were being transported in the different airmasses, and whether rainfall played a role during its transport in the atmosphere.
The outcomes of this placement will provide key information alongside the INP measurements and are likely to help support a future publication of the campaign.
Ross Herbert and Eszter Kovacs will be the primary points of contact for student during the placement. Martin Daily led the measurement campaign and will provide assistance accessing and using the data collected. Professors Ben Murray and Ken Carslaw will provide additional support.
1. Learn how to set up and run the FLEXPART model on the University of Leeds’ high-performance computer AIRE and analyse the output using python (Eszter Kovacs to help).
2. Run the FLEXPART back-trajectory model and analyse the output to identify sources of airmasses influencing the Weybourne measurement site on key days during the campaign that displayed contrasting conditions.
3. Identify links between the sources of airmasses and the number of ice-nucleating particles (INPs) measured at the site.
4. If time allows, the student will compare meteorological data and aerosol size distributions from MetOffice UK Earth System Model (UKESM) simulations and satellite observations (both provided by Ross Herbert) to those measured at the site.
5. Attend a 2-day hackathon and conference focusing on aerosol and chemistry being held in Leeds (July 16-17).
6. Present results to the research group at the end of the placement.
At the end of this placement the student will gain the following skills:
Using the command line; using a supercomputer; setting up and running a complex model; analysing and visualizing data in python; using output from a global climate model; using satellite observations; hypothesis testing; presentation experience; and a deeper understanding of aerosol science and the climate.
The student will attend and take part in weekly meetings with the Ice Nucleation group and the Aerosols, Clouds, and Climate group. The student will be given a tour of the laboratories to better understand how we measure aerosols and spend time shadowing one of the researchers in the Ice Nucleation group (Jack Macklin) making INP measurements in the laboratory. Ross Herbert is co-leading a 2-day hackathon and workshop focusing on aerosols and chemistry in the UKESM that takes place on July 16-17 within the University. If the timing is appropriate the student will be invited to join us, with the possibility of producing a research poster for the event.
