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Measuring the atmospheric particles which make ice in clouds and climate projections uncertain


Project Description

The formation of ice in clouds is one of the least well understood aspects of the planet’s climate system. Special aerosol particles, known as ice-nucleating particles (INPs), are needed to trigger ice formation and once ice crystals form a cascade of processes triggers precipitation and leads to dramatic changes in cloud coverage and cloud reflectivity. In fact, many clouds are extremely sensitive to ice formation and the representation of cold clouds is of first order importance for climate projections.

However, the sources, characteristics and distribution around the globe of atmospheric ice nucleating particles is extremely poorly understood. From measurements we have already conducted we know that there is a variable and sometimes very strong source of INP associated with the biology in the terrestrial mid latitude environments, but we do not know what these sources are.

The aim of this PhD project is to determine the sources of atmospheric ice nucleating particles in the vegetated North Western European region. The key development which allows this project to be possible is the development of new technology in the Ice Nucleation Group in Leeds. In particular, we have developed the Portable expansion chamber for Ice Nucleating particles mEasurement (PINE) which is the first instrument capable of running on a long-term basis, producing INP measurements on a short time resolution. This instrument was developed with our Partners in Karlsruhe Institute of Technology. You will learn to run this instrument and work with the PINE team to analyse and interpret the data. In addition, you will perform more traditional ice nucleation experiments in order to quantify the ice nucleating ability of potential sources of INP.

Objectives
The overarching aim of this project is define the sources of atmospheric ice nucleating particles in the vegetated North Western European region. This will involve:
1. Learning to operate and running the new PINE chamber INP counter, a state of the art instrument for quantifying atmospheric ice nucleating particles. This will be done at the new University of Leeds Atmospheric Observatory which is situated in the countryside between Leeds and York. This will allow one of the first ever long term (multi-year) measurements of atmospheric INP with 5 minute time resolution anywhere in the world. This first part of the project will benefit from a new grant from the European Research Council and a post-doc will be employed to set up and run the system until spring 2021.
2. Analyse the results from this unprecedented time series of INP concentrations using source apportionment modelling to identify source regions and drivers. We know that there are sources associated with plants, soils and water bodies, but do not know how effective these sources are at releasing INP into the atmosphere.
3. Use the knowledge gained from part 1 and 2 to take samples from the suspect source regions in order to do a suite of laboratory based experiments using our more traditional ice nucleation assays.
4. It should also be borne in mind that opportunities will arise for the student to shape the course of their own PhD, and we regularly have opportunities to work with partners around the world at atmospheric observatories, on ships and on aircraft.

Funding Notes

This 3.5 years NERC DTP award will provide tuition fees (£4,500 for 2019/20), tax-free stipend at the UK research council rate (£15,009 for 2019/20), and a research training and support grant of £7,000.

References

Atkinson, J. D., and Co-authors, 2013: The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds. Nature, 498, 355-358.
Murray, B. J., D. O'Sullivan, J. D. Atkinson, and M. E. Webb, 2012: Ice nucleation by particles immersed in supercooled cloud droplets. Chem. Soc. Rev., 41, 6519-6554.
Tan, I., Storelvmo, T., and Zelinka, M. D., 2016: Observational constraints on mixed-phase clouds imply higher climate sensitivity, Science, 352, 224-227, 10.1126/science.aad5300.
O’Sullivan D, and Co-authors, 2018: Contributions of biogenic material to the atmospheric ice-nucleating particle population in North Western Europe. Scientific Reports, 13821.

How good is research at University of Leeds in Earth Systems and Environmental Sciences?

FTE Category A staff submitted: 79.20

Research output data provided by the Research Excellence Framework (REF)

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