The aim of this PhD project is to understand how ice-nucleating particles in the atmosphere affect clouds and climate. The formation of ice in clouds is one of the least well-understood aspects of the Earth’s climate system. Recent advances in computer models, laboratory measurements and satellite observations now enable the effects of ice formation on the climate system to be explored in detail. The project will use a combination of the latest laboratory measurements of ice-nucleating particles, new field measurements, high-resolution model simulations, global climate model simulations and satellite observations.
The project will involve:
i) Understanding the global distribution of ice-nucleating particles. These are rare particles (around one in a million) that can induce ice formation in cloud droplets. The research will involve collating measurement data from around the world in order to identify regions where we are missing important particle sources in an advanced global model. The aim is to improve global model simulations with a view to incorporating these particles in climate simulations.
ii) Simulating the response of clouds to changes in ice-nucleating particles. You will use an advanced meteorological model of clouds (based on the Met Office forecast model) to simulate how different types of clouds (e.g., deep convection, Arctic clouds or cyclones) respond to changes in ice-nucleating particles. Simulations will be evaluated against satellite and other data.
iii) Exploring the potential implications for climate. You will work with researchers at the Met Office using your results to understand how best to simulate ice-nucleating particles and their effects on a global scale in a future version of the UK’s climate model.
Previous collaborative PhD research by this group of supervisors led to the discovery of how very low concentrations of ice-nucleating particles over the Southern Ocean can explain large climate model errors (Vergara-Temprado et al., 2018). The aim of this project is to extend the research to other cloud types and environments to understand how ice-nucleating particle concentrations influence cloud properties and climate.
Atkinson, J. D., and Coauthors, 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.
Wilson, T. W., and Coauthors, 2015: A marine biogenic source of atmospheric ice-nucleating particles. Nature, 525, 234-238.
Vergara-Temprado, J., Murray, B. J., Wilson, T. W., O'Sullivan, D., Browse, J., Pringle, K. J., Ardon-Dryer, K., Bertram, A. K., Burrows, S. M., Ceburnis, D., DeMott, P. J., Mason, R. H., O'Dowd, C. D., Rinaldi, M., and Carslaw, K. S.: Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations, Atmos. Chem. Phys., 17, 3637-3658, 2017.
Vergara-Temprado J, Miltenberger AK, Furtado K, Grosvenor DP, Shipway BJ, Hill AA, Wilkinson JM, Field PR, Murray BJ, Carslaw KS. 2018. Strong control of Southern Ocean cloud reflectivity by ice-nucleating particles. Proceedings of the National Academy of Sciences of the United States of America. 115(11), pp. 2687-2692.