Investigating the effect of atmospheric weathering on the ice nucleating ability of K-feldspar and quartz.
Prof Ben Murray
The formation of ice in supercooled water droplets in our atmosphere plays a central role in regulating important cloud properties such as cloud radiative properties and the generation of precipitation. While this process only becomes kinetically favourable at temperatures below -33C for cloud sized droplets [Herbert, 2015], certain particles, known as ice nucleating particles can catalyse the freezing process at much high temperatures [Murray, 2012]. Globally, a component of mineral dusts, K-feldspar, has been shown to be an important source of Ice Nucleating Particles (INPs) around the world [Atkinson, 2013]. While it is known that reactions of feldspar with acids modify its surface properties, the extent to which atmospheric processing of feldspars by common environmental acids (a process known as “weathering”) affects its ice nucleating abilities is largely unknown. Similarly, quartz has also been shown to be an effective INP [Harrison, 2017], and may compete with K-feldspar under certain circumstances such as when mineral dust is transported over a large distance and exposed to persistent atmospheric weathering, as quartz is expected to be less affected to weathering due to its relative chemical inertness. Given that large burden of mineral dusts in our atmosphere, understanding how this weathering process affects its ice nucleating abilities is of first order importance to improving our current knowledge of how mineral dusts contribute to the total INP loading around the globe [Vergara-Temprado, 2017].
The project goals are stated as:
- To measure the effects of atmospheric weathering on K-feldspar by measuring its “deactivation” by sulphuric acid.
- To measure the effects of atmospheric weathering on quartz by measuring its “deactivation” by sulphuric acid.
- Improve global INP models based on the results found.
During their 8 to 10 week placement, the student will work together with research staff in the Ice Nucleation group at Leeds, and will receive training in the analytical techniques used to probe the ice nucleating properties of atmospheric aerosol. In addition to developing their research, experimental and data analysis skills, the student will also be introduced to the fundamentals of aerosol science and instrumentation. Within the Ice Nucleation Group at Leeds, our previous undergraduate placements have led to numerous peer reviewed publications, and we continue our commitment to facilitating the development of aspiring researchers in aerosol science.
The successful applicant will gain hands on experience working with well-established INP detection techniques, including offline instruments (e.g. µL-NIPI) and a newly-developed online INP detection instrument, the PINE chamber. Training, mentorship and project supervision for the intern will be provided throughout by Prof. Ben Murray, Dr. Daniel O’Sullivan and Mike Adams, with further guidance also being provided by Dr Ottmar Möhler at the Karlsruhe Institute of Technology (KIT), Germany.
References
Atkinson, J., Murray, B., Woodhouse, M., Whale, T., Baustian, K., Carslaw, K., Dobbie, S., O’Sullivan, D. and Malkin, T. (2013). The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds. Nature, 498(7454), pp.355-358.
Harrison, A. et al. “The effectiveness of quartz as an ice nucleating particle”, (2015), In Prep
Herbert, Ross J. et al. "Sensitivity Of Liquid Clouds To Homogenous Freezing Parameterizations". Geophysical Research Letters 42.5 (2015): 1599-1605.
Murray, B. J. et al. "Ice Nucleation By Particles Immersed In Supercooled Cloud Droplets". Chemical Society Reviews 41.19 (2012): 6519.
Vergara-Temprado, J., Murray, B., Wilson, T., Sullivan, D., Browse, J., Pringle, K., Ardon-Dryer, K., Bertram, A., Burrows, S., Ceburnis, D., DeMott, P., Mason, R., Dowd, C., Rinaldi, M. and Carslaw, K. (2017). Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations. Atmospheric Chemistry and Physics, 17(5), pp.3637-3658.