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Identifying the drivers of biogenic ice nucleating particles emissions from an agricultural site

Dr Daniel O'Sullivan and Dr Ben Murray

In the absence of airborne particles which can catalyse (or nucleate) ice, cloud water droplets will remain liquid down to about -37°C. This fundamental property of water governs when rain and snow forms, and regulates cloud properties such as lifetime, extent and interaction with radiation. While biological aerosols such as bacteria or biogenic matter in soil dusts and sea spray have all been implicated as important ice nucleating particles (INPs) in our atmosphere, there is currently a major shortfall in the field measurements required to predict their impacts on cloud ice formation. By participating in a field campaign and subsequent data analysis, the chosen student will be contributing to efforts to narrowing the currently large uncertainties on the impacts of INP emissions on both weather and climate.

As part of the drive to constrain the dominant sources of INPs, we are constructing the world’s first mobile laboratory for ice nucleation research (IcePod). A field site representative of an important source of highly efficient INPs has been chosen to deploy the laboratory during the summer; an agricultural research station operated by the University of Leeds. The student will work closely with researchers in the deployment of the IcePod during this campaign. The goal of the deployment is to highlight which factors drive emissions of biological INPs, such as windspeed, rainfall, relative humidity and human activities such as harvesting. Specifically, the holder will take part in ambient aerosol sampling and characterization (e.g. size, chemical composition and ice nucleating properties). In addition, the intern will facilitate with the data analysis and interpretation, with an emphasis on uncovering the main drivers of biogenic ice nucleating particle emissions at the agricultural site.

During their 8 to 10 week placement, the scholar will work together with research staff in the Ice Nucleation group at Leeds, and will receive training in the sampling and analysis techniques used to examine the ice nucleating properties of atmospheric aerosol. In addition to developing their understandings of aerosol science, the scholar will gain experience in the logistical preparations and operations of atmospheric field campaigns, and develop the skills required to contribute effectively to a collaborative research team. Training, mentorship and project supervision for the intern will be provided throughout by Dr. O’Sullivan and Dr. Ben Murray. Our previous undergraduate placements have led to numerous peer reviewed publications with the Ice Nucleation group at Leeds, and we continue our commitment to facilitating the development of aspiring researchers in aerosol science. The necessary physical resources for sampling and aerosol analysis is available within the Ice Nucleation group (e.g. SMPS, OPCs, ATOFMS, Ice nucleation assays and aerosol sampling systems). The IcePod mobile laboratory is to be delivered to the School in May.