The Size, Sources and Transport of the Seeds of Ice in Clouds

Abstract:
It is well known that the formation of ice in a cloud can influence many of its properties from its reflectivity to its longevity it the atmosphere. Given this, the presence of ice-nucleating particles (INPs) in clouds can have a significant impact on individual clouds and on climate as a whole. However, currently, little is known about the origins, the abundance and the transportation of these particles in the atmosphere. Doubtless, understanding the size and distribution of INP in the atmosphere would help to deepen our understanding of their lifetimes, but few studies have examined this aspect of cloud formation. Furthermore, improving understanding of INPs in the atmosphere will help to inform climate models due to the uncertainty in the cloud radiative effect and how this may change with future warming.
Given this, the proposed project will aim to investigate the size, sources and transport of INPs in the atmosphere by utilising the newly developed SHARK (Selective Height Aerosol Research Kit). The SHARK will be used to collect size resolved aerosol for offline INP analysis by using cascade impactors to separate the aerosol sample into different size bins. This radio-controlled payload has been designed to be attached to a tethered balloon, allowing the collection of aerosol particles from much higher altitudes without the use of aircraft. The aim of this is to investigate size distribution of INP at different locations and at different altitudes, to examine the different sources of INPs and investigate whether they are transported to atmospherically relevant altitudes for cloud formation. The collected aerosol samples will be analysed using off-line droplet freezing techniques to determine the size resolved INP concentrations and active ice fractions. Then, further analysis will be required to get a better understanding of the source and composition of the INP. Scanning electron microscopy (SEM) will be used to examine the morphology of the aerosols collected and energy dispersive X-ray spectroscopy (EXD) will be used to examine their chemical composition.

Aerosol science has a significant impact on a broad range of disciplines, extending from inhaled drug delivery, to combustion science and its health impacts, aerosol assisted routes to materials, climate change, and the delivery of agricultural and consumer products. Estimates of the global aerosol market size suggest it will reach $84 billion/year by 2024 with products in the personal care, household, automotive, food, paints and medical sectors. Air pollution leads to an estimated 30-40,000 premature deaths each year in the UK, and aerosols transmit human and animal infections. More than 12 million people in the UK live with lung disease such as asthma, and the NHS spends ~£5 billion/year on respiratory therapies. Many of the technological, societal and health challenges central to these areas rely on core skills and knowledge of aerosol science. Despite this, an Industrial Workshop and online survey (held in preparation for this bid) highlighted the current doctoral skills gap in aerosol science in the UK. Participating industries reported that only 15% of their employees working with aerosol science at doctoral-level having received any formal training. A CDT in aerosol science, CAS, will fill this skills gap, impacting on all areas of science where core training in aerosol science is crucial.

Impact on the UK aerosol community: Aerosol scientists work across governmental policy, industrial research and innovation, and in academia. Despite the considerable overlap in training needs for researchers working in these diverse sectors, current doctoral training in aerosol science is fragmentary and ad hoc (e.g. the annual Fundamentals of Aerosol Science course delivered by the Aerosol Society). In addition, training occurs within the context of individual disciplines, reinforcing artificial subject boundaries. CAS will bring coherence to training in the core physical and engineering science of aerosols, catalysing new synergies in research, and providing a focal point for training a multidisciplinary community of researchers. Working with the Aerosol Society, we will establish a legacy by providing training resources for future researchers through an online training portal.

Impact on industry and public-sector partners: 45 organisations have indicated they will act as CAS partners with interests in respiratory therapies, public health, materials manufacturing, consumer and agricultural products, instrumentation, emissions and environment. Establishing CAS will deliver researchers with the necessary skills to ensure the UK establishes and sustains a scientific and technical lead in their sectors. Further, it will provide an ideal mechanism for delivering Continuing Professional Development for the existing workforce practitioners. The activity of CAS is aligned to the Industrial Strategy Challenge Fund (e.g. through developing new healthcare technologies and new materials) and the EPSRC Prosperity Outcomes of a productive, healthy (e.g. novel treatments for respiratory disease) and resilient (e.g. adaptations to climate change, air quality) nation, with both the skilled researchers and their science naturally translating to long-lasting impact. Additionally, rigorous training in responsible innovation and ethical standards will lead to aerosol researchers able to contribute to developing: regulatory standards for medicines; policy on air quality and climate geoengineering; and regulations on manufactured nano-materials.

Public engagement: CAS will provide a focal point for engaging the public on topics in aerosol science that affect our daily lives (consumer products, materials) through to our health (inhalation therapeutics, disease transmission and impacts of pollution) and the future of our planet (geoengineering). Supported by a rigorous doctoral level training in aerosol science, this next generation of researchers will be ideally positioned to lead debates on all of these societal and technological challenges.