This proposal aims to demonstrate an aircraft based measurement and reporting system for in situ real-time discrimination of single coarse dust, ash, super-cooled water and ice particles . The new system will incorporate new single particle polarization detector technology into an existing airborne certified single particle backscatter spectrometer that has been developed for commercial airliners. The target for the demonstrator will initially be the commercial airline industry, with a focus on contributing to civil aircraft safety and Government contingency applications, but it will also serve for global atmospheric research and monitoring applications, e.g. to assist assessment of the impact of aircraft operations on the upper troposphere-lower stratosphere region. It will also improve meteorological information currently broadcast via the World Meteorological Aircraft Meteorological Data Relay (AMDAR) system from commercial aircraft as well as the UK Science community by providing enhanced measurement capability to their research aircraft. An existing aircraft test bed, the FAAM BAe 146 research aircraft, operated jointly by the UK Meteorological Office and NERC, and which operates under civil aircraft rules, has already been identified for the demonstration/flight validation aspect of the proposed work. An existing measurement system we propose to base the new novel demonstrator on is already flying on this aircraft. We therefore propose to use the FAAM BAe 146 platform to flight validate the new measurement system to minimize costs. The existing system, a miniature non-flow invasive backscatter cloud spectrometer (BCP-100) was developed for the European Research Infrastructure Programme, IAGOS (In-Service Aircraft for Global Observing System), Figure 1. This has already received European Supplemental Type Certification (STC) approval for operation on Airbus A-320 series civil airliners as a component of the IAGOS instrument package programme and this will be expanded to other Airbus types, including A320/40, as IAGOS increases its fleet. The current Airbus platforms with their novel miniature IAGOS instrument packages will also offer a guaranteed future market base for the new system via upgrades and replacements, which will be managed by IAGOS and its extensive links with commercial carriers. Subsequent demonstration of the new system in this high profile environment for both airline safety and improved weather prediction and climate monitoring applications will be used to expand potential market for this system to other aircraft manufacturers with whom IAGOS is already in discussion.

Primary biological aerosols (PBA), or bioaerosols, are a poorly understood component of organic carbonaceous aerosols (OC), contributing a significant fraction to airborne particulate matter (PM) and comprising mixtures of many thousands of organic compounds. PBA include live or dead cells and cell fragments, fungal spores and pollens, and plant, insect and animal fragments. They have a major influence on the physico-chemical, biological, health and even climate related behaviour of atmospheric aerosols and chemical processes. The detection, characterization and classification of these aerosols and their descriptions in atmospheric transport models has remained a major challenge to the science community. Indeed the US national Academies of Science concluded that "The overall understanding of their impacts on atmospheric composition, climate, and human health remains weak." (NAS, 2016). Global and regional bioaerosol (PBA) emission and transport modelling studies have demonstrated very large uncertainties and thus provide limited understanding of these important atmospheric constituents. This is primarily due to a lack lack of observational data on their fluxes and airborne concentrations for many different ecosystems. Important, as yet unanswered, questions raised recently include: the relative importance of continuous versus intermittent emission and transport of PBA to ambient concentrations and subsequent impacts; whether PBA significantly influence cloud and precipitation processes via the "bioprecipitation" hypothesis; the degree to which they can reproduce via atmospheric ecosystem niches from the tropics to the poles; and whether they can influence chemical processes through degradation of organic compounds. All recent studies and reviews have similarly concluded that in order to start to address the many and growing challenges associated with PBA we need to acquire a better knowledge of their atmospheric concentrations and distributions and in particular knowledge of their vertical concentration profiles. The most recent in depth review of PBA, Fröhlich-Nowoisky et al. (2016), concluded that "major challenges include the quantitative characterization of exchange between surface, planetary boundary layer, and free troposphere. For this purpose, ground based measurements have to be combined with tall tower and aircraft measurements... to obtain information on the vertical and horizontal distribution of bioparticles." We aim to do just this, delivering new data sets to enable emissions modelling for the UK environment. We will use existing measurement facilities on the NERC FAAM aircraft together with surface measurements to deliver vertical and horizontal PBA concentration profiles over UK regions including urban, rural-cropland, grassland, forest & coastal. We will use aircraft bioaerosol sampling methodologies recently developed in the US together with real-time bioaerosol instruments. These data will provide the first such information on UK boundary layer concentration profiles of bioaerosol for over 50 years. High quality UK airborne data sets suitable for constraining & testing UK bio-emissions models for the first time. Our new vertically & horizontally resolved PBA-climate database will support a raft of scientific research and policy applications well beyond the timescale of the project. In situ PBA concentrations will be correlated with airborne meteorological, trace gas and other aerosol composition data, for air mass classification, using tools developed for the FAAM aircraft over many years for source tracking & identification. This will allow us to deliver quality controlled, assimilation-ready case studies able to constrain a wide range of potential PBA emissions models. We will also conduct laboratory experiments to deliver UK specific bioaerosol reference data sets designed to improve interpretation of current and future PBA field data collected using real-time UVLIF bioaerosol instruments.

The unique research capability of the Global Hawk, with ultra-long flights possible in the upper troposphere and lower stratosphere, provides a major new opportunity to advance atmospheric science. In response to the NERC/STFC/NASA collaborative initiative, we have assembled an experienced UK team that proposes to execute a research programme covering fundamental science and technology development, which, by working with the Global Hawk, will radically enhance our future research capabilities. The Tropical Tropopause Layer (TTL) is a crucial region for chemistry/climate interactions. Building on work we have already done in this area , we will collaborate with NASA's ATTREX programme to study the TTL over the Pacific Ocean and South East Asia, with new measurements and analysis. We will address fundamental questions related to atmospheric composition, radiation and transport. The TTL controls the transport of water vapour, the crucial radiative gas, into the stratosphere; we will advance understanding of the role of sub-visible cirrus in water vapour processes. The TTL is also the main route by which very short-lived halogen species, which represent a large uncertainty in future stratospheric ozone evolution, enter the stratosphere. We will improve knowledge of the budgets of these gases and of their chemical transformation and transport through the TTL, including the role of convective transport into the TTL and the subsequent routes for transport from the TTL to the lower stratosphere. Improving representation of these processes in global chemistry/climate models is a key aim. In order to study these processes, The FAAM BAe-146 will be deployed in Guam in Jan/Feb 2014. It will fly coordinated flights with the Global Hawk which will make measurements in the same period in the TTL over the West Pacific. Detailed involvement in all phases of the collaborative missions with ATTREX will enhance the UK potential for future research using the Global Hawk, including advanced capability in mission planning and methodologies for complex, real-time data analysis. The aircraft measurements will be interpreted in conjunction with ground-based and balloon-based measurements of very short-lived halogen species and ozone, using a complementary group of regional high resolution models, global composition models and a global cirrus model. We will develop and test two new instruments and new software for the payload/mission-scientist interface, which are ideally suited for the capabilities of the Global Hawk. One new instrument will allow quantification in the TTL of the important physical properties of sub- and super-micron sized particles, allowing new information about clouds and radiation. We will develop a new short-wave IR spectrometer to measure greenhouse (CO2, CH4, and H2O) and other (CO) gases in the lower atmosphere by remote sensing, taking advantage of the very long flights in the upper troposphere and lower stratosphere. Both instruments will be flight-tested in CAST. As well as addressing the specifics of this call, CAST addresses the central vision of the Technology theme: "to engage scientists, technologists, computer specialists and engineers working both within the NERC community and outside it, identifying that in many cases it will only be through developing new partnerships that the most challenging innovations in technology can be enabled" (http://www.nerc.ac.uk/research/themes/tap/documents/tap-technologies-2009.pdf). CAST brings new technology expertise in machine learning into the NERC community and strengthens the links between NERC scientists and the technology groups at Hertfordshire and the Astronomy Technology Centre.

Aerosol science, the study of airborne particles from the nanometre to the millimetre scale, has been increasingly in the public consciousness in recent years, particularly due to the role played by aerosols in the transmission of COVID-19. Vaccines and medications for treating lung and systemic diseases can be delivered by aerosol inhalation, and aerosols are widely used in agricultural and consumer products. Aerosols are a key mediator of poor air quality and respiratory and cardiac health outcomes. Improving human health depends on insights from aerosol science on emission sources and transport, supported by standardised metrology. Similar challenges exist for understanding climate, with aerosol radiative forcing remaining uncertain. Furthermore, aerosol routes to the engineering and manufacture of new materials can provide greener, more sustainable alternatives to conventional approaches and offer routes to new high-performance materials that can sequester carbon dioxide. The physical science underpinning the diverse areas in which aerosols play a role is rarely taught at undergraduate level and the training of postgraduate research students (PGRs) has been fragmentary. This is a consequence of the challenges of fostering the intellectual agility demanded of a multidisciplinary subject in the context of any single academic discipline. To begin to address these challenges, we established the EPSRC Centre for Doctoral Training in Aerosol Science in 2019 (CDT2019). CDT2019 has trained 92 PGRs with 40% undertaking industry co-funded research projects, leveraged £7.9M from partners and universities based on an EPSRC investment of £6.9M, and broadened access to our unique training environment to over 400 partner employees and aligned students. CDT2019 revealed strong industrial and governmental demand for researchers in aerosol science. Our vision for CDT2024 is to deliver a CDT that 'meets user needs' and expands the reach and impact of our training and research in the cross-cutting EPSRC theme of Physical and Mathematical Sciences, specifically in areas where aerosol science is key. The Centre brings together an academic team from the Universities of Bristol (the hub), Bath, Birmingham, Cambridge, Hertfordshire, Manchester, Surrey and Imperial College London spanning science, engineering, medical, and health faculties. We will assemble a multidisciplinary team of supervisors with expertise in chemistry, physics, chemical and mechanical engineering, life and medical sciences, and environmental sciences, providing the broad perspective necessary to equip PGRs to address the challenges in aerosol science that fall at the boundaries between these disciplines. To meet user needs, we will devise and adopt an innovative Open CDT model. We will build on our collaboration of institutions and 80 industrial, public and third sector partners, working with affiliated academics and learned societies to widen global access to our training and catalyse transformative research, establishing the CDT as the leading global centre for excellence in aerosol science. Broadly, we will: (1) Train over 90 PGRs in the physical science of aerosols equipping 5 cohorts of graduates with the professional agility to tackle the technical challenges our partners are addressing; (2) Provide opportunities for Continuing Professional Development for partner employees, including a PhD by work-based, part-time study; (3) Deliver research for end-users through partner-funded PhDs with collaborating academics, accelerating knowledge exchange through PGR placements in partner workplaces; (4) Support the growth of an international network of partners working in aerosol science through focus meetings, conferences and training. Partners and academics will work together to deliver training to our cohorts, including in the areas of responsible innovation, entrepreneurship, policy, regulation, environmental sustainability and equality, diversity and inclusion.

An aerosol consists of solid particles or liquid droplets dispersed in a gas phase with sizes spanning from clusters of molecules (nanometres) to rain droplets (millimetres). Aerosol science is a term used to describe our understanding of the collective underlying physical science governing the properties and transformation of aerosols in a broad range of contexts, extending from drug delivery to the lungs to disease transmission, combustion and energy generation, materials processing, environmental science, and the delivery of agricultural and consumer products. Despite the commonality in the physical science core to all of these sectors, doctoral training in aerosol science has been focussed in specific contexts such as inhalation, the environment and materials. Representatives from these diverse sectors have reported that over 90% of their organisations experience difficulty in recruiting to research and technical roles requiring core expertise in aerosol science. Many of these will act as CDT partners and have co-created this bid. We will establish a CDT in Aerosol Science that, for the first time on a global stage, will provide foundational and comprehensive training for doctoral scientists in the core physical science. Not only will this bring coherence to training in aerosol science in the UK, but it will catalyse new collaborations between researchers in different disciplines. Inverting the existing training paradigm will ensure that practitioners of the future have the technical agility and confidence to move between different application contexts, leading to exciting and innovative approaches to address the technological, societal and health challenges in aerosol science. We will assemble a multidisciplinary team of supervisors from the Universities of Bristol, Bath, Cambridge, Hertfordshire, Imperial, Leeds and Manchester, with expertise spanning chemistry, physics, biological sciences, chemical and mechanical engineering, life and medical sciences, pharmacy and pharmacology, and earth and environmental sciences. Such breadth is crucial to provide the broad perspective on aerosol science central to developing researchers able to address the challenges that fall at the boundaries between these disciplines. We will engage with partners from across the industrial, governmental and public sectors, and with the Aerosol Society of the UK and Ireland, to deliver a legacy of training packages and an online training portal for future practitioners. With partners, we have defined the key research competencies in aerosol science necessary for their employees. Partners will provide support through skills-training placements, co-sponsored studentships, and contribution to taught elements. 5 cohorts of 16 doctoral students will follow a period of intensive training in the core concepts of aerosol science with training placements in complementary application areas and with partners. In subsequent years we will continue to build the activity of the cohort through summer schools, workshops and conferences hosted by the Aerosol Society, virtual training and enhanced training activities, and student-led initiatives. The students will acquire a perspective of aerosol science that stretches beyond the artificial boundaries of traditional disciplines, seeing the commonalities in core physical science. A cohort-based approach will provide a national focal point for training, acting as a catalyst to assemble a multi-disciplinary team with the breadth of research activity to provide opportunities for students to undertake research in complementary areas of aerosol science, and a mechanism for delivering the broad academic ingredients necessary for core training in aerosol science. A network of highly-skilled doctoral practitioners in aerosol science will result, capable of addressing the biggest problems and ethical dilemmas of our age, such as healthy ageing, sustainable and safe consumer products, and climate geoengineering.