Arctic PRIZE will address the core objective of the Changing Arctic Ocean Program by seeking to understand and predict how change in sea ice and ocean properties will affect the large-scale ecosystem structure of the Arctic Ocean. We will investigate the seasonally and spatially varying relationship between sea ice, water column structure, light, nutrients and productivity and the roles they play in structuring energy transfer to pelagic zooplankton and benthic megafauna. We focus on the seasonal ice zone (SIZ) of the Barents Sea - a highly productive region that is undergoing considerable change in its sea ice distribution - and target the critically important but under-sampled seasonal transition from winter into the post-bloom summer period. Of critical importance is the need to develop the predictive tools necessary to assess how the Arctic ecosystems will respond to a reducing sea ice cover. This will be achieved through a combined experimental/modelling programme. The project is embedded within international Arctic networks based in Norway and Canada and coordinated with ongoing US projects in the Pacific Arctic. Through these international research networks our proposal will have a legacy of cooperation far beyond the lifetime of the funding. The project comprises five integrated work packages. WP1 Physical Parameters: We will measure properties of the water column (temperature, salinity, turbulent fluxes, light, fluorometry) in both open water and under sea ice by deploying animal-borne tags on seals which preferentially inhabit the marginal ice zone (MIZ). We will use ocean gliders to patrol the water around the MIZ and track it as the ice retreats northwards in summer. Measurements of underwater light fields will support development of improved regional remote sensing algorithms to extend the spatial and temporal context of the proposal beyond the immediate deployment period. WP2 Nutrient Dynamics: We will undertake an extensive program of measuring inorganic and organic nutrients, their concentrations, isotopic signatures and vertical fluxes to understand the role of vertical mixing and advection (WP1) in regulating nutrient supply to PP in the surface ocean. WP3 Phytoplankton Production: We will investigate nutrient supply (WP2) and light availability (WP1) linked to sea ice affect the magnitude, timing, and composition of phytoplankton production, and the role of seasonal physiological plasticity. Through new numerical parameterisations - cross-tuned and validated using a rich array of observations - we will develop predictive skill related to biological production and its fate; resolve longstanding questions about the competing effects of increased light and wind mixing associated with sea ice loss; and therefore contribute to the international effort to project the functioning of Pan-Arctic ecosystems. WP4 Zooplankton Behaviour: Zooplankton undergo vertical migrations to graze on PP at the surface. We will use acoustic instruments on moorings and AUVs, with nets and video profiles to measure the composition and behaviours of pelagic organisms in relation in light and mixing (WP1) and phytoplankton production (WP3) over the seasonal cycle of sea ice cover. The behaviours identified will be used to improve models that capture the life-history and behavioural traits of Arctic zooplankton. These models can then be used to investigate how feeding strategies of key Arctic zooplankton species may be modified during an era of reducing sea ice cover. WP5 Benthic Community: We will use an AUV equipped with camera system to acquire imagery of the large seabed-dwelling organisms to investigate how changes in sea ice duration (WP1), timing of PP (WP3) and bentho-pelagic coupling (WP4) can modify the spatial variation in benthic community composition. We will also conduct time series-studies in an Arctic fjord using a photolander system to record the seasonally varying community response to pulses of organic matter.

The balance between the production of organic carbon during phytoplankton photosynthesis and its consumption by bacterial, zooplankton and phytoplankton respiration determines how much carbon can be stored in the ocean and how much remains in the atmosphere as carbon dioxide. The amount of organic carbon stored in the ocean is as large as the amount of carbon dioxide in the atmosphere, and so is a key component in two global carbon cycle calculations needed to avoid a global temperature rise of more than 1.5 degrees C: the calculation of the technological and societal efforts required to achieve net zero carbon emissions and the calculation of the efficiency of ocean-based engineering approaches to directly remove carbon dioxide from the atmosphere. Yet, despite its vital role, our ability to predict how ocean carbon storage will change in the future is severely limited by our lack of understanding of how plankton respiration varies in time and space, how it is apportioned between bacteria and zooplankton and how sensitive it is to climate change-induced shifts in environmental conditions such as increasing temperature and decreasing oxygen. This woeful situation is due to the significant challenge of measuring respiration in the deep-sea and the uncoordinated way in which these respiration data are archived. This project will directly address these two problems. We will take advantage of our leadership and participation in an international programme which deploys thousands of oceanic floats measuring temperature, oxygen and organic carbon in the global ocean, in an international team of experts focused on quantifying deep-sea microbial respiration, and our experience of collating international datasets, to produce an unprecedented dataset of bacterial and zooplankton respiration. We will derive estimates of respiration based on data from floats, so that together with estimates derived from recently developed methods including underwater gliders, the new database will include respiration measurements calculated over a range of time and space scales. Crucially, respiration rates will be coupled with concurrent environmental data such as temperature, oxygen and organic carbon. This dataset will enable us to quantify the seasonal and spatial variability of respiration and derive equations describing how respiration changes with the proportion of bacteria and zooplankton present and with the chemical and physical properties of the water. These equations can then be used in climate models to better predict how respiration and therefore ocean carbon storage will change in the future with climate-change induced shifts in temperature, oxygen, organic carbon and plankton community. We will take part in a hybrid hands-on and online international training course on observations and models of deep-water respiration targeted to early career researchers from developing and developed countries to showcase the useability of the respiration database and the global array of oceanic floats. We will also prepare Science Festival exhibits on observing life in the deep ocean for schoolchildren. The deliverables of the project - a unique global open-access database of respiration measurements, new equations describing the sensitivity of respiration to changing temperature and oxygen suitable for climate models and online training materials for early career researchers - are of benefit to scientists who aim to predict how a changing climate will affect the storage of carbon in the ocean, educators who train the next generation of ocean scientists and practitioners, policy makers who need to quantify nationally determined contributions to actions limiting global warming, and scientists, engineers, lawyers, governing bodies and commercial companies designing, evaluating and implementing ocean-based carbon dioxide removal technologies.

Over periods of hundreds of millions of years, Earth's surface is recycled via the fragmentation of continents to form new oceans and elsewhere the sinking of oceanic plates into the mantle beneath. The breakup of continents involves progressive stretching and thinning prior to final breakup and the formation of new oceanic crust from molten rock that rises from below, flanked by continental margins comprised of thinned continental crust. There is a range of continental margin types, varying from those where the underlying mantle starts to melt very early in the process and very large volumes are added to the crust, to those "magma-poor" margins where there is little evidence for such melting until the very end of the process. At these magma-poor margins, which are common globally, it has been found that the crust can thin to nothing and mantle rocks can be exposed at the seabed, where they react with seawater in a process called serpentinisation. This serpentinisation plays an important role in exchange of chemicals between the Earth's interior and the ocean, and may be particularly intense around geological faults. While the final stages of thinning of the continental crust have been studied extensively over the past three decades, the transition from exposing mantle at the seabed through to forming new oceanic crust by the eruption of molten rock has been less well studied. Even designing such a study can be challenging because it is often unclear how wide this transition is. Also, because such mantle exposure has also been found in the middle of the oceans, this transition may be more complicated than often assumed. Our project will use a novel combination of geophysical techniques to study this final stage of continental breakup at a magma-poor continental margin southwest of the UK. There, crust that seems from all available data to be "normal" oceanic crust lies within about 150 km of crust confirmed by drilling to be continental. A region of serpentinised mantle, now overlain by up to around 1 km of mud, lies in between. For the first time in such a location, we will use electromagnetic waves, generated from a towed source, to measure the electrical resistivity of the crust and serpentinised mantle. Electromagnetic waves are strongly attenuated by seawater, so the source must be powerful and must be towed close to the seabed. We will use a combination of towed sensors, that are most sensitive to structures just below the seabed, and seabed detectors that can measure tiny fluctuations in electrical and magnetic fields at distances of up to tens of kilometres from our source, and thus allow us to probe deeper. We will also use some of the same seabed receivers to detect sound waves travelling through the crust from a source towed close to the ship, and to detect lower-frequency electromagnetic waves that are generated by natural sources and penetrate deeper into the Earth. The data that we collect will allow us, via the use of powerful computer programmes, to construct models of the variation of both sound speed and electrical resistivity in the crust and in the upper few tens of kilometres of the mantle beneath. These parameters provide a powerful combination because they are sensitive in different ways to the nature of the rocks. The electrical resistivity is particularly sensitive to the presence of water, and also of a mineral called magnetite that can be formed during the process of serpentinisation. The sound velocity is less sensitive to the presence of water but can be more sensitive to variations in the minerals present. From our models, we expect to be able to distinguish the continental crust and mantle, the oceanic crust and mantle, and the nature of the materials in between. We will then link these observations to computer models of the physical and chemical processes occurring as continents break apart. Thus we will find out how the formation of new oceanic crust actually starts.

The National Oceanography Centre (NOC) operates ocean gliders for the Met Office and Royal Navy to collect earth observations, driving ocean forecast models. These models, in turn, underpin operational weather forecasts. Currently, observations are targeted at ocean model grid boxes in high-impact areas of UK waters. An extension of this approach is to optimise ocean glider observations to maximise their impact on ocean models and, thus, weather forecasts using the concept of an interoperable Digital Twin (DT) building on recent IMFe recommendations. We propose a demonstrator digital twin which combines earth observations with sub-surface ocean glider data and operational ocean model. The resulting novel four-dimensional picture will be presented through a User interface (UI), allowing scientists to identify the potential observations which could have the most impact, and allowing the definition of operational objectives to be achieved those observations. The objectives will feed a mission planning service that will take account of glider capabilities (such as battery life and speed) to re-task the glider, thus optimising the observations for most impact, creating a virtuous feedback circle between the observing capability and the ocean model data assimilation. This feedback between scientists, earth observation data, and glider operations in near real-time will maximise the value of the observations collected and their impact on ocean forecasting. This in turn will maximise the societal value of these publicly funded ocean observations. While this project will assemble and demonstrate the digital twin around Met Office operations, this DT will be a generic framework that will support plug-and-play interoperability of different models and autonomy engines to drive observations to optimise models. It is envisaged the applicability of the results will scale to the piloting operations for marine autonomous systems spanning a wide range of vehicle operations including the NERC research community. The work will build on, and directly contribute to further development of the Information Management Framework for environmental digital twins (IMFe), focusing on the interfaces between existing components via a communities of practice approach with best practices being included in community outputs (such as the Turing way and the TWINE community). This will enable the reuse of project outputs by the broader digital twin community. The project also aims to sustain the NERC Digital Twins senior stakeholder forum under the umbrella of the TWINE grouping of projects.

The ocean is a large carbon reservoir which contains fifty times the amount of carbon in the atmosphere. Biological processes contribute to carbon storage in the ocean on climate-relevant timescales (hundreds to thousands of years). Marine phytoplankton, which are drifting microscopic plants, use sunlight and carbon dioxide in the upper ocean to form their biomass, also called organic matter. When phytoplankton die they sink into the ocean interior, moving organic carbon deeper in the water column; the deeper it goes the longer it will remain out of contact with the atmosphere. This process, often called the biological carbon pump, helps to regulate our climate and without biology in the ocean it has been shown that atmospheric carbon dioxide levels could be nearly double what they are today. In this project we will examine three ways in which biological processes influence global ocean carbon storage, and where knowledge gaps are hindering progress on predicting ocean carbon storage in the future. First, is understanding how the buffering capacity of seawater changes, driven by phytoplankton that produce chalk shells, which ultimately affects CO2 uptake. Second, is understanding the efficiency and variability of the primary production of organic matter by phytoplankton. Third, is understanding how much of this organic matter reaches the interior ocean, which tells us how much carbon has been respired during the transit from the upper ocean. Earth system models have differing simplistic representations of the biological carbon pump due to the computational costs of running global models far into the future. The suite of models that contribute to the Intergovernmental Panel on Climate Change (IPCC) reports do not agree on the magnitude or direction of change for ocean carbon storage under future climate scenarios. This means we have low confidence for our future projections, which is further impeded by a growing discrepancy between models and observations. This project will identify the gaps in our understanding and highlight model limitations for each of the three areas outlined above. We will achieve this by reviewing the current literature to identify key processes. We will assess the differences in how current climate models represent changes in the buffering capacity, primary production of organic matter and the amount of interior respiration, and how these differences may affect future ocean carbon storage projections. This will aid in identifying the observations that are needed to improve our grasp of the processes controlling the biological carbon pump, which will in turn allow for improved model representations and predictions. We aim to identify the priority processes that are significant contributors to biological carbon storage, have the potential to be widely measured to allow robust model representations, can be feasibly included into models, and are relevant over long timescales and globally. We will carry out an expert assessment by asking the international scientific community to rank which processes are the most significant for ocean carbon storage and climate feedbacks. Our analysis and the survey results will inform recommendations for future field programmes based on the tractability of observing key processes, and the likelihood of being able to include them in models.