The Tropical South Pacific (TSP) is a vast area of ocean containing over 5000 small islands supporting a vulnerable human population of c.10 million of which 57% live within 1 km of the coast. All life on these islands depends on reliable precipitation for the provision of freshwater and food security, meaning that changes in the location and intensity of rainfall can result in damaging and costly societal impacts via droughts and flooding, with historical evidence of island abandonment and population migration. Within the TSP, over 10 million people and sensitive ecosystems on the 5700 isolated Pacific islands depend on rainfall from the convective processes generated in the South Pacific Convergence Zone (SPCZ), which is the largest convergence zone in the Southern Hemisphere, and influences regional, hemispheric and global climate, and in turn is influenced by ENSO and other remote modes of climate variability. Movement and strength of SPCZ convergence results in seasonal, interannual and longer term change in precipitation which are linked to severe droughts, cyclone paths resulting in impacts on Pacific island nations ability to meet Sustainable Development Goals, and in the past drove periods of mass human migration. In the last 1000 years, sustained periods of lower rainfall are thought to have contributed to the abandonment of some Atoll islands and the decision to migrate east into the Pacific. In other islands, changes in rainfall led to the development of different styles of agricultural system. However, compared to other parts of the earth, there is comparatively limited information about past precipitation changes in the TSP, in part because of a historical lack of suitable proxies and archives for producing high resolution, continuous records. Proxies for precipitation reconstructed from sediments or stalagmites are limited to marginal areas to the SPCZ and are also short (<600yrs) or have gaps in the timeseries. Current evidence indicates that decadal-centennial changes in SPCZ/TSP precipitation are linked to global modes of remote climate variability, particularly in the Atlantic, the rest of the Pacific, and the Southern Ocean, but our data to test theories or to validate GCMs is relatively short (<100 years). To address the lack of data and to create a step change in our understanding of the processes by which change is generated in the SPCZ by external modes of climate variability we will generate new network of high resolution (10-50yr) quantitative precipitation records from the whole SPCZ region that will capture its movement and change in strength over a 3500 period when we know large changes have occurred. We will utilise new multiproxy syntheses of palaeoclimate records alongside reconstructions of candidate modes of variability such as the Interdecadal Pacific Oscillation (IPO) and Atlantic Multidecadal Variability (AMV) and Southern jet stream index (SAM) to test for their relationship to SPCZ rainfall. Using a global climate/circulation model we will run a suite of experiments using plausible scenarios of modes of climate variability, either in isolation, or combined with each other, and informed by existing and new proxy data. These experiments will allow us to understand the processes by which different modes of climate variability drive SPCZ rainfall, and thus create fundamental new understanding of the decadal-scale SPCZ changes likely under different past and future modes of climate variability. We can achieve this research now due to the timely collaboration between the team currently leading quantitative hydroclimate reconstruction in the SPCZ and Tropical South Pacific (Sear, Sachs, Langdon, Ladd, Croudace), and the team currently leading the mechanistic understanding and modelling of the SPCZ over a range of time scales (seasonal - multidecadal) (Joshi, Matthews, Roberts, Brown, Osborn).

We propose a network to stimulate new international collaboration in measuring and understanding the surface temperatures of Earth. This will involve experts specialising in different types of measurement of surface temperature, who do not usually meet. Our motivation is the need for better understanding of in situ measurements and satellite observations to quantify surface temperature as it changes from day to day, month to month. Knowing about surface temperature variations matters because these affect ecosystems and human life, and the interactions of the surface and the atmosphere. Surface temperature (ST) is also the main indicator of "global warming". Knowledge of ST for >150 years has been derived from in situ meteorological and oceanographic measurements. These have been fundamental to weather forecasting, to environmental sciences, and to detection and attribution of climate change. Thermal remote sensing of ST from space has a ~30 year history, including operational exploitation. Observations of high accuracy and stability come from the 20-year record of Along Track Scanning Radiometers (ATSRs) . ATSR-class capability will shortly become operational in the space segment of Global Monitoring for Environment and Security (GMES), and will continue until at least 2030. The best insight into ST variability and change through the 21st century will come from jointly using in situ and multi-platform satellite observations. There is a clear need and appetite to improve the interaction of scientists across the in-situ/satellite 'divide' and across all domains of Earth's surface. This will accelerate progress in improving the quality of individual observations and the mutual exploitation of different observing systems over a range of applications. Now is a critical time to initiate this research network. First, the network will link closely to a major new initiative to improve quantification of ST from surface meteorological stations (surfacetemperatures.org). Second, there are areas of acute need to improve understanding of ST: e.g., across regions of Africa, where in situ measurements are very sparse; and across the Arctic, where the evolving seasonal sea ice extent challenges the current practices for quantifying ST variability and change. Third, it is timely to share experience between remote sensing communities. All these motivations are present against a backdrop where ST is, in relation to climate change, of current public interest & relevance to policy. This network will increase the international impact of UK science. UK investigators are involved across the full scope of the proposed ST network, and have leading international roles in several areas. The network will ensure UK participation at the highest level across all domains of ST research. In this proposal, key world-class organisations overseas have roles in steering and/or hosting network activities. The network will welcome participation of others not contacted in preparation of this proposal. Permission will be sought from the originators of all data used for case studies to make the data set freely available. The network will be organised around three themes over three years: Year 1. In situ and satellite ST observations: challenges across Earth's domains Year 2: Quantifying surface temperature across Arctic Year 3: Joint exploitation of in situ and satellite surface temperatures in key land regions. The first theme is an inclusive question, designed to bring together research communities and develop a full picture of common research needs and aspirations. The second theme is a pressing research question to which the network will co-ordinate a useful and unique contribution. The third theme is one of long-term interest and importance in the strengthening of the observational foundations for climate change monitoring and diagnosis.

We propose a network to stimulate new international collaboration in measuring and understanding the surface temperatures of Earth. This will involve experts specialising in different types of measurement of surface temperature, who do not usually meet. Our motivation is the need for better understanding of in situ measurements and satellite observations to quantify surface temperature as it changes from day to day, month to month. Knowing about surface temperature variations matters because these affect ecosystems and human life, and the interactions of the surface and the atmosphere. Surface temperature (ST) is also the main indicator of "global warming". Knowledge of ST for >150 years has been derived from in situ meteorological and oceanographic measurements. These have been fundamental to weather forecasting, to environmental sciences, and to detection and attribution of climate change. Thermal remote sensing of ST from space has a ~30 year history, including operational exploitation. Observations of high accuracy and stability come from the 20-year record of Along Track Scanning Radiometers (ATSRs) . ATSR-class capability will shortly become operational in the space segment of Global Monitoring for Environment and Security (GMES), and will continue until at least 2030. The best insight into ST variability and change through the 21st century will come from jointly using in situ and multi-platform satellite observations. There is a clear need and appetite to improve the interaction of scientists across the in-situ/satellite 'divide' and across all domains of Earth's surface. This will accelerate progress in improving the quality of individual observations and the mutual exploitation of different observing systems over a range of applications. Now is a critical time to initiate this research network. First, the network will link closely to a major new initiative to improve quantification of ST from surface meteorological stations (surfacetemperatures.org). Second, there are areas of acute need to improve understanding of ST: e.g., across regions of Africa, where in situ measurements are very sparse; and across the Arctic, where the evolving seasonal sea ice extent challenges the current practices for quantifying ST variability and change. Third, it is timely to share experience between remote sensing communities. All these motivations are present against a backdrop where ST is, in relation to climate change, of current public interest & relevance to policy. This network will increase the international impact of UK science. UK investigators are involved across the full scope of the proposed ST network, and have leading international roles in several areas. The network will ensure UK participation at the highest level across all domains of ST research. In this proposal, key world-class organisations overseas have roles in steering and/or hosting network activities. The network will welcome participation of others not contacted in preparation of this proposal. Permission will be sought from the originators of all data used for case studies to make the data set freely available. The network will be organised around three themes over three years: Year 1. In situ and satellite ST observations: challenges across Earth's domains Year 2: Quantifying surface temperature across Arctic Year 3: Joint exploitation of in situ and satellite surface temperatures in key land regions. The first theme is an inclusive question, designed to bring together research communities and develop a full picture of common research needs and aspirations. The second theme is a pressing research question to which the network will co-ordinate a useful and unique contribution. The third theme is one of long-term interest and importance in the strengthening of the observational foundations for climate change monitoring and diagnosis.

Beijing suffers from very high concentrations of airborne pollutants, leading to adverse health and wellbeing for over twenty million people. The pollutants likely to have the greatest effects upon human health are particulate matter, nitrogen dioxide and ozone. Both particulate matter and nitrogen dioxide are emitted directly from individual sources (primary contributions, many of which are not well quantified); and are formed in the atmosphere (secondary contributions, which are highly complex). Ozone is entirely secondary in nature, formed from reactions of precursor gases, whose sources and abundance are also challenging to constrain. These uncertainties hinder understanding of the causes of air pollution in Beijing, which is needed to deliver effective and efficient strategies for pollution reduction and health improvement. AIRPOLL-Beijing project will address this challenge, through identification and quantification of the sources and emissions of air pollutants in Beijing. The project sits within the NERC/MRC-NSFC China megacity programme, which includes projects addressing the atmospheric processes affecting air pollutants, human exposure and health effects, and solutions / mitigation strategies to reduce air pollution and health impacts. The project exploits the combined experience and expertise of leading UK and Chinese scientists, applying multiple complementary approaches. The project deploys multiple atmospheric measurement and analysis strategies to characterise pollutant abundance and sources, develop novel emissions inventories, and integrate these to produce new modelling tools for use in policy development. We adopt a range of state-of-the-science approaches: -Receptor Modelling, where detailed composition measurements are used to infer pollutant sources from their chemical signatures, combining world-leading UK and Chinese capability. -Flux Measurements, where the total release of pollutants from all sources is measured, providing a key metric to refine emission inventories. We will combine near-ground measurements (using the unique Institute of Atmospheric Physics 325m tower in central Beijing), ground-based observations and fluxes derived from satellite observations. -3D spatial analysis, in which a novel sensor network will be deployed around central Beijing to measure pollutant fields. -Development of novel emissions inventories, which will predict the temporally- and spatially- resolved emissions of air pollutants from all sources, enhancing existing capability. -Development of new online modelling tools, within which to integrate emissions, atmospheric processing and meteorology to predict primary and secondary pollutant concentration fields. AIRPOLL-Beijing will integrate these approaches to provide thorough understanding of the sources and emissions of air pollutants in Beijing, at unprecedented detail and accuracy. While the project is a self-contained activity, key deliverables feed into Processes, Health and Solutions themes of the programme. This proposal seeks Newton fund support, part of the UK's Official Development Assistance (ODA) commitment. The project will directly address ODA objectives, in the categories of (i) people (through the joint development of novel scientific approaches to the understanding of megacity air pollution), (ii) programmes (as all aspects of the project are joint UK-Chinese research endeavours) and (iii) translation (through provision of detailed air pollution source assessments, in support of assessment of health impacts and development of mitigation strategies). More generally, the project will leave a legacy of improved air pollution understanding and research capacity of the Chinese teams, and, through integration with other themes of the Megacities programme, underpin improvements in the health and welfare of the population of Beijing, and across China more widely - ultimately benefitting more than a billion people.