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Publisher's version (útgefin grein) ; Volcanic ash in the atmosphere is a hazard to aviation. To predict which areas of airspace are most likely to be affected by the presence of ash, Volcanic Ash Advisory Centers (VAACs) use observations and atmospheric dispersion models. These models are initialized with, among other parameters, a mass eruption rate (MER), which quantifies the emission rate into the atmosphere at the source. This influences the predicted spatial–temporal evolution and concentration of the ash cloud. Different models are available to estimate MER from the volcanic plume height and some models also include the weather conditions (e.g., wind speed). The REFIR software tool uses time-series of plume height estimated from observations and weather data to provide estimates of MER through time. Here we present an updated version of REFIR that can now be used also to calculate MER for past eruptions and produce output parameters in a format suitable for use with the NAME dispersion model (UK Met Office—London VAAC). We also investigate how uncertainty in input parameters is propagated through to dispersion model output. Our results show that a +/−1 km uncertainty on a 6 km high plume can result in the affected area ranging by a factor of three between the minimum and maximum estimates. Additionally, we show that using wind-affected plume models results in affected areas that are five times larger than using no-wind-affected models. This demonstrates the sensitivity of MER to the type of plume model chosen (no-wind- vs. wind-affected). ; We thank Larry Mastin, Arnau Folch, and an anonymous reviewer for their comments and suggestions that contributed to the improvement of the manuscript, and Lynn Russell for the editorial handling. We also thank Dr. Susan Loughlin (British Geological Survey), Dr. Susan Leadbetter (UK Met Office) and Dr. Claire Witham (UK Met Office) for their valuable suggestions. Fabio Dioguardi and John A. Stevenson have been supported from UK National Capability funding (BGS Innovation Flexible Fund). Fabio Dioguardi has also been supported by the European Union's Horizon 2020 project EUROVOLC (grant agreement no 731070). Tobias D?rig's work is supported by the Icelandic Research Fund (Rann?s) grant no. 206527-051. This work is published with permission of the Executive Director of British Geological Survey (UKRI) ; Peer Reviewed

Publisher's version (útgefin grein) ; Meaningful forecasting of the atmospheric concentration and ground accumulation of volcanic ash during explo-sive eruptions requires detailed knowledge of the eruption source parameters. However, due to the large uncer-tainties in observations and limitations of current models used to make inferences from these, monitoring anongoing eruption and quantifying the mass eruption rate in real-time is a considerable challenge. Within theEU supersite project"FutureVolc", an integrated approach has been applied to develop a quasi-autonomousmulti-parameter system, denoted"REFIR", for monitoring volcanic eruptions in Iceland and assessing the erup-tion massflow rate by inverting the plume height information and taking account of these uncertainties. REFIRhas the capability to ingest and process streaming plume-height data provided by a multitude of ground basedsensors, including C–and X-band radars and web-cam based plume height tracking systems. These observationaldata are used with a suite of plume models that also consider the current wind and other atmospheric conditions,providing statistically assessed best estimates of plume height and mass eruption rate. Provided instrumentaldata is available, near real-time estimates are obtained (the delay corresponding to the scan rate of data-providing instruments, presently of the order of minutes). Using the Hekla 2000, and Eyjafjallajökull 2010 erup-tions in Iceland, the potential of REFIR is demonstrated and discussed through application to three scenarios. Thesystem has been developed to provide maximumflexibility. A setup script assists the user in adapting to localconditions, allowing implementation of REFIR for any volcanic eruption site worldwide. REFIR is designed to beeasily upgradable, allowing future extension of monitoring networks, learning from new events, and incorpora-tion of new technologies and model improvements. This article gives an overview of the basic structure, modelsimplemented, functionalities and the computational techniques of REFIR. ; The development of REFIR has been part of the FUTUREVOLC supersite project and was funded by the European Union's Seventh Programme for research, technological development and demonstration under grant agreement No 308377. TD's work was also funded by the project EVER-EST, as part of the EU's Horizon 2020 research and innovation programme under grant agreement no 674907. ; Peer Reviewed

The effusive six months long 2014-2015 Bárðarbunga eruption (31 August-27 February) was the largest in Iceland for more than 200 years, producing 1.6 ± 0.3 km3 of lava. The total SO2 emission was 11 ± 5 Mt, more than the amount emitted from Europe in 2011. The ground level concentration of SO2 exceeded the 350 µg m−3 hourly average health limit over much of Iceland for days to weeks. Anomalously high SO2 concentrations were also measured at several locations in Europe in September. The lowest pH of fresh snowmelt at the eruption site was 3.3, and 3.2 in precipitation 105 km away from the source. Elevated dissolved H2SO4, HCl, HF, and metal concentrations were measured in snow and precipitation. Environmental pressures from the eruption and impacts on populated areas were reduced by its remoteness, timing, and the weather. The anticipated primary environmental pressure is on the surface waters, soils, and vegetation of Iceland. ; Funding for the research came from the Icelandic government via the Icelandic Civil Protection Agency, the EC FP7 Framework programme via the Futurevolc project, the Swedish Research Council FORMAS supported the DOAS measurements Geochemical Perspectives Letters Letter Letter Geochemical Perspectives Letters 92 Geochem. Persp. Let. (2015) 1, 84-93 | doi:10.7185/geochemlet.1509 Geochem. Persp. Let. (2015) 1, 84-93 | doi:10.7185/geochemlet.1509 93 and The French centre of excellence "Clervolc" programme financed the microprobe analysis. We are grateful to the Environmental Protection Agency in Ireland, the National Institute for Public Health and the Environment in the Netherlands, the Belgian Interregional Environment Agency, the Department for Environment Food & Rural Affairs in UK, and the Environment Agency of Austria for ground–level SO2 concentration data in air in the respective countries. ; Peer Reviewed