In response to climate change many temperate glaciers worldwide, including Skeidararjokull in SE Iceland, are retreating. Associated with this retreat is the appearance and expansion of proglacial lakes. These proglacial lakes lead to the outwash plains (sandar) being disconnected or decoupled from the glacier. Consequently, the sediment that would otherwise be deposited on the sandar is instead trapped within these lakes, leading to sediment deprivation of the distal sandar which in-turn impacts the fluvial and coastal systems. The recent formation of proglacial lakes also provides new challenges jokulhlaup hazard assessment. Despite their importance, there have been no detailed studies of large-scale proglacial sedimentary systems undergoing active decoupling, and the role of this process for sediment flux and landscape development remains unclear. In December 2021 Grimsvotn subglacial lake drain 0.9 km3 of water as a jokulhlaup from Skeidararjokull. This provides a rare opportunity to capture the geomorphological and sedimentary signature of a jokulhlaup within a subaqueous setting and assess the role that proglacial lakes have in altering the response of the downstream fluvial and coastal system. The overall aim of the project is to improve understanding of the impact of jokulhlaups on landform and sedimentary assemblages within proglacial lakes and assess the impact of these lakes on the glacifluvial and coastal system of Skeidararsandur. SE Iceland. The collection and analysis of data from the 2021 December jokulhlaup will enable accurate prediction and modeling of the impacts of larger future events that will assist our project partners, the Icelandic Meteorological Office, to provide better early warning of floods.

Lava flows from eruptions on Reykjanes peninsula in Iceland started burning urban structures on 14 January 2024. Volcanic emissions and urban fires, respectively, are known to contain many chemical compounds that are hazardous to health. While these distinct end member compositions are better known, lava-urban interface (LUI) emissions have not been studied. Key hypotheses: LUI emissions have unique chemistry due to the combination of volcanic and human-made compounds. The interaction impacts the combustion process, the composition of the emissions released into the environment, and the chemical reaction pathways in the atmospheric plume. The LUI interaction may also be modifying the degassing processes in the lava, and release of magmatic volatiles. Eruptions at the urban interface lead to higher human exposures than remote eruptions because of their proximity to communities; and small eruptions can cause severe air pollution in populated areas. Lava encounters urban space quasi-periodically, for example Kilauea, Hawaii 2018, Cumbre Vieja, La Palma 2021 and now on Reykjanes, Iceland (2024 - present). Despite the recognition of the importance of characterising chemistry of air pollution sources, LUI emissions remain unstudied, likely due to a combination of challenging sampling conditions, and the unpredictability and the short duration of each eruptive episode. Globally, the number of people exposed to LUI emissions is growing because of building expansion into previously uninhabited areas. For instance, the homes burned by lava in Iceland in January 2024 were newbuilds, the construction of which began when the volcanic system was already in unrest. We will use the ongoing activity in Iceland as a natural laboratory for the first ever characterisation of LUI emission chemistry at-source and in the near-field (1-40 km distance).

Eyjafjallajokull, a 1666 m high, glacier-clad, stratovolcano in southern Iceland, is known to have erupted on four previous occasions in the historic record: ~500 AD, ~920 AD, 1612 AD and 1821-23 AD. Each eruption has resulted in rapid and large-scale glacier ice melt, generating very large jokulhlaups (glacier outburst floods) with peak discharges of 10^3-10^4 m^3s^-1 inundating the surrounding populated lowlands. On March 3rd 2010, the Icelandic Meteorological Office (IMO) informed us of a period of enhanced seismic activity under Eyjafjallajokull (since the beginning of January 2010). Based on the assumption that the exponential increase in both seismic activity and rates of ground deformation represented pre-eruption behaviour and intrusion of a magma tongue into the Earth's crust at this location, we collected pre-eruption Terrestrial Laser Scanner and dGPS survey data from a number of probable jökulhlaup routeways between March 9th and 16th 2010. Five days after the end of this data acquisition period (on March 20th 2010), the magma reached the surface along a newly formed 500 m-long fissure located north of Fimmvorduháls pass and directly east of the Eyjafjallajokull ice cap. This phase of eruption was on a non-ice covered area and activity ceased on April 12th. Only two days later (April 14th at 02:00 GMT) a large subglacial explosive eruption started beneath the 2.5 km-wide summit caldera of Eyjafjallajokull (to the west of the original fissure eruption). Within hours the eruption melted through 200 m of the ice cap and became fully phreatic, producing a major 8.5 km-high volcanic plume (with subsequent serious implications for pan-European air traffic). By 07:00 GMT on April 14th, rapid melting of the Eyjafjallajokull ice cap generated volcanogenic jokulhlaups that cascaded from Gigjokull and down Nupakotsdalur on the northern and southern flanks of Eyjafjallajokull respectively. The initial jokulhlaup from Gigjokull reached peak discharge in the Markarfljot river system several hours later, damaging Iceland's main ring road near the Markarfljot bridge. Subsequent increases in eruption intensity generated repeated jokulhlaups from Gigjokull that inundated the Markarfljot. On an overflight at 18:55 GMT on April 15th, Dr Matthew Roberts (Icelandic Met Office & project partner) witnessed an enormous jokulhlaup (peak discharge ~ 10^4 m^3s^-1) from Gigjokull which prompted the immediate evacuation of the population within the entire Markarfljot area. This jokulhlaup was 'sediment-laden', characterised by a viscous, smooth-surfaced, lobate flow front followed by a more turbulent fluid flow body. These initial observations suggest that the frontal wave of this jokulhlaup was hyperconcentrated. In this project, we aim to improve understanding of volcanogenic jokulhlaup impacts and processes due to a subglacial volcanic eruption. In order to do this, we will acquire post-jokulhlaup data for the Gigjokull proglacial area and the Markarfljót to compare against our directly pre-eruption (9th -16th March 2010), full 3D TLS topographic datasets. We therefore have an UNPRECEDENTED and UNIQUE OPPORTUNITY to (1) accurately quantify the geomorphological and sedimentary characteristics of a series of jokulhlaups and (2) to use these to inform and validate our reconstructions of the hydrodynamic characteristics of a series of volcanogenic jokulhlaups capable of valley-scale geomorphological and sedimentary impact. To do this, we need to re-survey areas for which we have important baseline data but where the evidence of volcanogenic jokulhlaup impacts and processes is transient (hence this Urgency application to NERC). A second and important phase of the project will use this data to model the impacts of the eruption on the outflow system.

Since the eighteenth century, weather balloons have been used as a carrier platform to make observations of the weather in our atmosphere. Fundamental discoveries about the structure of the atmosphere were made by early investigators. Atmospheric processes such as the electrification in thunderstorms and the thickness of the ozone layer have been observed using balloon-borne instrumentation. On a daily basis, hundreds of weather balloons are launched by meteorological organizations across the world to observe the state of the atmosphere, providing the initial conditions for weather forecasts. Weather balloons are also used during field campaigns as an essential tool for studying the atmosphere. A modern weather balloon system consists of a balloon supporting a radiosonde. The radiosonde is a small device which contains a radio transmitter, weather sensors, GPS and batteries. Its radio link relays weather data to a ground station, making the device disposable. Radiosondes are rarely used for anything more than standard weather measurements. Other than a small percentage used to routinely measure the thickness of the ozone layer, weather balloon are an under-exploited measurement platform in the scientific community. Weather balloons that have the potential to carry ozone sensors have an interface to send additional information via the radiosonde for relay to the ground station. For little extra cost it is possible to add other sensors to this interface. In the Department of Meteorology at the University of Reading, a simplified data connection system has been developed allowing multiple sensors to be interfaced and powered with the radiosonde. The additional data is relayed over the existing radio link, hence no additional receiving hardware is required. Software installed at the ground station combines the standard weather data with the additional sensor data. Small disposable sensors have been developed to measure turbulence, solar radiation, optical properties of clouds, and high-energy particle concentration. The automated disposable nature of the radiosonde allows additional measurements to be made with minimal cost when compared to that of a research aircraft. During hazardous conditions for aircraft, weather balloons provide a low-risk method to obtain measurements, which was demonstrated by the proposers during the 2010 and 2011 Icelandic volcano eruptions. This project proposes to develop a multi-sensor miniature laboratory to sample hazardous volcanic plumes. The package of five bespoke sensors will measure ash, SO2, ice, electrification, and turbulent mixing. The sensor package will be carried by weather balloons and aims to improve the quality of decision-making and the predictive skill of forecast models, when a volcanic ash cloud next threatens international airspace.

The ongoing eruption at Fagradalsfjall in Iceland presents an outstanding and rare opportunity to observe and model the behaviour of dense volcanic gases. Sulphur Dioxide (SO2) is the principal emission from lava-rich eruptions such as at Fagradalsfjall. With more than double the molecular weight of air, this is prone to exhibiting dense gas dispersion characteristics such as settling, with the potential to significantly affect the dispersion over scales of hundreds of kilometers. This can lead to enhanced concentrations at low levels with consequences for air quality and human health. This project aims to (a) collect a surface air quality and meteorological dataset and (b) produce a modelling framework capable of simulating dense gas and validate it against (a). Such a framework does not exist at present. This is a significant, time-limited and accessible eruption event which, if responded to now, can lead to major advances in both scientific understandings and in the management of future, possibly larger, eruptions from which there is a serious gas hazard. (A) We will enhance existing air quality observations in the vicinity of Fagradalsfjall, creating a network to provide a comprehensive assessment of dense volcanic gas dispersion on a scale of 50-100 km. This unique dataset will provide the first independent verification for a full meteorological prediction model with dense gas capability coupled with surface heating (see below). (B) Recent model development work has demonstrated effective volcanic gas dispersion predictions using an adapted version of the NCAR Weather Research and Forecasting (WRF) model. This system was used to successfully interpret aircraft measurements of CO2 dispersion from the (subglacial) Katla volcano in Iceland and to explain quantitatively, for the first time, the dense gas CO2 behaviour which led to the Lake Nyos disaster in 1986 that saw dense CO2 pooling and draining down valleys, causing ~1700 deaths. Neither of these applications considered (or required) a heated surface. However, the Fagradalsfjall eruption is now in a phase where lava fountains have been reported, and so the effect of surface heating will need to be considered in any modelling, to include the complex interactions and feedbacks between a dense gas, a heated surface, and the underlying meteorology. The model, after development and verification, will be available in the future as an operational hazard prediction system and and could lead to significant improvements in the UK national capability to respond to dense gas releases. This includes anthropogenic releases, for example industrial accidents and fires.