Radar-supported Next-Generation Forecasting of Volcanic Ash Hazard (R4AsH)

Volcanic plumes from explosive eruptions present a global hazard to health, the environment and the economy. The disruption caused by airborne ash to aviation is well documented and can have serious financial repercussions. Consequently, forecasting the extent and evolution of ash-rich plumes is vital for hazard assessment. However, the accuracy of numerical plume models is currently limited by uncertainties in the input eruption parameters, or 'source term', that describe the initial distribution of ash in the atmosphere.

We will develop a new approach to improve estimates of source term parameters by combining advanced numerical models, techniques for understanding uncertainty and state-of-the-art satellite observations of volcanic plumes. Applying this method to data from recent eruptions will provide critical insight into how plumes evolve as they are dispersed, and into the processes involved, such as particle sedimentation and aggregation. We currently have no technique for observing these processes in the critical source term region, and such real-time data would be transformational for ash hazard forecasting. To address this, we propose multi-frequency radar as a powerful new measurement tool capable of providing the key source term parameters that describe particle size distribution and mass loading. We will develop and demonstrate the potential of this technique using laboratory experiments and advanced numerical simulations of plumes. The results will be immediately relevant to existing single-frequency radar systems currently used to observe plumes, and will inform the design and deployment of next-generation multi-frequency systems.

This project is a collaboration between volcanologists, atmospheric and radar physicists and meteorologists, who are expert in laboratory experiments, remote sensing, uncertainty in environmental systems and numerical modelling. By working directly with the UK Met Office, we will deliver a new level of uncertainty understanding into operational long-range airborne ash concentration forecasts. The results will be of enormous benefit to international workers in volcanic plume forecasting and hazard assessment, and will open the door to near-real-time 3D quantification of plume processes. More accurate forecasts of the dispersal of ash in the atmosphere will enable improved mitigation for health effects, infrastructure damage, agricultural contamination and aviation hazards to deliver significant and globally relevant social, environmental and economic impacts.

Our main goal is to improve Volcanic Ash Transport and Deposition Models (VATDMs) of dispersing volcanic plumes, by explicitly tackling the "most pressing challenge" for accurate hazard forecasting - a better characterisation of the eruption source term. The project will enable improved operational ash forecasts, thus resulting in academic, societal and economic impact with global reach.

Improved VATDMs will increase the effectiveness of operational public services such as the UK Met Office, VAACs, CAA (in the UK), the US Geological Survey (USGS) and civil defence organisations and disaster emergency response organisations worldwide. Improved models will enhance disaster planning through scenario-testing simulations (for volcanic and other plumes, e.g. from forest fires). This will lead to improved mitigation of volcanic ash hazards such as air/water pollution, agricultural contamination and infrastructure damage, and potentially to policy changes such as ICAO operational procedures for air traffic operations near volcanic eruptions. Building capability for improved operational ash forecasts will minimise disruption and optimise the mitigation response to volcanic plumes internationally. With air travel continuing to increase, and economic losses due to airspace closure from the 2010 Eyjafjallajökull eruption estimated at US$5B, this is a key economic driver, for the UK and worldwide; optimised responses will minimise economic loss at the international scale, reduce economic impact on individual businesses at national scale, and reduce impact on individuals at the local scale.

In the longer term, we will deliver impact through our multi-frequency radar technique enabling 3D plume imaging and providing critical data needed to understand the processes occurring within evolving plumes (e.g. particle aggregation) and to develop the next generation of VATDMs. However, our results, inversion strategies and retrieval algorithms will be of immediate relevance to meteorologists and other atmospheric and remote sensing scientists researching particulates in the environment, including dust and smoke plumes from forest fires. Our results will also guide use of existing radar systems for better determining plume properties, and will inform the development and acquisition of new systems, with implications for radar researchers, manufacturers and operational users. Our new characterisation of ash scattering properties will enable immediate improvement of current radar interpretations to deliver more accurately defined volcanic plume source term parameters, and thus improved VATDM outputs. The transfer of our multi-frequency retrieval algorithms to operational use would be a successful exploitation of scientific knowledge.

The project will develop five PDRA researchers, some of whom already demonstrate accomplished profiles, into leading young researchers with cross-disciplinary skills in hazard modelling and remote sensing of atmospheric particulates. With a network of international academic and applied (i.e. operational) collaborators, they will represent a body of expertise uniquely placed to make a substantial contribution to UK and global geohazard resilience, as well as to other areas of science.

Through outreach work, the project will increase public understanding of the internationally leading research being conducted in the UK. Outreach will be focussed on delivering a better understanding of the hazards and risks associated with ash clouds so that the importance of improved accuracy of ash forecasts is appreciated. Our project embeds links with VAACs who are responsible for aviation hazard forecasting and the USGS, with their connections to national public policy and management of natural hazards, to ensure that the research benefits to society will be realised globally.