Fire is the most important disturbance agent worldwide in terms of area and variety of biomes affected, a major mechanism by which carbon is transferred from from the land to the atmosphere, and a globally significant source of aerosols and many trace gas species. Forecasting of fire risk is undertaken in many fire-prone environments to aid dry season pre-planning, and appropriate consideration of fire is also required within dynamic vegetation models that aim to examine vegetation-climate interactions in the past, present and future. Current methods of mapping fire 'risk', 'susceptabilty' or 'danger' use empirical fire danger indexes calibrated against past weather conditions and fire events. As such, they provide little information on process, are appropriate to deal only with current climate, land use and land cover change (LULCC), and are limited in their ability to be tested and constrained by EO products or other observational data (e.g. ignition 'hotspots', burned area, pyrogenic C release etc). The objective of FireMAFS is to resolve these limitations by developing a robust method to forecast fire activity (fire danger indices, ignition probabilities, burnt area, fire intensity etc) via a process-based model of fire-vegetation interactions, tested, improved, and constrained using state-of-the-art EO data products and driven by seasonal weather forecasts issued with many months lead-time. Specific aims are to: (i) develop the methodology for using EO and other observational data on vegetation (fuel) condition, fire activity and fire effects to test, improve and constrain sub-components and end-to-end predictions of a forward model of fire-vegetation interactions and to inform, test and restrict the model when used in forecast mode to ensure it is nudged along the optimum trajectory, and is furthermore reset when the observation period catches up with the prior period of prediction; (ii) drive the improved forward model by seasonal weather forecast ensembles, predicting spatio-temporal variability in fire 'danger' indices, fire occurrence and a range of subsequent fire behaviour and fire effects (intensity, rate of spread, burned area, above/below ground C stock change, and trace gas/aerosol emissions) and evaluate their usefulness for seasonal fire prediction at 1 / 6 months lead time and for prognostic studies run under future projected climate and LULCC scenarios.

The Greenland Ice Sheet is the world's largest single source of barystatic sea-level rise (c.20% total rise) and more than half of the mass lost annually from the ice sheet comes from surface melt-water runoff. This proportion, and its magnitude, is rising with continued climate warming but future projections, and societal planning for sea level rise impacts, are undermined by a fundamental source of uncertainty. Across the vast majority of the accumulation area of the Greenland Ice Sheet, we do not know how much of the water produced from surface melting refreezes in underlying firn (i.e. multi-year snow) or becomes runoff. When the surface of an ice sheet melts, the density and temperature of underlying snow, firn and impermeable ice combine to determine whether melt refreezes in the underlying snow and firn, or becomes runoff to the ocean. If meltwater can percolate to depth (e.g. up to c.10 m) and access cold, low density firn, it can refreeze creating a significant buffer between climate change and sea-level rise. Alternatively, if melt encounters shallow impermeable ice layers (themselves created by previous refreezing) within relatively warm firn, melt cannot reach the cold firn and more melt will become runoff. The difference between these two scenarios alone could double ice sheet runoff by the middle of the 21st century. We rely on model simulations of surface melt, refreezing and runoff to accurately project the future contribution of the Greenland Ice Sheet to sea level rise. However, model-based estimates of the annual refreezing capacity of the ice sheet over the last six decades differ dramatically and undermines their ability to converge towards a reliable range of future projections. A major cause of uncertainty follows from the quite different assumptions that models make about ice layer permeability that dramatically alters the ice sheet refreezing capacity. If ice layers in firn are assumed to be impermeable (permeable), they will inhibit (allow) meltwater percolation to depth, diminish (maintain) refreezing capacity, increase (decrease) runoff and hence increase (decrease) projected global sea level rise. Without an improved treatment of ice layer permeability, existing surface mass balance models cannot provide reliable projections of the future refreezing capacity of, and melt-water runoff from, the Greenland Ice Sheet, leaving the ice sheet's future contribution to sea level rise highly uncertain. Firstly, we need to know the physical and thermal conditions of snow and firn that control the effective permeability of relatively thin ice layers (<0.5m thick) since within our warming climate these are increasingly determining the depth to which meltwater can percolate and hence control the refreezing capacity of the underlying firn. To this end we will undertake temperature-controlled laboratory experiments, systematically simulating and monitoring snow/firn/ice melt/refreezing/runoff. Secondly, we need to model the effective permeability of ice layers in snow and firn and their sensitivity to changing external and internal conditions since these together control how much melt refreezes or becomes runoff. For this, our lab work will inform novel developments to modelling to simulate measured arctic ice cap snowpack evolution. Finally we will incorporate improved ice layer permeability criteria within ice sheet scale models of the Greenland Ice Sheet to generate more accurate simulations of runoff and refreezing during melt extremes and improve harmonisation of long-term mass balance model projections, consequently improving global sea level rise predictions over the next century. Multiple recent "exceptional" melt seasons have caused near surface ice layers to proliferate through previously low density firn. These extremes will be the new norm in the future so new model parameterisations are urgently required that can effectively characterise ice layer control on mass balance.

Efficient air traffic management depends on reliable communications between aircraft and the air traffic control centres. However there is a lack of ground infrastructure in the Arctic to support communications via the standard VHF links (and over the Arctic Ocean such links are impossible) and communication via geostationary satellites is not possible above about 82 degrees latitude because of the curvature of the Earth. Thus for the high latitude flights it is necessary to use high frequency (HF) radio for communication. HF radio relies on reflections from the ionosphere to achieve long distance communication round the curve of the Earth. Unfortunately the high latitude ionosphere is affected by space weather disturbances that can disrupt communications. These disturbances originate with events on the Sun such as solar flares and coronal mass ejections that send out particles that are guided by the Earth's magnetic field into the regions around the poles. During such events HF radio communication can be severely disrupted and aircraft are forced to use longer low latitude routes with consequent increased flight time, fuel consumption and cost. Often, the necessity to land and refuel for these longer routes further increases the fuel consumption. The work described in this proposal cannot prevent the space weather disturbances and their effects on radio communication, but by developing a detailed understanding of the phenomena and using this to provide space weather information services the disruption to flight operations can be minimised. The occurrence of ionospheric disturbances and disruption of radio communication follows the 11-year cycle in solar activity. During the last peak in solar activity a number of events caused disruption of trans-Atlantic air routes. Disruptions to radio communications in recent years have been less frequent as we were at the low phase of the solar cycle. However, in the next few years there will be an upswing in solar activity that will produce a consequent increase in radio communications problems. The increased use of trans-polar routes and the requirement to handle greater traffic density on trans-Atlantic routes both mean that maintaining reliable high latitude communications will be even more important in the future.

Fire is the most important disturbance agent worldwide in terms of area and variety of biomes affected, a major mechanism by which carbon is transferred from from the land to the atmosphere, and a globally significant source of aerosols and many trace gas species. Forecasting of fire risk is undertaken in many fire-prone environments to aid dry season pre-planning, and appropriate consideration of fire is also required within dynamic vegetation models that aim to examine vegetation-climate interactions in the past, present and future. Current methods of mapping fire 'risk', 'susceptabilty' or 'danger' use empirical fire danger indexes calibrated against past weather conditions and fire events. As such, they provide little information on process, are appropriate to deal only with current climate, land use and land cover change (LULCC), and are limited in their ability to be tested and constrained by EO products or other observational data (e.g. ignition 'hotspots', burned area, pyrogenic C release etc). The objective of FireMAFS is to resolve these limitations by developing a robust method to forecast fire activity (fire danger indices, ignition probabilities, burnt area, fire intensity etc) via a process-based model of fire-vegetation interactions, tested, improved, and constrained using state-of-the-art EO data products and driven by seasonal weather forecasts issued with many months lead-time. Specific aims are to: (i) develop the methodology for using EO and other observational data on vegetation (fuel) condition, fire activity and fire effects to test, improve and constrain sub-components and end-to-end predictions of a forward model of fire-vegetation interactions and to inform, test and restrict the model when used in forecast mode to ensure it is nudged along the optimum trajectory, and is furthermore reset when the observation period catches up with the prior period of prediction; (ii) drive the improved forward model by seasonal weather forecast ensembles, predicting spatio-temporal variability in fire 'danger' indices, fire occurrence and a range of subsequent fire behaviour and fire effects (intensity, rate of spread, burned area, above/below ground C stock change, and trace gas/aerosol emissions) and evaluate their usefulness for seasonal fire prediction at 1 / 6 months lead time and for prognostic studies run under future projected climate and LULCC scenarios.

Fire is the most important disturbance agent worldwide in terms of area and variety of biomes affected, a major mechanism by which carbon is transferred from from the land to the atmosphere, and a globally significant source of aerosols and many trace gas species. Forecasting of fire risk is undertaken in many fire-prone environments to aid dry season pre-planning, and appropriate consideration of fire is also required within dynamic vegetation models that aim to examine vegetation-climate interactions in the past, present and future. Current methods of mapping fire 'risk', 'susceptabilty' or 'danger' use empirical fire danger indexes calibrated against past weather conditions and fire events. As such, they provide little information on process, are appropriate to deal only with current climate, land use and land cover change (LULCC), and are limited in their ability to be tested and constrained by EO products or other observational data (e.g. ignition 'hotspots', burned area, pyrogenic C release etc). The objective of FireMAFS is to resolve these limitations by developing a robust method to forecast fire activity (fire danger indices, ignition probabilities, burnt area, fire intensity etc) via a process-based model of fire-vegetation interactions, tested, improved, and constrained using state-of-the-art EO data products and driven by seasonal weather forecasts issued with many months lead-time. Specific aims are to: (i) develop the methodology for using EO and other observational data on vegetation (fuel) condition, fire activity and fire effects to test, improve and constrain sub-components and end-to-end predictions of a forward model of fire-vegetation interactions and to inform, test and restrict the model when used in forecast mode to ensure it is nudged along the optimum trajectory, and is furthermore reset when the observation period catches up with the prior period of prediction; (ii) drive the improved forward model by seasonal weather forecast ensembles, predicting spatio-temporal variability in fire 'danger' indices, fire occurrence and a range of subsequent fire behaviour and fire effects (intensity, rate of spread, burned area, above/below ground C stock change, and trace gas/aerosol emissions) and evaluate their usefulness for seasonal fire prediction at 1 / 6 months lead time and for prognostic studies run under future projected climate and LULCC scenarios.