DETERMINING AND PREDICTING THE SIZE AND ONSET TIMES OF SUBSTORMS

The Sun's influence on the Earth goes well beyond gravitational attraction and shiny light and heat down on the Earth's surface; the Sun and Earth are connected by a stream of charged particles that is constantly flowing off the Sun and becoming trapped in the Earth's magnetic field. These charged particles bring with them the Sun's magnetic field, which can join up with the Earth's field, causing those trapped charged particles to become energised and to fly along the Earth's magnetic field into the atmosphere. When these particles hit the atmosphere, they cause it to glow in spectacular light displays that we call the aurora.

The Earth is protected from most of the particles coming off the Sun by its magnetic field. As it expands out into space, it is deformed by the charged particles flowing off the Sun impacting upon it. It forms a bullet-like shaped region extending 60,000 km in front of the Earth, and over 600,000 km behind the Earth and known as the magnetosphere. As the solar particles and magnetic field hit the magnetosphere, it absorbs energy, storing that energy in the magnetic field behind the Earth. This store of energy is unstable, and eventually it is released, energising charged particles in the magnetosphere to create bright aurora in a process known as a substorm. These substorms happen three to four times per day, lighting up the night sky in the northern and southern polar regions for hours on end. To an observer in the right place on the ground, the whole of the night sky will light up over half-an-hour, before slowly fading for another hour or so.

Whilst displays of substorm aurora are stunningly beautiful, they are far from benign. The particles associated with them can drive extremely large currents through the atmosphere that can cause other currents to flow on the ground. These currents can cause damage to electrical equipment and power networks, potentially leading to blackouts across large swathes of the Earth's surface. The energisation of charged particles in space can be hazardous to spacecraft, potentially causing millions of pounds worth of damage in a matter of seconds. As such, in a world that is increasingly reliant on space-based and electrical technology, these substorms represent a very real risk. Scientists also believe that these events can cause changes in the upper atmosphere that can affect its chemistry and potentially impact on climate, but as yet this effect is poorly understood owing to a lack of necessary observations.

Despite being known about for thousands of years and studied in detail since the turn of the last century, we still are unable to accurately predict when and where these space weather events will occur. This is a major hurdle in space weather science that has remained a problem in this field due to a combination of lack of data and lack of the necessary tools to properly analyse this data. However, we are now in the best position to date to address these issues. The new research proposed in this project will combine datasets that have been collected over the last 20 years and answer the questions "when will these events occur?", "what will their impact be?" and "what controls them?". By answering these questions, we will be able to understand what we need to know in order to predict when these events will occur and what there impact will be.

As discussed in the Academic Beneficiaries and Pathways to Impact, there are numerous academic institutes and industrial stakeholders who will benefit from this research. Understanding the substorm cycle and the processes that govern the start, end and size of substorms is of fundamental importance to those academics studying the individual physical processes in substorms and modelling the coupled solar-terrestrial system. Furthermore, the ability to predict the timing and impact of substorms and understand the space weather impact of these events will have benefits to a wide range of industry and government departments.

Academic Impact
The underlying controlling factors of substorm activity in the coupled solar-terrestrial system have remained a mystery due to previous inabilities to definitively identify all aspects of substorms. The research proposed in this fellowship will address this and thus will be of interest to the immediate substorm research community, as well as the wider space plasma and space weather research communities. Furthermore, in the medium term this interest may be of interest to the wider astronomical community in assisting to understand the impact of substorms on the ionosphere and thus their effect on radio telescope observations. The short term academic impact will be realised through the publication of research papers in high-impact international peer-reviewed journals, with these papers made open-access in accordance with NERC and UCL policy. This will enhance the knowledge economy through new scientific advances in this field.

Additionally, through undertaking this fellowship at UCL, I will be in a position to supervise undergraduate, post-graduate and PhD students thus delivering and training highly skilled researchers with a diverse skill set suitable for academia and with wider business sectors.

Industrial Impact
Space weather events are now recognised as a medium impact, high likelihood to the UK economy and society and are accordingly included in the UK National Risk Register. Examples of those industries at risk to the effects of substorm activity include: the oil and gas sectors, through magnetic drilling and surveying operations; the power sector, through the risk of damage from geomagnetically induced currents (GICs); the rail sector, through GICs and communication breakdowns; satellite operates, through damage from charged particles and single event upsets. By providing a predictive model of substorm sizes, times and impacts and through working with space weather stakeholders, such as the British Geological Survey and UK Met Office, this research will provide a pathway to the reduction of risk from these events that will enhance the efficiency and performance of industry and will inform evidence-based policy decisions on dealing with the impact of space weather.

Social Impact
Throughout this fellowship, I will seek to engage with the public on the topic of space weather and wider science topics. Through producing high-impact research in an area of keen public interest and publicising this work through press releases and social media, I will enhance public knowledge. By doing this, and continuing to be involved in careers outreach events for school and college leavers, I will encourage future generations to undertake careers in highly-skilled science and engineering industries.