European Incoherent Scatter Radar Facility (EISCAT) - UK Support

EISCAT_3D is an international collaboration that will deliver a new world-leading radar in Europe to monitor and improve understanding of the atmosphere and space weather. It will also provide essential validation for models of the whole atmosphere and for forecasting space weather, which are currently under development.

Space weather is the term used to describe natural changes in the upper atmosphere and near-space environment driven by energy from the Sun. As our technology advances and science, industry, and society rely more and more on satellite technology, so our vulnerability to space weather increases. Extreme space weather, which features on the UK Government's 2015 National Risk Register, can cause serious damage to satellites and their associated services, as well as to other critical infrastructures such as power grids and aviation. Long-term trends in space weather also affect the strategies and policies required to protect satellites from the hazards of collision with space debris. However, space weather cannot yet be reliably forecast. To do so requires scientific research to improve understanding and develop improved forecasting models, and better data to inform the research and validate the models.

Space weather in the upper atmosphere is influenced by the atmosphere below and there is increasing evidence that space weather also affects "ordinary" weather in the lower atmosphere. The different layers of the atmosphere, from the ground to the edge of space, form a complex coupled system, connected by a wide variety of chemical and dynamical processes, such that it is impossible to understand any one layer of the atmosphere in isolation. Models of the whole atmosphere are now being developed, but there are many processes and feedbacks between layers that are not yet well enough understood to accurately explain or predict their effects.

Thus to understand space weather and predict its hazards, and to understand it in the context of the whole atmospheric system, requires a sensitive and versatile instrument that can measure as much of the atmosphere as possible, with good altitude and time resolution over a broad spatial area, in order to study both vertical coupling between atmospheric layers and horizontal structure on the scales affecting individual satellites, planes, and national power grids. EISCAT_3D's new radar technology, combined with the latest digital signal processing, will achieve ten times higher spatial and temporal resolution than the radars it will replace while simultaneously offering, for the first time, continuous measurement capabilities and 3-D imaging. Building on the UK's world-leading expertise in space weather research and its membership of the EISCAT Scientific Association over the last 30 years, this new capability will help address three key scientific challenges (see Objectives):

1. To understand the natural processes behind observed variabilities and trends in the upper atmosphere.
2. To develop and validate space weather forecasting models comparable to those in meteorology.
3. To improve and validate computer models of the whole atmosphere.

UK Government
"Satellites and Commercial Applications of Space" is one of the 8 Great Technologies in the Government's industrial strategy, recognising the strong economic growth of a sector worth over £9 billion a year to the UK economy. The Government's National Space Security Policy (April 2014) has an objective to "make the United Kingdom more resilient to the risk of disruption to space services and capabilities, including from space weather" and "from the growing threat to satellite operations from space debris". In the associated Space Weather Preparedness Strategy (July 2015), the Department for Business, Energy and Industrial Strategy (BEIS) is identified as the owner of the risk to the UK from severe space weather.

Supported by a £4.6M investment from BEIS, the Met Office Space Weather Operations Centre (MOSWOC) provides a round-the-clock service of space weather alerts and warnings of potential impacts to governmental and commercial stakeholders. MOSWOC supports the UK investment in EISCAT_3D, to enable the research required for improved forecasts of the ionosphere and thermosphere (see attached Letter of Support). This includes the extension of the Met Office's weather and climate model up to the thermosphere, where EISCAT_3D data would play an important role in its development, testing and verification. The benefits of EISCAT_3D research and data to commercial stakeholders are anticipated to be delivered primarily through MOSWOC, but other interactions between academia and business sectors are expected. Examples include:

Satellite operators
In the thermosphere between 85 and 1000 km altitude, there are thousands of orbiting satellites worth billions of pounds providing essential modern services including satnav, satcomms, and remote sensing. There are also over 500,000 pieces of orbiting space debris larger than 1 cm at risk of colliding with the satellites, causing significant damage or destruction. Space weather is the greatest source of uncertainty in forecasting this risk because it continually alters the relative locations of both satellites and debris by heating the upper atmosphere and changing the drag on these objects. Over longer time scales, this drag also causes a satellite altitude to continually decay until it eventually burns up in the atmosphere. Thus anomalous heating by space weather will cause an unexpectedly premature end to satellite operations, while anomalous cooling allows satellites and space debris to stay longer in orbit, making space more crowded and increasing the risk of collisions. EISCAT_3D will improve the understanding and forecasting of satellite-debris collisions because it can both measure the space weather influences and the trajectories of satellites and debris.

Satellite services
The economy and society are increasingly dependent on Global Navigation Satellite Systems (GNSS) such as GPS for providing precise positioning used by transport, emergency services, agriculture, etc. Position is determined from measurements of the transit times of radio signals from several satellites at different locations. Space weather adversely affects GNSS accuracy and provision by changing the ionosphere through which the radio signals pass, altering their transit times or even occasionally absorbing the signals entirely. The 3-D imaging and high resolution of EISCAT_3D will allow us to see variations in electron density in the ionosphere on multiple scales, improving understanding of how they affect the GNSS radio signal and of the space weather conditions and plasma instabilities that cause them.

National Grid
Varying electrical currents in the ionosphere induce potentially hazardous currents in the National Grid. Whilst large-scale currents can be predicted to some degree, the hazard likely comes from rapidly-varying smaller-scale currents that are poorly understood. EISCAT_3D has the resolution to investigate their properties and their relationship to the larger scale.