Space weather disruptions to satellite navigation and telecommunications: ionospheric scintillation

Lead Research Organisation: University of Bath
Department Name: Electronic and Electrical Engineering

Abstract

The modern world is increasing reliant on systems that make use of Global Navigation Satellite Systems (GNSS), perhaps the most well know of which is GPS. These include the 'Satnav' in cars or mobile phones. However, in addition to its use in transport (road, air, rail and maritime), GNSS is used a wide range of other applications including surveying, emergency services, agriculture, mobile communications and financial transactions. In a 2011 report from the Commission to the European Parliament and the Council it was estimated that 800 billion euro of gross domestic product (GDP) in the European Union, was then dependent on satellite radio navigation. A Royal Academy of Engineering report of the same year suggested that Services that depend on GNSS for positioning, navigation or timing (PNT), either directly or indirectly, "should document this as part of their service descriptions and explain their contingency plans for GNSS outages".

We will provide, to our partners, global maps of risk of such outages, caused by ionospheric scintillation, a major result of space-weather affecting the ionosphere. Scintillation is where there are such rapid changes in the radio signal from a GNSS satellite that a receiver cannot 'lock on' to the signal and so cannot use this signal for navigation or timing. Scintillation is common at both high and low latitudes, but can on occasions extend to middle latitudes such as the UK, Europe and the United States. For example, during the 'Halloween' solar storm in October 2003, the United States Federal Aviation Administration Wide-Area Augmentation System (WAAS) network for air navigation was disabled for 30 hours, primarily due to scintillation. Our work is timely as the use of GNSS is so ubiquitous that a recent (June 2017) Innovate UK report estimated that the impact in the UK alone to a five-day disruption to GNSS would be in excess of £5 billion through direct losses and knock-on delays caused. £110 million of this was in the railector, an area of particular interest to our project partners.

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/619544/17.3254_Economic_impact_to_UK_of_a_disruption_to_GNSS_-_Full_Report.pdf

http://lasp.colorado.edu/home/wp-content/uploads/2011/07/lowres-Severe-Space-Weather-FINAL.pdf

http://www.raeng.org.uk/publications/reports/global-navigation-space-systems

Planned Impact

The objective of this project is to transfer knowledge to industrial partners on the likelihood and severity of disruptions introduced by scintillation during adverse space weather conditions on infrastructure relying upon satellite telecommunications and navigation over a global scale as well as on the systems interdependencies.

This project will provide advice on possible mitigation strategies and countermeasures in accordance with risk maps that can contribute to contingency plans. For example, technical specifications of minimum requirements of radio receivers, best practice to operate radio receivers, optimal methods to minimise accuracy degradation on precise point positioning and differential positioning.

Through the knowledge gained from this project, the project partners will be able to: (a) assess risks for industrial operations and services vulnerable to ionospheric scintillation; (b) inform their clients and decision-makers on best practices to minimise risks; (c) effectively and successfully manage emergency crises; (e) improve their short and long-term investment decisions, minimising costs arising from services outages introduced by scintillation associated with adverse space weather.

Publications

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Description This project has developed an innovative method to quantify and characterise the effects and disruptions that adverse space weather conditions can have on ground users relying upon satellite navigation (for example, precise positioning and timing).

This is aimed at benefitting typical users of Global Navigation Satellite Systems - GNSS (e.g. GPS, Galileo). To this purpose, the innovative method is able to:
1) Quantify the risk associated with ionisation structures during adverse space weather conditions through a probabilistic approach from decision theory;
2) Quantify the impact that adverse space weather conditions have on ground positioning and timing through "bubble plots" that show the magnitude of the positioning error, the variance of the timing error and the probability of occurrence of GNSS outages.

Two manuscripts are being prepared and will be submitted for publication.

The project illustrated how traditional space weather information (e.g. maps of Total Electron Content) does not meet the users' quest for information about what exactly the impact can be on their systems.
This method fulfils the translational spirit of the project: it provides industrial users with information they actually need in order to operate their systems (particularly, in safety-critical applications such as autonomous navigation).
Exploitation Route The methodology developed within this project originated from discussions with the industrial partners. Their input led to the development of a probabilistic methodology that quantifies the impact on satellite positioning, navigation and timing for users on the ground, during adverse space weather conditions.
This methodology forms the basis for the real-time monitoring as well as forecasting of risks and impact during adverse space weather conditions on ground infrastructure relying upon satellite navigation. The methodology is entirely aimed at users of satellite navigation and translates scientific observations into practical and tangible aspects (e.g. occurrence of outages).
The methodology can be implemented on any platform aimed at real-time monitoring and forecasting and the team would be very happy to contribute to that objective.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Energy,Environment,Financial Services, and Management Consultancy,Government, Democracy and Justice,Transport