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The effect of space weather on maritime aids-to-navigation service provision

Grant A., Shaw G., Ward N.

Annual of Navigation

2012

No. 19, part 1

49--66

The General Lighthouse Authorities of the United Kingdom and Ireland (GLA) provide marine Aids-to-Navigation (AtoNs) for the benefit and safety of all mariners within their waters. These AtoNs include traditional lighthouses, buoys and various radionavigation systems. It is recognised that GPS, or more generally Global Navigation Satellite Systems (GNSS), have become the primary means of obtaining Position, Navigation and Timing (PNT) information at sea. Mariners may have come to believe that GPS is infallible, yet it is known to be vulnerable to solar activity, interference and system failures. The Sun continuously releases random bursts of energy and highly charged particles. The impact of these emissions on the Earth is known as space weather. Bursts of electromagnetic energy can result in radio blackouts; bursts of high energy particles can increase ionising radiation and affect space craft performance; and bursts of magnetised plasma can result in the degradation and potential loss of radionavigation signals on Earth. The amount of solar activity is linked with the natural sunspot cycle, which shows the number of sunspots peak approximately every 11 years, with the next peak due in 2013. Sunspots occur almost continuously, but normally give rise to weak solar events that generally go by unnoticed. However significant storms can occur at any time and as we approach peak activity, the number of space weather events will increase. AtoNs generally report their position using radio systems, whether through the Automatic Identification System (AIS), public networks or dedicated links; and often use GNSS to calculate their position and to obtain timing information. Mariners use GNSS for PNT information; with this information integrated into many different bridge systems. Powerful solar storms can affect GNSS performance and the reception of their signals, which may lead to different correlated events, both on and off the ship. During very extreme and very rare storms, national power systems may be switched off to protect the infrastructure which would clearly affect those services relying on mains power without backup. This paper reports the output of a study into the potential effects of space weather on GLA AtoN service provision and presents mitigating actions, where appropriate. The outcome of this study will help the GLA to continue to provide the highest level of AtoN availability, helping to ensure the safety of all mariners.

DGNSS Re-Capitalization

Pattinson M., Dumville M., Ward N.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2007

Vol. 1, no. 1

47--53

The General Lighthouse Authorities (UK & Ireland) DGPS service came into operation in 1998. In common with other maritime DGPS services the equipment will need replacement over the next few years, in fact computing and communications equipment have already been replaced. Replacement of existing hardware with similar, dedicated Reference Stations and Integrity Monitors (RSIM) is the baseline option and will form a fallback plan if other options prove not to be feasible. However, the choice of suppliers is limited and once chosen, it would be difficult to diversify. Three other options can be identified: software RSIM, Virtual Reference Station (VRS) and integration with Satellite Based Augmentation Systems (SBAS). The software RSIM option draws on the experience of the United States Coast Guard. The VRS and SBAS integration options are treated as potential alternatives to an onsite hardware or software RSIM, but the possibilities of combining either or both with the software RSIM are also considered. All options took into account the need for validation of system performance. This paper draws conclusions about feasibility, performance, risks and costs of the different options and makes recommendations on the course to adopt.