What is ‘space weather’? Well this generally means solar flares – or as you might have heard on the news recently – coronal mass ejections to give them their full title!

Solar flares are related to sunspot activity which tends to run in 11 year cycles. We’re now entering the period where sunspot activity is increasing to a maximum for the current cycle. On Tuesday there was a big flare – the biggest for 4 years - whilst tonight those of you in Scotland might even get to see the Northern Lights as a result, so keep your eyes on the skies!

A solar flare

So what’s all this got to do with mapping?

Solar flares can disrupt electromagnetic communications especially ones involving satellites. Solar flares increase the electromagnetic activity in a part of the Earth’s atmosphere called the ionosphere. This increases the impact of the ionosphere on GNSS signals (the generic term for all the navigation satellites orbiting the Earth, like GPS).

In the context of OS Net, our network of satellite receiver stations that make precision map making possible, a period of bad ‘space weather’ can make our work much more difficult. It makes satellites harder pick up and track from the ground. Also, in order to calculate an accurate position, the effect of the ionosphere must be modelled and then removed.

When ionospheric activity is high and changing rapidly (like it is at the moment) this modelling is much more difficult.

During a space weather event, sat nav users may experience a loss of satellite signal or errors in position. During the last big solar storm in October 2003 position shifts of greater than 10cm horizontal and up to 26cm vertical were recorded in higher latitude northern Europe – not such a big deal for drivers, but that it makes map making a lot more difficult!

Using a network of satellite receiver stations, like OS Net, as opposed to a single base station solution is the best way to mitigate the effects of bad space weather. Processing data from a network of base stations allows for the best possible real time modelling of the changing effect of the ionosphere. This means more robust data is sent to our 300 surveyors working to map the changes across the country.

In the meantime, we’re working hard to make sure the affects of this current  period of bad weather have as little impact on our work, the people who rely on our data, as possible.

There is some more information on solar flares from the British Geological Survey, whilst if you’re after a more technical article on the impact of space weather on GNSS can be found here.

Mark is a Geodetic Analyst at Ordnance Survey.

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