Solar Flares and OS Net ? the impact on GPS? - Ordnance Survey ...

Space weather is once again in the news ? with a big solar flare hitting Earth this morning.

Solar flares are related to sunspot activity which tends to run in 11 year cycles. We?re now in the period where sunspot activity is increasing to a maximum for the current cycle. This morning?s flare is the biggest for 5 years ? and tonight there is a chance Scotland might even get to experience the Northern Lights as a result.

However 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).

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In the context of OS Net, our national network of 110 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.? Space weather is also bad news for users who derive accurate timing from GNSS such as to synchronise computer and communications networks.

During a space weather event, GNSS users may experience a loss of satellite signal or errors in position or timing. Using a network of? dual frequency 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 250 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 and the people who rely on our data, as possible.

The data from a national network of high precision, dual frequency receivers such OS Net is also useful to predict and monitor the impacts of space weather on the positioning and timing community, these receivers are capable of directly measuring the?ionospheric delay of the satellite signals as they?travel down to earth ,?unlike standard GPS receivers.?Ordnance Survey are also a partner in SENTINEL ? a Technology Strategy Board sponsored research project to monitor the impact of such things as space weather on GNSS signals.? The data collected by OS Net stations and SENTINEL ?probes? across the country during today?s event will make an important contribution to the research in to the impacts of space weather on GNSS signals.

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

Source: http://blog.ordnancesurvey.co.uk/2012/03/solar-flares-and-os-net-the-impact-on-gps/

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