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THE INFLUENCE OF SPACE WEATHER ON HIGH PRECISION POSITIONING IN THE NORDIC REGION Bo Jonsson Lantmäteriet, National Land Survey of Sweden bo.jonsson@lm.se www.swepos.com Co-authors: Gunnar Hedling, Lantmäteriet Jan Johansson, Chalmers university of Technology. Contents.
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THE INFLUENCE OF SPACE WEATHER ON HIGH PRECISION POSITIONING IN THE NORDIC REGION Bo Jonsson Lantmäteriet, National Land Survey of Sweden bo.jonsson@lm.se www.swepos.com Co-authors: Gunnar Hedling, Lantmäteriet Jan Johansson, Chalmers university of Technology
Contents • Surveying techniques - overview • Sunspot maximum 1989 • Sunspot maximum 2000 • Next sunspot maximum - expectations
Surveying using GPS (2) Regional Positioning Service 0,5 - 5 centimeter
Position Tailor madeRTK data SWEPOS™ - a Swedish network of reference stations SWEPOS control centre in Gävle SydS SydM SydN NordN Reference-station data Position
Other GPS applications Measurements at sea, Picture; Marin mätteknik Machine guidance, Picture; PEAB Swedish Maritime Administration Agricultural applications
Sunspot Maximum 1989 (1) • Conditions: • Few GPS-receivers (<20) • Single frequency receivers • Primitive receiver technology • Only post-processing • Short baselines (<10 -20 km)
Sunspot maximum 1989 (2) • Impacts: • Some days difficulties to get “fixed solutions” • Solutions: • Shorter baselines if possible • Re-measurement another day
Forecast of geomagnetic activities from Geological Survey of Canada
Sunspot maximum (2000) • Conditions: • GPS had been introduced in the Surveying community (larger number of receivers ) • Both post-processing and real-time positioning • Dual-frequency receivers • More advanced receivers • Pilot projects for Network-RTK
Sunspot maximum 2000 (2) • Impacts: • Some days difficulties to get “fixed solutions” both for post-processing and real-time • “False” fixed solutions • Solutions: • Shorter baselines if possible • Re-measurement next day
Estimation of Ionospheric index I95 at SWEPOS control center
Ionosphere Autumn 2003 (2) • 28 October and 4 November 2003 enormous flares were ejected by the sun. • The 28 October flare made it impossible to measure with Network RTK for 2 days in Sweden! • The 4 November flare only caused small disturbances in Sweden!
Forecast of geomagnetic activities from Geological Survey of Canada
Pre-study Network-RTK Projects 2000-2001 (Positioning Service) Position Stockholm Mälaren (Jan-May 2001) • Users from Governmental Agencies and Local Authorities • GPSnet and Cellular phone (GSM) Result: • Very promising • Prototype Production Networks should be established Stock-Mäl New-RTK SKAN-RTK
Sunspot maximum 2000 (3) The last sunspot maximum didn’t stop the development of Network RTK because: • It was rather mild. • Network RTK proved itself to be a robust technique! • The I95 Index was built into GPSNet! • Many available Space Weather websites.
The next sunspot maximum 2011? • Improved signal processing in the user equipment? • Increased number of satellite signals (GLONASS, L2C, L5)? • SWEPOS provides ionospheric index I95 in real time to the users via SWEPOS web-site • A reliable space weather forecast service for high precision positioning using GNSS should be beneficial?
Space weather forecast service for the next sunspot maximum 2011 • The best model of a Space Weather forecast is of course a standard weather forecast. • The length of a magnetic storm is very important – a couple of hours to days • The user shall get the information day by day if he can expect a successful GNSS positioning before he start his work in the field • To have some hint about this would be most useful.
Conclusion One important issue for high precision positioning applications using GNSS techniques during the next sunspot maximum period is a reliable Space Weather Forecast Service which tells the user day by day if he can expect a successful GNSS positioning