THE INFLUENCE OF SPACE WEATHER ON HIGH PRECISION POSITIONING IN THE NORDIC REGION Bo Jonsson Lantmäteriet, National Land Survey of Sweden 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 before GPS

Surveying using GPS (1)

Regional Positioning Service 0,5 - 5 centimeter Surveying using GPS (2)

SWEPOS™ - a Swedish network of reference stations SWEPOS control centre in Gävle Position Tailor made RTK data Reference- station data NordNSydSSydMSydN

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 (< 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 Activity Autumn 2003 (1)

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 (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 New-RTK SKAN-RTK Stock- Mäl

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

Many thanks for your attention!