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 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

PositionTailor made

RTK data

Reference-station data

NordNSydS SydM SydN

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 Activity Autumn 2003 (1)

Oct-Nov 2003 Max Planetary Index and EPN ambiguity resolution percentage

0

20

40

60

80

100

Date

Per

cen

t an

d 1

0xP

l in

dex

Serie1

Serie2

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

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!