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SWEREF 99

SWEREF 99 is the official reference frame used in Sweden today.

SWEREF 99 stands for Swedish Reference Frame 1999 and is a realization of the European reference system ETRS89.

The relation to WGS 84

WGS 84 and SWEREF 99 differ by 78 dm for the time being (2021); increasing with time as the European plate moves. Thus SWEREF 99, WGS 84 and the previous frame SWEREF 93 can be interchangeable for many applications.

Read more about the relation between SWEREF 99 and WGS 84.

Computation of SWEREF 99

SWEREF 99 is a realization of ETRS89, performed in accordance with the EUREF guidelines, and was adopted as an improvement and extension of ETRS 89 at the EUREF Symposium held in Tromsø, 2224 June 2000.

Map of the Nordic and Baltic countries, showing the reference stations  of the SWEREF 99 campaign.
Red dots show the defining stations of the SWEREF 99 campaign. The other stations in the campaign are shown in black.

SWEREF 99 was originally defined by the 21 original Swepos stations the so-called fundamental stations monumented with pillars on stable bedrock. The permanent stations Sweden (Swepos), Norway (SATREF), Finland (FinnRef) and Denmark, totally 49 stations, have been included in the SWEREF 99 solution. From Swepos, data for six GPS-weeks 10141019, (June 13 July 24 1999) were used and from the foreign stations, 23 weeks of data were used (GPS-weeks 10141015, 1019).

  • The SWEREF 99 solution has been computed in ITRF97 epoch 1999.5 and then converted back to ETRS89 in accordance with the EUREF guidelines
  • The epoch for plate tectonics is 1989.0
    The epoch for intraplate deformations is 1999.5
  • The ellipsoid used with SWEREF 99 is GRS 1980

Review of SWEREF 99

Map of the Nordic and Baltic countries, showing the reference stations  of the SWEREF 99 campaign.
Red dots show the defining stations of the SWEREF 99 review. The other stations in the campaign are shown in black.

The SWEREF 99 coordinates of the Swepos stations, that are defining the reference system SWEREF 99, were updated in the beginning of 2021. Since the original SWEREF 99 campaign, the coordinates of the Swepos stations have been updated when necessary, e.g. when antennas are changed and when new antenna models and computation strategies have been introduced. The purpose of the review and coordinate update is to achieve a more homogeneous SWEREF 99 that will be more sustainable for the future. An overall measure has been taken to obtain a reference system that is consistent with today's measurements and computations.

The number of defining stations has increased with the update, to some thirty stations in Sweden and, in addition, approximately 100 stations in our neighbouring countries. The number of foreign defining stations will however decrease with time, since we don't have the ambition to determine all foreign stations anew when they are altered.

The differences between the previous and the updated coordinates are, on the whole, small and lies within the specifications of the Swepos services.

More information

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