Nordiska Kommissionen för Geodesi  Nordic Geodetic Commission Working Group for Geodynamics

Short meeting at Espoo, Oct 4, 2002

1. Relative gravity profiles, revisiting 63^oN 2003
2. Absolute instruments, scenarios (FGI, Hannover, NLH)
3. Absolute measurements: FGI, BKG. NKGstarting NGGOS/AG-Plan with 63^oN 2003
4. New points: Kramfors, Östersund/Norderåsen GPS station and Vågstranda need concrete platforms.
5. Next meeting (Spring 03)

Participants: Gabriel Strykowski (DK), Jaakko Mäkinen, Hannu Ruotsalainen (FI), Hans-Peter Plag (N), Martin Lidberg, Mikael Lilje, Hans-Georg Scherneck (S)

Hans-Georg Scherneck, chairperson
Martin Lidberg, secretary

Meeting opened

1§  The 63^oN Land Uplift Gravity Line is to be remeasured in 2003 in order to keep the five-year schedule. The campaign is endorsed in the NKG Gen. Ass'y Resolutions 2002. The measurements are usually started in the second half or last week of August. All participating crews must be well trained with respect to the high reliability and precision that the project requires and for which it has devised special routines.
   FGI in Finland and Lantmäteriet in Sweden will be active with crews and instruments. Statens Kartverk in Norway can contribute instruments. KMS in Denmark is willing to participate but has first to survey the current situation.
   FGI collects and archives the data. If previous campaigns are not submitted yet, Jaakko Mäkinen and Hannu Ruotsalainen are looking forward to complementary sendings.

2§  FGI will obtain a new FG5 absolute gravimeter beginning of 2003. The instrument will be used for measurements on the 63^oN line as the first effort to implement the NGGOS/AG-plan (see next point for details).
   The Geodetic Institute at the University of Hannover has applied for a gravity project for GRACE Gound-Truth measuerements that includes an absolute gravimeter (FG5).
   The Institute for Kartography and Mapping at the Agricultural University of Ås (Norway) has a pending application to the Norwegian Research Council that comprises a five-year strategic support for research on gravity and includes a 1/3 share of a joint Nordic FG5 instrument.

3§   FGI has submitted a proposal to the Academy of Finland to obtain financial support for travel costs and absolute gravimeter operations outside Finland. The proposal includes work in Scandinavia. It will be decided upon during November 2002.
   Without extra support FGI needs to equilibrate its mutual services. The cost burdon of the gravimeter operation could be compensated by training of observers and analysts within geodynamic research applications.
  The University of Hannover, if successful with their application to the German DFG, will start their absolute gravity campaigns in 2003.
  BKG has scheduled remeasurements of the Fennoscandian and Svalbard points preliminarily for June and July 2003. The previous campaign was carried out in 1998, and the costs and supplies for the visit (travel and one accompanying oberserver) had kindly been provided by SK. The next campaign needs the support of organisations in the country where the measurements are carried out. The project with BKG aims at a publication as soon as possible after the 2003 campaign.

4§   The AG-Plan suggests that new platforms are needed at Kramfors, Östersund (Norderåsen), and Vågstranda. Jaakko informed about experience with the platform on the Vihti calibration line. A platform does not necessarily need permanent electricity or cover. A generator and a temporary shed or tent can be used. He volunteered to help in reconnaissance and construction. On the Swedish side the Continuous GPS at Norderåsen (OSTE) is close to the 63^o line. A GPS station is desirable but not indispensable at Kramfors and Vågstranda. If we can build the absolute-gravity platforms such that the gravity difference to the old relative stations is small (preferably less than 1 mgal), then we can attach the new absolute-gravity time series directly to the 35-year relative-gravity series.  This advantage compensates for the possible absence of CGPS. A platform suitable for absolute gravimetry exists at the SATREF station of Ålesund. In Finland, the 63^o stations Vaasa and Joensuu are  co-located with absolute-gravity platforms and CGPS.

5§    Next meeting in April 2003 in Copenhagen (thanks, Gabriel!)

Meeting closed.

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