Minutes of Arctic Gravity Project Working Meeting, Birmingham, July 22, 1999



Participants:

M. Veronneau, M. Sideris (Canada); K. Keller, R. Forsberg (Denmark); D. Solheim (Norway); M. Lidberg, (Sweden); A. Zayonchek, G. Demianov, S. Maschenkov (Russia); L. Holcomb, J. Manning (Australia); M. Vermeer (Finland); J. Kaminskis (Latvia); V. Childers, C. Jekeli, J. Kwon (USA); R. Dietriech, U. Schaefer, M. Loenig, H.-W. Schenke (Germany); M. Sarrailh, J. P. Bariot (France); P. Morris (UK); A. Capra (Italy).

Agenda:

  1. Arctic Gravity Project: Background and status
  2. Individual informal presentations on gravity data sets
  3. Ongoing surveys and future cooperative activities
  4. Time schedule and practical arrangments for making a 5’ public domain grid ready by 2001
  5. Other business

1.

The chairman (R. Forsberg) gave a brief presentation of background of ArcGP, and welcomed participants in meeting, including several participants interested primarily in Antarctica gravity field. Group members were thanked for the effort already done.

2+3.

M. Verennau, GSD/Canada, presented surface gravity status in Canada – Foxe Basin is still a gap, otherwise situation good, full coverage. Airborne gravity activities ongoing in Arctic in PMAP project.

K. Keller, KMS/Denmark, presented status of ongoing KMS airborne gravity work in Greenland, north and northeast shelf areas completed by 1999.

V. Childers, NRL/USA presented background on NRL’s long-range Arctic aerogravity program. 3 mill. sq. km of Arctic completed with NGA support, 2-3 mgal cross-overs.

D. Solheim, SK/Norway presented ongoing aerogravity work 1998-99 to complete gravity coverage of Svalbard and surrounding sea-areas in cooperation with KMS. Also showed proposed survey in Antarctica.

A. Zayonchek, VNIIO/Russia displayed Russian gravity map coverage, and results of compiling a 10 km grid using Russian maps, 4 yrs of NRL data, and Canadian data. Underlying data spacing is roughly 1 pt / 10 km, denser over Russian shelf areas.

G. Demianov, Tsniigaik/Russia, talked about Russian land coverage, 10’ grid data to be made available in cooperation with northern hemisphere geoid project. 30’ data compilation used for GAO global earth models.

M. Sarrailh, BGI/France, discussed BGI’s compilation of gravity over sea-ice from ERS-1. 20 Hz data used, retracked. Filtered to wavelength 40 km.

M. Lidberg, Sweden, showed Swedish gravity coverage. 1 point every 5 km.

H.-W. Schenke, AWI/Germany: Presented on behalf of International Arctic Bathymetric Project (IOC/IHO) status of compilations of depth data. Contribution from US submarine surveys 1958-1983 just released. A preliminary model to be finished fall 99. SCICEX submarine data not included yet. Martin Jakobssen, Sweden, did much of practical compilation. Final chart to be published Oct. 2000.

Rene Forsberg, KMS/Denmark mentioned details of some ongoing activities contributed, a.o. AWI surveys in Arctic, which have been contributed to ArcGP. NGA representative showed coverage of current ArcGP sources contributed.

Discussions were made about eventual Russian gravity data release. Russian data made available in some form would be crucial for the project. Some data have allready been contributed, and Russian delegates were optimistic about future declassifications of mean anomaly data (not detailed point values). The Russian Academy of Sciences to be contacted formally about release of data.

4.

It was agreed to to make the grid in the form of a 5’ grid from 64N to the pole, with grid center shifted 2.5’ in accordance with Canadian grids (that has advantage of not having multiple values at North Pole). A special extension of grid to 62 N would be made to include Iceland.

Final grid would be a free-air grid at sea-level (at level of surface of topography on land). A Bouguer anomaly grid will be derived from bathymetry project DEM. This would also require use of 5’ ice thickness models over glaciers and ice caps. Geoid would be another derived product.

Agreed time schedule calls for collection of data until end of 2000, then compilation of all available data and release of grids by mid-2001. Details of final data compilation methods to be discussed at next ArcGP working meeting. This meeting to be held in St. Petersburg, Russia, early 2000. (Limited) support for travel available through IAG and possibly IASC.

5.

Some brief discussion of a future similar project in Antarctica were held, in order to support especially need of satellite geodesy (filling "polar gaps"). Antarctica geodesy activities in general allready closely coordinated through SCAR (www.scar-ggi.org.au/Geodesy).


Point of Contact: Office of Geomatics
phone (314) 676-9127, DSN 846-9127
wgs84@nga.mil

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