GGP (Global Geodynamics Project): An International Network of Superconducting Gravimeters to Study Time-Variable Gravity
The Global Geodynamics Project (GGP) is an international network of superconducting gravimeters (SG) first established in 1997 and further extended in 2003. It was decided during the last IUGG assembly in 2007 to move to a permanent network hosted by IAG
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GGP (Global Geodynamics Project): An International Network of Superconducting Gravimeters to Study Time-Variable Gravity D. Crossley and J. Hinderer
Abstract The Global Geodynamics Project (GGP) is an international network of superconducting gravimeters (SG) first established in 1997 and further extended in 2003. It was decided during the last IUGG assembly in 2007 to move to a permanent network hosted by IAG and become part of GGOS. Several new locations are being planned to extend the network to about 30 stations in 2008/2009. One of the present tasks within GGP is to prepare raw GGP data (at sampling times of 1–5 s) for inclusion into the IRIS data set for the seismologists to include in normal mode studies of the Earth. Of continuing interest within GGP is the issue of combining measurements from absolute gravimeters and permanent GPS at the SG stations for a variety of long-term studies of the gravity field such as tectonic uplift, subduction zone slip, post-glacial rebound and present-day ice melting. One of the most interesting new ideas within GGOS is the determination of the geocenter using a combination of satellite and groundbased gravimetry. The GGP network can provide a unique contribution in this respect through continuous data at the stations where absolute gravimeters (AG) will be deployed. The continuous monitoring of timevariable gravity is a tool to investigate many aspects of global Earth dynamics and to contribute to other sciences such as seismology, oceanography, earth rotation, hydrology, volcanology, and tectonics. Another promising application is the use of SG sub-networks in Europe and Asia to validate time-varying satellite gravity observations (GRACE, GOCE) due to continental hydrology and large-scale seismic deformation. D. Crossley () Department of Earth and Atmospheric Sciences, Saint Louis University, St. Louis, MO 63108, USA e-mail: [email protected]
83.1 GGP Stations This paper is in part a review of the GGP superconducting gravimeter (SG) network, for the benefit of those who may not be familiar with ground-based timevariable gravity observations. Later, we emphasize the connection between GGP and some of the goals of the GGOS program. We begin, as usual, with a map of stations (Fig. 83.1) that shows the distribution of the 25 or so currently recording SG stations, together with the locations of some older stations and others planned for the near future. Note that the original designation Dehradun (India) has been changed to the actual site, Ghuttu. The SG is a complex instrument requiring specific site properties, and, in common with other comparable technologies, there is a cluster of sites in Europe and Asia, and elsewhere the distribution is more widely scattered. It is noteworthy that scientists in Germany and Japan have made efforts to locate instruments in some of the more remote sites. For example Syowa (Antarctic), Ny-Alesund (Norway), Canberra (Australia), and Bandung (Indonesia) were established by the Japanese, and Sutherland (S. Africa), Concepcion (Chile), and
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