The GGOS as the backbone for global observing and local monitoring: A user driven perspective

Abstract

A key geodetic contribution to both the three Global Observing Systems and initiatives like the European Global Monitoring for Environment and Security is an accurate, long-term stable, and easily accessible reference frame as the backbone. Many emerging scientific as well as non-scientific high-accuracy applications require access to an unique, technique-independent reference frame decontaminated for short-term fluctuations due to global Earth system processes. Such a reference frame can only be maintained and made available through an observing system such as the Global Geodetic Observing System (GGOS), which is currently implemented and expected to provide sufficient information on changes in the Earth figure, its rotation and its gravity field. Based on a number of examples from monitoring of infrastructure, point positioning, maintenance of national references frames to global changes studies, likely future accuracy requirements for a global terrestrial reference frame are set up as function of time scales. Expected accuracy requirements for a large range of high-accuracy applications are less than 5 mm for diurnal and sub-diurnal time scales, 2-3 mm on monthly to seasonal time scales, better than 1 mm/year on decadal to 50 years time scales. Based on these requirements, specifications for a geodetic observing system meeting the accuracy requirements can be derived.

A Review of Higher Order Ionospheric Refraction Effects on Dual Frequency GPS

“…However, geodetic GPS processing is now aiming for rates of movement known to well within 1 mm/year (Plag 2005). There is a wide range of applications, varying from vertical land motion estimates for calibration of tide gauges and comparison with glacial isostatic adjustment (Bouin and Wöppelmann 2010), to tectonic strain (e.g.…”

“…There is a wide range of applications, varying from vertical land motion estimates for calibration of tide gauges and comparison with glacial isostatic adjustment (Bouin and Wöppelmann 2010), to tectonic strain (e.g. Calais et al 2005) and long term subsidence monitoring of oil rigs (Plag 2005). An excellent review of some of the many geodetic applications of GPS can be found in Herring (1999).…”

The Nordic Geodetic Observing System (NGOS)

“…User requirements for monitoring of such infrastructure are of the order of less than 1 cm for sub-daily to daily positions available with a latency of a few days, 2-3 mm on monthly to seasonal time scales, and 1 mm/yr for long-term stability (Plag, 2004).…”