W0 Estimates in the Frame of the GGOS Working Group on Vertical Datum Standardisation

conference paper

English

During the 2011 IUGG General Assembly, GGOS, the IAG Commissions 1 (Reference Frames) and 2 (Gravity Field) and the IGFS established a joint working group devoted to the Vertical Datum Standardisation. This working group supports the activities of GGOS Theme 1 Unified Height System; in particular, to recommend a reliable geopotential value W0 to be introduced as the conventional reference level for the realisation of the GGOS Vertical Reference System. At present, the most commonly accepted W0 value corresponds to the best estimate available in 2004; however, this value presents discrepancies of about 2 m2 s−2 with respect to recent computations based on the latest Earth’s surface and gravity field models. According to this, as a first approach, four different teams working on the computation of a global W 0 value were brought together in order to compare methodologies and models, and to establish the reliability of the individual computations. Results of this comparison show that the four individual estimates present a maximum discrepancy of about 0.5 m2 s−2. They also confirm that the W 0 value declared as the best estimate in 2004 corresponds to an equipotential surface located about 17 cm beneath the sea surface scanned by satellite altimetry, while the potential value U0 of the GRS80 ellipsoid realises an equipotential surface located about 67 cm lower. In this context, the need to provide a new better estimate of W0 is evident.

Vertical datum, unification height system, W0

VATRT, V.

2014

20. 12. 2014

Springer International Publishing

Springer International Publishing Switzerland

978-3-319-10836-0

Gravity, Geoid and Height Systems

1

1

0939-9585

International Association of Geodesy Symposia

141

141

unknown

203

210

8