On the incorporation of sea surface topography in establishing vertical control
One of the major sources of distortion in vertical control networks is caused by neglecting sea surface topography (SST) at tide gauge stations. Often, the orthometric height is fixed to zero at these stations without applying proper corrections for the deviation of the mean sea surface from the equipotential surface represented by the geoid. In view of the significant improvements in SST determination made in the past decade (particularly the low-to-medium frequencies) and the expected improvement in global gravity field models in the near future, it is appropriate to consider practical methods for the incorporation of SST into establishing vertical control. The purpose of this paper is to develop a consistent procedure for incorporating the mean SST values into the combined height network adjustment of terrestrial GPS-on-benchmark data and GPS-on-tide gauge data typically located in coastal areas, harbours, estuaries and/or river mouths. Two main issues that arise for the proper incorporation of SST information into the optimal heterogeneous height network adjustment include (i) the modelling of systematic errors and datum discrepancies among the height data types (ellipsoidal, orthometric, geoid and SST) using a corrector surface and (ii) the separation of random errors for estimating variance components for each height type. The limiting factor in all of these studies is data availability or rather lack of quality data and obtaining reliable initial covariance matrices for the height data in a particular region. However, in lieu of the increased need for cm-level accurate vertical control it is expected that this situation will be significantly improved in the near future.
KeywordsGlobal Navigation Satellite System Global Navigation Satellite System Tide Gauge Satellite Altimetry Geoid Height
Unable to display preview. Download preview PDF.
- Fotopoulos G. (2003) An analysis on the optimal combination of geoid, orthometric and ellipsoidal height data. Ph.D. Thesis, University of Calgary, Department of Geomatics Engineering Report Number 20185.Google Scholar
- Gruber T. and Steigenberger P. (2002) Impact of new gravity field missions for sea surface topography determination. Proceedings of the 3rd Meeting of the International Gravity and Geoid Commission, Tziavos (Ed.), Thessaloniki, Greece, Aug. 26–30, pp. 320–325.Google Scholar
- Heck B. and Rummel R. (1990) Strategies for solving the vertical datum problem using terrestrial and satellite geodetic data. LAG Symposia, vol. 104, Sünkel H and Baker T (Eds.), Springer-Verlag, pp. 116–128.Google Scholar
- Heiskanen W.A. and Moritz H. (1967) Physical Geodesy. W.H. Freeman and Company San Francisco.Google Scholar
- Kearsley A.H.W. (2004) Unification of vertical datums. Report on IAG Commission X Working Group 3 on the Worldwide Unification of Vertical Datums 1999 to 2003, UNSW, Sydney, Australia.Google Scholar
- Kuo C.Y., Shum C.K., Braun A. and Mitrovica J.X. (2004) Vertical crustal motion determined by satellite altimetry and tide gauge data in Fennoscandia, Geophys. Res. Lett., 31, L01608, doi:10.1029/2003GL019106.Google Scholar
- Lemoine F.G., et al. (1998) The development of the joint NASA GSFC and the National Imagery and Mapping Agency (NIMA) geopotential model EGM96. NASA Technical Publication-1998-206861, July 1998.Google Scholar
- Levitus S. (1982) Climatological Atlas of the World Ocean. NOAA/ERL GFDL Professional Paper 13, Princeton, N.J., 173 pp.Google Scholar