A bias-free geodetic boundary value problem approach to height datum unification

Ardalan, Alireza A.; Karimi, Roohollah; Poutanen, Markku

doi:10.1007/s00190-009-0348-8

Cited by 9 publications

(5 citation statements)

References 33 publications

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“…A formal analysis of this approach is given in Rummel and Teunissen (1988) whose work was essentially a more rigorous continuation of earlier studies performed by Colombo (1980) and Hajela (1983); for more details, see also Heck and Rummel (1990). Additional contributions and important theoretical extensions have been made by many authors, including Xu and Rummel (1991), Rapp and Balasubramania (1992), Balasubramania (1994), Sansò and Usai (1995), Lehmann (2000), Sansò and Venuti (2002), Sacerdote and Sansò (2004) and Ardalan et al (2010) among others.…”

mentioning

confidence: 94%

Estimation of the zero-height geopotential level W o LVD in a local vertical datum from inversion of co-located GPS, leveling and geoid heights: a case study in the Hellenic islands

Kotsakis

Katsambalos

Ampatzidis

2011

J Geod

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The estimation of the zero-height geopotential level of a local vertical datum (LVD) is a key task towards the connection of isolated physical height frames and their unification into a common vertical reference system. Such an estimate resolves, in principle, the 'ambiguity' of a traditional crust-fixed LVD by linking it with a particular equipotential surface of Earth's gravity field under the presence of an external geopotential model. The aim of this paper is to study the estimation scheme that can be followed for solving the aforementioned problem based on the joint inversion of co-located GPS and leveling heights in conjunction with a fixed Earth gravity field model. Several case studies with real data are also presented that provide, for the first time, precise estimates of the LVD offsets for a number of Hellenic islands across the Aegean and Ionian Sea.

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mentioning

confidence: 94%

Estimation of the zero-height geopotential level W o LVD in a local vertical datum from inversion of co-located GPS, leveling and geoid heights: a case study in the Hellenic islands

Kotsakis

Katsambalos

Ampatzidis

2011

J Geod

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“…While most estimates of LVD offsets are made using geodetic methods (e.g., Rummel and Teunissen 1988;Catalao and Sevilla 2009;Zhang et al 2009;Amos and Featherstone 2009;Ardalan et al 2010), or (geodetic) SSTop modeled from satellite altimetry-derived mean sea surface (MSS) minus gravimetric geoid models at tide-gauges (e.g., Fenoglio and Groten 1995), this study also uses SSTop values modeled only from oceanographic information (see Data and Methods section), which is rarely used to estimate LVD offsets (cf. Merry and Vaníček 1983).…”

Section: Introductionmentioning

confidence: 99%

A Re-Evaluation of the Offset in the Australian Height Datum Between Mainland Australia and Tasmania

Filmer

Featherstone

2012

Marine Geodesy

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The adoption of local mean sea level (MSL) at multiple tide-gauges as a zero reference level for the Australian Height Datum (AHD) has resulted in a spatially variable offset between the geoid and the AHD. This is caused primarily by sea surface topography (SSTop), which has also resulted in the AHD on the mainland being offset vertically from the AHD on the island of Tasmania. Errors in MSL observations at the 32 tidegauges used in the AHD and the temporal bias caused by MSL observations over different time epochs also contribute to the offset, which previous studies estimate to be between ∼+100 mm and ∼+400 mm (AHD on the mainland above the AHD on Tasmania). This study uses five SSTop models (SSTMs), as well as GNSS and two gravimetric quasigeoid models, at tide-gauges/tide-gauge benchmarks to re-estimate the AHD offset, with the re-evaluated offset between −61 mm and +48 mm. Adopting the more reliable CARS2006 oceanographic-only SSTM, the offset is −12 ± 11 mm, an order of magnitude less than three previous studies that used geodetic data alone. This suggests that oceanographically derived SSTMs should be considered as a viable alternative to geodetic-only techniques when attempting to unify local vertical datums.

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“…Some examples are the works by Safari (2005), Zhang et al (2009) and Ardalan et al (2010). Ardalan and Safari (2005) proposed a method for a global vertical datum unification based on the solution of the fixed-free two-boundary-value problem (Ardalan and Grafarend 2004).…”

Section: Third Strategy: the Geodetic Boundary Value Problem (Gbvp) Amentioning

confidence: 99%

“…Zhang et al (2009) unified the height datums between Shenzhen and Hong Kong using the solution of the linearized fixed GBVP. Ardalan et al (2010) formulated a bias-free GBVP approach for vertical datum unification using potential and gravity differences considered as bias-free observables. Gruber et al (2012) used GOCE-based GGMs to compute relative intercontinental height datum offsets.…”

Section: Third Strategy: the Geodetic Boundary Value Problem (Gbvp) Amentioning

confidence: 99%

The GBVP approach for vertical datum unification: recent results in North America

Amjadiparvar

Rangelova

Sideris

2015

J Geod

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Two levelling-based vertical datums have been used in North America, namely CGVD28 in Canada and NAVD88 in the USA and Mexico. Although the two datums will be replaced by a common and continent-wide vertical datum in a few years, their connection and unification are of great interest to the scientific and user communities. In this paper, the geodetic boundary value problem (GBVP) approach is studied as a rigorous method for connecting two or more vertical datums through computed datum offsets from a global equipotential surface defined by a GOCEbased geoid. The so-called indirect bias term, the effect of the GOCE geoid omission error, the effect of the systematic levelling datum errors and distortions, and the effect of the geodetic data errors on the datum unification are four important factors affecting the practical implementation of this approach. These factors are investigated numerically using the GNSS-levelling and tide gauge stations in Canada, the USA, Alaska, and Mexico. The results show that the indirect bias term can be omitted if a GOCE-based global geopotential model is used in gravimetric geoid computations. The omission of the indirect bias term simplifies the linear system of equations for the estimation of the datum offset(s). Because of the existing systematic levelling errors and distortions in the Canadian and US levelling networks, the datum offsets are investigated in eight smaller regions along the Canadian and US coastal areas. Using GNSSlevelling stations in the US coastal regions, the mean datum offset can be estimated with a 1 cm standard deviation if the GOCE geoid omission error is taken into account by means of the local gravity and topographic information. In the Cana-B B. Amjadiparvar

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A bias-free geodetic boundary value problem approach to height datum unification

Cited by 9 publications

References 33 publications

Estimation of the zero-height geopotential level W o LVD in a local vertical datum from inversion of co-located GPS, leveling and geoid heights: a case study in the Hellenic islands

Estimation of the zero-height geopotential level W o LVD in a local vertical datum from inversion of co-located GPS, leveling and geoid heights: a case study in the Hellenic islands

A Re-Evaluation of the Offset in the Australian Height Datum Between Mainland Australia and Tasmania

The GBVP approach for vertical datum unification: recent results in North America

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