Mapping the geoid for Iberia and the Macaronesian Islands using multi-sensor gravity data and the GRACE geopotential model

Abstract

To cite this version:J. Catalão, M.J. Sevilla. Mapping the geoid for Iberia and the Macaronesian Islands using multisensor gravity data and the GRACE geopotential model. Journal of Geodynamics, Elsevier, 2009, 48 (1) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Iberia, and the Macaronesian Islands using multi-sensor gravity data and a GRACE derived Earth geopotential model. A high resolution gravity model, determined using least squares optimal interpolation of marine, land, and satellite derived gravity anomalies, was used to resolve the medium and short wavelengths of the geoid. Long wavelengths of the geoid were provided by the GRACE derived Earth geopotential model. The topographic effects were computed in the spectral domain using a high resolution (100 m) digital terrain model derived from SRTM mission data and cartographic charts. The remove-restore technique was used to compute the geoid model on a 1.5 arc minute grid, and the residual geoid height was computed using spherical FFT and a modified Stokes' kernel. The effects of different Earth tide models on the geoid were computed and analyzed.Comparison over the sea with an oceanographic geoid determined from CLS01 MSSH and Rio05MDT yield a relative accuracy of 8 cm, with larger differences close to the shoreline. Over land, comparisons with 1646 GPS/levelling marks indicate an overall precision of 8-10 cm and relative vertical datum offsets of up to 2 m. This new geoid model represents a significant improvement over existing geoid models, with a homogeneous relative accuracy of 8-10 cm over both marine and land areas, and exposes the inaccuracies of local vertical datums as references for studies of vertical deformation.

A Comparison Between Three IMUs for Strapdown Airborne Gravimetry

“…Enormous misfits of 15 cm were observed when comparing the new local geoid with GPS/levelling data over the island. Similar values were presented before by Catalão and Sevilla (2009) the problem may come from the GPS/levelling data but that falls outside the scope of the current research to go into the detail. Extracting the gravity signal from iMAR was not straightforward, and a gravity reference was needed to model and remove the nonlinear drift present in the data.…”

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

“…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).…”

Understanding Constraints and Triggering Factors of Landslides: Regional and Local Perspectives on a Drainage Basin

“…Orthometric altitude of each point was determined by correcting the ellipsoidal altitude. The GeodPT08 model [38,39] was used for this purpose, allowing for an altimetric accuracy that was better than 4 cm for three-dimensional (3D) real-time GNSS (Global Navigation Satellite System) users [38].…”