Impact of accounting for coloured noise in radar altimetry data on a regional quasi-geoid model

Impact of accounting for coloured noise in radar altimetry data on a regional quasi-geoid model

Farahani, H. (TU Delft Novel Aerospace Materials)
Slobbe, D.C. (TU Delft Physical and Space Geodesy)
Klees, R. (TU Delft Physical and Space Geodesy)
Seitz, Kurt (Karlsruhe Institut für Technologie)

2017-01-01

We study the impact of an accurate computation and incorporation of coloured noise in radar altimeter data when computing a regional quasi-geoid model using least-squares techniques. Our test area comprises the Southern North Sea including the Netherlands, Belgium, and parts of France, Germany, and the UK. We perform the study by modelling the disturbing potential with spherical radial base functions. To that end, we use the traditional remove-compute-restore procedure with a recent GRACE/GOCE static gravity field model. Apart from radar altimeter data, we use terrestrial, airborne, and shipboard gravity data. Radar altimeter sea surface heights are corrected for the instantaneous dynamic topography and used in the form of along-track quasi-geoid height differences. Noise in these data are estimated using repeat-track and post-fit residual analysis techniques and then modelled as an auto regressive moving average process. Quasi-geoid models are computed with and without taking the modelled coloured noise into account. The difference between them is used as a measure of the impact of coloured noise in radar altimeter along-track quasi-geoid height differences on the estimated quasi-geoid model. The impact strongly depends on the availability of shipboard gravity data. If no such data are available, the impact may attain values exceeding 10 centimetres in particular areas. In case shipboard gravity data are used, the impact is reduced, though it still attains values of several centimetres. We use geometric quasi-geoid heights from GPS/levelling data at height markers as control data to analyse the quality of the quasi-geoid models. The quasi-geoid model computed using a model of the coloured noise in radar altimeter along-track quasi-geoid height differences shows in some areas a significant improvement over a model that assumes white noise in these data. However, the interpretation in other areas remains a challenge due to the limited quality of the control data.

ARMA
Coloured noise
Quasi-geoid
Radar altimetry
Spherical radial base functions

http://resolver.tudelft.nl/uuid:c00bcb60-af81-4740-b73d-7cb40bd29b60

https://doi.org/10.1007/s00190-016-0941-6

0949-7714

Journal of Geodesy, 91 (1), 97-112

Institutional Repository

journal article

© 2017 H. Farahani, D.C. Slobbe, R. Klees, Kurt Seitz