The spherical Slepian basis as a means to obtain spectral consistency between mean sea level and the geoid

Slobbe, Cornelis; Simons, Frederik J.; Klees, R.

doi:10.1007/s00190-012-0543-x

Cited by 31 publications

(17 citation statements)

References 32 publications

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“…A hard truncation of the SRBFs at the maximum degree of the low-resolution dataset is the right choice in global quasi-geoid modelling, but provides a wrong functional model in local quasi-geoid modelling. This is in line with the results in (Slobbe et al 2012). Applying a taper to both the low-resolution dataset and the SRBF model solves this problem.…”

Section: Discussionsupporting

confidence: 88%

A methodology for least-squares local quasi-geoid modelling using a noisy satellite-only gravity field model

Klees

Slobbe

Farahani

2017

J Geod

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The paper is about a methodology to combine a noisy satellite-only global gravity field model (GGM) with other noisy datasets to estimate a local quasi-geoid model using weighted least-squares techniques. In this way, we attempt to improve the quality of the estimated quasi-geoid model and to complement it with a full noise covariance matrix for quality control and further data processing. The methodology goes beyond the classical remove-computerestore approach, which does not account for the noise in the satellite-only GGM. We suggest and analyse three different approaches of data combination. Two of them are based on a local single-scale spherical radial basis function (SRBF) model of the disturbing potential, and one is based on a two-scale SRBF model. Using numerical experiments, we show that a single-scale SRBF model does not fully exploit the information in the satellite-only GGM. We explain this by a lack of flexibility of a single-scale SRBF model to deal with datasets of significantly different bandwidths. The two-scale SRBF model performs well in this respect, provided that the model coefficients representing the two scales are estimated separately. The corresponding methodology is developed in this paper. Using the statistics of the least-squares residuals and the statistics of the errors in the estimated two-scale quasi-geoid model, we demonstrate that the developed methodology provides a two-scale quasigeoid model, which exploits the information in all datasets.

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Section: Discussionsupporting

confidence: 88%

A methodology for least-squares local quasi-geoid modelling using a noisy satellite-only gravity field model

Klees

Slobbe

Farahani

2017

J Geod

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“…We transformed the geopotential fields into surface mass density by removing the gravitational effect of instantaneous elastic deformation arising from current mass change (le Meur and Huybrechts, 1996), in a Love number loading formalism (Wahr et al, 1998). We did not correct for the bias of migrating water that accompanies changes in ice mass (Sterenborg et al, 2013), nor did we account for the influence of recent sea level rise trends in the Southern Ocean (Rye et al, 2014) on our estimation. Global surface mass density fields were projected into a Slepian basis specifically designed for the regions of interest, such as all of Antarctica, its regions West Antarctica, the Peninsula, Dronning Maud and Wilkes Lands, and so on.…”

Section: Data and Modelsmentioning

confidence: 99%

Accelerated West Antarctic ice mass loss continues to outpace East Antarctic gains

Harig

Simons

2015

Earth and Planetary Science Letters

104

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“…Several sophisticated approaches to optimal filtering of an altimetric MDT have recently been developed (e.g. Bingham et al 2011;Knudsen et al 2011;Slobbe et al 2012;Becker et al 2014), each of which has pointed to the deficiencies of simple low-pass spatial filtering of the MDT field to reduce noise. However, in the present case we believe that such a simple approach is adequate in describing the MDT's main features.…”

Section: Mdt From Altimetry Minus Geoidmentioning

confidence: 99%

The status of measurement of the Mediterranean mean dynamic topography by geodetic techniques

Woodworth

Gravelle

Marcos

et al. 2015

J Geod

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We review the measurement of the mean dynamic topography (MDT) of the Mediterranean using ellipsoidal heights of sea level at discrete tide gauge locations, and across the entire basin using satellite altimetry, subtracting estimates of the geoid obtained from recent models. This 'geodetic approach' to the determination of the MDT can be compared to the independent 'ocean approach' that involves the use of in situ oceanographic measurements and ocean modelling. We demonstrate that with modern geoid and ocean models there is an encouraging level of consistency between the two sets of MDTs. In addition, we show how important geodetic MDT information can be in judging between existing global ocean circulation models, and in providing insight for the development of new ones. The review makes clear the major limitations in Mediterranean data sets that prevent a more complete validation, including the need for improved geoid models of high spatial resolution and accuracy. Suggestions are made on how a greater amount of reliable geo-located tide gauge information can be obtained in the future. IntroductionThis paper discusses the mean dynamic topography (MDT) of the Mediterranean and its measurement by geodetic techniques. The MDT is the amount by which the Mean Sea Surface (MSS) is further from the centre of the Earth than a surface called the geoid, which is an equipotential surface resulting from the Earth's spatially-varying gravity field, and which would correspond to the MSS in the absence of an ocean circulation. An accurate measurement of the MDT can, therefore, provide oceanographers with insight into the circulation. Conversely, knowledge of the circulation, obtained by a number of oceanographic techniques can be used to infer the MDT. 2Much is already known about the mean circulation of the Mediterranean and its variability (e.g. Pinardi and Masetti 2000) and, therefore, also about the spatial variation of its MDT. This insight has largely been obtained using in situ oceanographic measurements and ocean modelling. However, in recent years major advances have been made in geodetic techniques that have enabled the MDT to be determined, for the first time, as the difference between MSS and geoid to the accuracy required for oceanographic research (e.g. Bingham et al. 2014). These techniques have primarily involved satellite altimetry to provide the MSS over the open ocean and space gravity to provide the geoid, complemented at the coast with the use of tide gauges equipped with Global Positioning System (GPS) equipment (Woodworth et al. 2012). By studying the Mediterranean, particular lessons can be learned in the use of these techniques, notably by pointing to missing infrastructure and data limitations, which can also be relevant to discussion of the MDT in other data-sparse regions around the world.Models of the MDT in the Mediterranean have already been made by previous authors in various ways (e.g. Rio et al. 2014a). Consequently, the present paper focuses on reviewing how an MDT model can be compa...

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The spherical Slepian basis as a means to obtain spectral consistency between mean sea level and the geoid

Cited by 31 publications

References 32 publications

A methodology for least-squares local quasi-geoid modelling using a noisy satellite-only gravity field model

A methodology for least-squares local quasi-geoid modelling using a noisy satellite-only gravity field model

Accelerated West Antarctic ice mass loss continues to outpace East Antarctic gains

The status of measurement of the Mediterranean mean dynamic topography by geodetic techniques

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