scholarly journals The Unique Role of the Jason Geodetic Missions for high Resolution Gravity Field and Mean Sea Surface Modelling

2021 ◽  
Vol 13 (4) ◽  
pp. 646
Author(s):  
Ole Baltazar Andersen ◽  
Shengjun Zhang ◽  
David T. Sandwell ◽  
Gérald Dibarboure ◽  
Walter H. F. Smith ◽  
...  
Keyword(s):  
High Resolution ◽  
Gravity Field ◽  
Orbital Plane ◽  
Sea Surface ◽  
Gravity Models ◽  
Life Phase ◽  
Mean Sea Surface ◽  
Successful Launch ◽  
Gravity Recovery ◽  
First Time

The resolutions of current global altimetric gravity models and mean sea surface models are around 12 km wavelength resolving 6 km features, and for many years it has been difficult to improve the resolution further in a systematic way. For both Jason 1 and 2, a Geodetic Mission (GM) has been carried out as a part of the Extension-of-Life phase. The GM for Jason-1 lasted 406 days. The GM for Jason-2 was planned to provide ground-tracks with a systematic spacing of 4 km after 2 years and potentially 2 km after 4 years. Unfortunately, the satellite ceased operation in October 2019 after 2 years of Geodetic Mission but still provided a fantastic dataset for high resolution gravity recovery. We highlight the improvement to the gravity field which has been derived from the 2 years GM. When an Extension-of-Life phase is conducted, the satellite instruments will be old. Particularly Jason-2 suffered from several safe-holds and instrument outages during the GM. This leads to systematic gaps in the data-coverage and degrades the quality of the derived gravity field. For the first time, the Jason-2 GM was “rewound” to mitigate the effect of the outages, and we evaluate the effect of “mission rewind” on gravity. With the recent successful launch of Sentinel-6 Michael Freilich (S6-MF, formerly Jason CS), we investigate the possibility creating an altimetric dataset with 2 km track spacing as this would lead to fundamental increase in the spatial resolution of global altimetric gravity fields. We investigate the effect of bisecting the ground-tracks of existing GM to create a mesh with twice the resolution rather than starting all over with a new GM. The idea explores the unique opportunity to inject Jason-3 GM into the same orbital plane as used for Jason-2 GM but bisecting the existing Jason-2 tracks. This way, the already 2-years Jason-2 GM could be used to create a 2 km grid after only 2 years of Jason-3 GM, rather than starting all over with a new GM for Jason-3.

High‐resolution, high‐accuracy altimeter derived mean sea surface in the Norwegian Sea

1990 ◽  
Vol 14 (1) ◽  
pp. 57-76 ◽  
Author(s):  
Frédérique Blanc ◽  
Sabine Houry ◽  
Pierre Mazzega ◽  
Jean François Minster
Keyword(s):  
High Resolution ◽  
High Accuracy ◽  
Sea Surface ◽  
Norwegian Sea ◽  
Mean Sea Surface

scholarly journals A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters

2020 ◽  
Author(s):  
Hadi Amin ◽  
Lars E. Sjöberg ◽  
Mohammad Bagherbandi
Keyword(s):  
Gravity Field ◽  
Satellite Altimetry ◽  
Input Data ◽  
Equipotential Surface ◽  
Sea Surface ◽  
Dynamic Topography ◽  
The Earth ◽  
Degree Harmonic ◽  
Mean Sea Surface ◽  
Zero Degree

<p>According to the classical Gauss–Listing definition, the geoid is the equipotential surface of the Earth’s gravity field that in a least-squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s Global Gravity Models (GGM). Although nowadays, the satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the Mean Earth Ellipsoid (MEE). In this study, we perform joint estimation of W<sub>0</sub>, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface, and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W<sub>0</sub>. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e. mean sea surface and mean dynamic topography models. Moreover, as W<sub>0</sub> should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea-level changes on the estimation of W<sub>0</sub>. Our computations resulted in the geoid potential W<sub>0 </sub>= 62636848.102 ± 0.004 m<sup>2</sup>s<sup>-2</sup> and the semi-major and –minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of the GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 10<sup>6</sup> m<sup>3</sup>s<sup>-2</sup>.</p>

High-resolution numerical modelling of the altimetry-derived gravity disturbances and disturbing gradients

2020 ◽  
Author(s):  
Róbert Čunderlík ◽  
Marek Macák ◽  
Michal Kollár ◽  
Karol Mikula
Keyword(s):  
High Resolution ◽  
Numerical Solution ◽  
Finite Volume ◽  
Sea Surface ◽  
Computational Domain ◽  
Disturbing Potential ◽  
Gravity Disturbances ◽  
Mean Sea Surface ◽  
Upper Boundary ◽  
Goce Satellite

<p>Recent high-resolution mean sea surface models obtained from satellite altimetry in a combination with the GRACE/GOCE-based global geopotential models provide valuable information for detailed modelling of the altimetry-derived gravity data. Our approach is based on a numerical solution of the altimetry-gravimetry boundary-value problem using the finite volume method (FVM). FVM discretizes the 3D computational domain between an ellipsoidal approximation of the Earth's surface and an upper boundary chosen at a mean altitude of the GOCE satellite orbits. A parallel implementation of the finite volume numerical scheme and large-scale parallel computations on clusters with distributed memory allow to get a high-resolution numerical solution in the whole 3D computational domain. Our numerical experiment presents the altimetry-derived gravity disturbances and disturbing gradients determined with the high-resolution 1 x 1 arc min at two altitude levels; on the reference ellipsoid and at the altitude of 10 km above the ellipsoid. As input data, the Dirichlet boundary conditions over oceans/seas are considered in the form of the disturbing potential. It is obtained from the geopotential evaluated on the DTU18 mean sea surface model from the GO_CONS_GCF_2_TIM_R5 geopotential model and then filtered using the nonlinear diffusion filtering. On the upper boundary, the FVM solution is fixed to the disturbing potential generated from the GO_CONS_GCF_2_DIR_R5 model while exploiting information from the GRACE and GOCE satellite missions.</p>

scholarly journals High-resolution mean sea surface computed with altimeter data of Ers-1 (geodetic mission) and topex-poseidon

1996 ◽  
Vol 125 (3) ◽  
pp. 696-704 ◽  
Author(s):  
A. Cazenave ◽  
P. Schaeffer ◽  
M. Berge ◽  
C. Brossier ◽  
K. Dominh ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Surface ◽  
Altimeter Data ◽  
Mean Sea Surface

scholarly journals GRACE application for geological and geographical problems

2017 ◽  
pp. 3-7
Author(s):  
N. S. Tkachenko ◽  
I. V. Lygin
Keyword(s):  
High Resolution ◽  
Literature Review ◽  
Gravity Field ◽  
Satellite Mission ◽  
Earth’S Gravity Field ◽  
Precise Mapping ◽  
Grace Satellite ◽  
Gravity Recovery

In this article we provide the literature review of the geological and geographical problems which were successfully solved due to application of GRACE satellite mission data. GRACE (Gravity Recovery And Climate Experiment) is gravitational satellite mission the purpose of which is precise mapping of variations of Earth’s gravity field. The data has high resolution that gives the opportunity to solve a lot of geological and geographical problems.

Improved mean sea surface estimation by gravity field error covariance weighting

1990 ◽  
Vol 14 (2) ◽  
pp. 101-120 ◽  
Author(s):  
George W. Rosborough ◽  
Thomas M. Kelecy
Keyword(s):  
Gravity Field ◽  
Sea Surface ◽  
Error Covariance ◽  
Surface Estimation ◽  
Mean Sea Surface

scholarly journals A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters

2019 ◽  
Vol 93 (10) ◽  
pp. 1943-1961
Author(s):  
Hadi Amin ◽  
Lars E. Sjöberg ◽  
Mohammad Bagherbandi
Keyword(s):  
Gravity Field ◽  
Satellite Altimetry ◽  
Input Data ◽  
Equipotential Surface ◽  
Sea Surface ◽  
Dynamic Topography ◽  
Earth’S Gravity Field ◽  
Degree Harmonic ◽  
Mean Sea Surface ◽  
Zero Degree

Abstract The geoid, according to the classical Gauss–Listing definition, is, among infinite equipotential surfaces of the Earth’s gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2 s−2 and the semi-major and minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3 s−2.

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