G. Moreaux

Collecte Localisation Satellites | CLS · Geodesy and Orbitography

For the realization of the 2020 International Terrestrial Reference Frame (ITRF2020), the International DORIS Service delivered to the International Earth Rotation and Reference Systems Service (IERS) a set of 1456 weekly solution files from 1993.0 to 2021.0 including station coordinates and Earth orientation parameters (EOPs). The data come from f...

To support precise orbit determination of the altimetry missions, the International DORIS Service (IDS) regularly estimates the DPOD (DORIS terrestrial reference frame for Precise Orbit Determination) solution which includes mean positions and velocities of all the DORIS stations. This solution is aligned to the current realization of the Internati...

This research focuses on the investigation of the deterministic and stochastic parts of the DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) weekly time series aligned to the newest release of ITRF2014. A set of 90 stations was divided into three groups depending on when the data was collected at an individual station: from...

This paper focuses on the investigation of the deterministic and stochastic parts of the DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) weekly time series aligned to the newest release of ITRF2014. A set of 90 stations was divided into three groups depending on when the data was collected at an individual station. To reli...

This research focuses on the investigation of the deterministic and stochastic parts of the DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) weekly coordinate time series from the IDS contribution to the ITRF2014A set of 90 stations was divided into three groups depending on when the data was collected at an individual stat...

In the context of the 2014 realization of the International Terrestrial Reference Frame (ITRF2014), the International DORIS Service (IDS) has delivered to the IERS a set of 1140 weekly SINEX files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 2015.0. From this set of weekly SINEX files, the...

In a geodetic radio frequency observing system the phase center offsets and phase center variations of ground antennae are a fundamental component of mathematical models of the system observables. In this paper we describe work aimed at improving the DORIS Starec ground antenna phase center definition model. Seven antennas were analyzed in the Comp...

The International DORIS Service (IDS) submitted input data for the most recent realization of the International Terrestrial Reference System (ITRS), the International Terrestrial Reference Frame 2014 (ITRF2014). As one of the ITRS Combination Centers, DGFI-TUM is in charge to analyze and assess the quality of the submitted data and to compute a com...

In preparation of the 2014 realization of the International Terrestrial Reference Frame (ITRF2014), the International DORIS Service delivered to the International Earth Rotation and Reference Systems Service a set of 1140 weekly solution files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 20...

The International DORIS Service (IDS) was created in 2003 under the umbrella of the International Association of Geodesy (IAG) to foster scientific research related to the French DORIS tracking system and to deliver scientific products, mostly related to the International Earth rotation and Reference systems Service (IERS). We first present some ge...

While accuracy of tracking station coordinates is of key importance for Precise Orbit Determination (POD) for altimeter satellites, reliability and operationality are also of great concern. In particular, while recent ITRF realizations should be the most accurate at the time of their computation, they cannot be directly used by the POD groups for o...

Analysis of DORIS stations positions time series from IDS combined solution over time period 2000-2012 has revealed discontinuities linked not with geophysical phenomenon, but correlated with beacons frequency shifts. This result was the consequence of assuming the nominal frequency in the measurement model, and not accounting for beacon frequency...

For the preparation of ITRF2008, the IDS processed data from 1993 to 2008, including data from TOPEX/Poseidon, the SPOT satellites and Envisat in the weekly solutions. Since the development of ITRF2008, the IDS has been engaged in a number of efforts to try and improve the reference frame solutions. These efforts include (i) assessing the contribut...

World Gravity Map (WGM) denotes a set of 3 global anomaly maps of the Earth’s gravity field realized by the Bureau Gravimétrique International (BGI), a service of the International Association of Geodesy (IAG). These new products, realized for the Commission for the Geological Map of the World (CGMW), UNESCO, International Union of Geodesy and Geop...

For the preparation of ITRF2008, the IDS processed data from 1993 to 2008, including data from TOPEX/Poseidon, the SPOT satellites and Envisat in the weekly solutions. Since the development of ITRF2008, the IDS has been engaged in a number of efforts to try and improve the reference frame solutions. These efforts include assessing the contribution...

For the development of ITRF2008, the International DORIS Service (IDS) for the first time developed a combination based on the contributions of seven analysis centers using five separate software packages. Data from 1993 to 2009 were processed in weekly batches using the latest geodetic processing standards, mostly consistent with the IERS standard...

The WGM project is a gravity mapping project undertaken under the aegis of the Commission for the Geological Map of the World (CGMW) to complement a set of global geological and geophysical digital maps published and updated by CGMW, such as the World Digital Magnetic Anomaly Map (WDMAM), released in 2007. This new global digital map aims to provid...

The study presented here aims to assess the capabilities and the limits of the use of the GOCE geoid to improve the shelf and coastal ocean low frequency circulations. The approach consists in using advanced data assimilation techniques (namely, the Ensemble Kalman Filter analysis kernel from the SEQUOIA-BELUGA data assimilation platform – De Mey,...

The Least-squares collocation (LSC) method is commonly used in geodesy, but generally associated with globally supported covariance functions, i.e. with dense covariance matrices. We consider locally supported radial covariance functions, which yield sparse covariance matrices. Having many zero entries in the covariance matrice can both greatly red...

SPECTRE (Service and Products for ionospheric Electron Content over Europe) is a result of a 4 years joint effort of IPGP research institution and Noveltis Company. Database Technologies have been developped for providing final ionospheric products and data extraction tools from a dense GPS network. This operationnal service is freely available to...

During the Demeter mission, a continuous global positioning system (GPS) ionospheric tomography above Europe, Japan and California will be performed with the Service and Products of ionosphere Electronic Content and Tropospheric Refractive index over Europe (SPECTRE) experiment. The main goal of the conducted observations is to detect and character...

The dense GPS networks developed for geodesic applications appear to be very efficient ionospheric sensors because of interaction between plasma and electromagnetic waves. Indeed, the dual frequency receivers provide data from which the Slant Total Electron Content (STEC) can be easily extracted to compute Vertical Total Electron Content (VTEC) map...

We show that the ionosphere, as monitored by the dual frequency altimeter of the Jason-1 and Topex satellites, is strongly perturbed above the tsunami wave front generated by the Sumatra earthquake of December 26th, 2004. This perturbation is observed by both Topex and Jason-1, between 2h55 and 3h05 TU and leads to instabilities in the TEC estimate...

The GOCE (Global Ocean Circulation Explorer) satellite mission, scheduled for launch in 2005, is designed to map out the Earth's gravity field to high accuracy on a global scale over a nominal lifetime of 2 years. Changes in the gravity field are caused by the redistribution of mass within the Earth and on or above its surface. Since GOCE will fly...

When harmonic spherical splines are used to interpolate and predict discretely given data we are confronted with the problem of solving symmetric positive definite systems involving as many equations as the number of data. Due to harmonicity, these systems are dense and thus iterative methods should be preferred to direct ones for large data sets....

Detailed scientific data processing using the space-wise approach. Summary The space-wise approach may be implemented using an integration approach or an optimal estimation approach, Least Squares Collocation (LSC). The latter method can at present only be used on limited data sets, such as data with in limited region, or on data which has been ass...

The software elements able to produce GOCE products using either Least Squares Collocation (LSC) or the Integration approach are described. The software should be made available using a distribution system and the quality standards developed in the EU project MANICORAL. A number of problems remain unsolved, and require further investigations and so...

When harmonic spherical splines are used to interpolate and predict discretely given data we are confronted with the problem of solving symmetric positive-definite systems involving as many equations as the number of data Due to harmonicity, these systems are full and thus iterative methods like the conjugate gradient method should be prefered to d...

Three methods to construct positive definite functions with compact support for the approximation of general geophysical harmonic covariance functions are presented. The theoretical background is given and simulations carried out, for three types of covariance functions associated with the determination of the anomalous gravity potential from gravi...

The spline interpolation technique is applied to estimate locally the radial component of a planetary gravity field from residual acceleration data along a special direction, the direction of observation from the Earth. After the presentation of the theoretical framework, the method is tested on synthetic and real data in the case of Venus. It is s...