The International DORIS Service (IDS) - Recent Developments in Preparation for ITRF2013

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 general background related to the DORIS system (current and planned satellites, current tracking network and expected evolution) and to the general IDS organization (from Data Centers, Analysis Centers and Combination Center). Then, we discuss some of the steps recently taken to prepare the IDS submission to ITRF2013 (combined weekly time series based on individual solutions from several Analysis Centers). In particular, recent results obtained from the Analysis Centers and the Combination Center show that improvements can still be made when updating physical models of some DORIS satellites, such as Envisat, Cryosat-2 or Jason-2. The DORIS contribution to ITRF2013 should also benefit from the larger number of ground observations collected by the last generation of DGXX receivers (first instrument being onboard Jason-2 satellite). In particular for polar motion, sub-millarcsecond accuracy seems now to be achievable. Weekly station positioning internal consistency also seems to be improved with a larger DORIS constellation

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Altimetry for the future: building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Tectonic motion vizualisation through a Virtual Observatory, from space geodesy techniques.

International audienceThis paper presents the astronomical so-called Virtual Observatory (VO), and gives some examples of Webservices hosted by GRGS Analysis Center webpages, that can be used for Earth sciences applications, and for stations operations. GRGS, Groupe de Recherche de Géodésie Spatiale, France, routinely delivers geodetic products to most of the space geodetic services of the International Association of Geodesy. Some of these products are now natively archived following the data format recommended by IVOA, the VO-Table format, an improved version of the XML format. In this paper, we pay a particular attention on the capabilities suitable to extract and use time series of (i) Space Station Coordinates deduced from SLR, DORIS and GPS data, (ii) EOP deduced from SLR and VLBI data. We show how to use all these on-line tools through the web to: select charts to plot, display and edit the data (scale, appearance) ; download data, plots and graph statistics in several formats. The examples will be based on some stations of interest with coordinates (latitudes, longitudes, altitudes) affected by several features such as earthquakes or technological evolutions

DORIS applications for solid earth and atmospheric sciences Applications DORIS aux sciences de la Terre solide et aux sciences de l'atmosphère

International audienceDORIS is a French precise orbit determination system. However, in the past four years, through the creation of the International DORIS Service, a larger international cooperation was involved. Furthermore, the precision of its scientific applications (geodesy, geophysics) gradually improved and expanded to new fields (atmospheric sciences), leading, for example, to the publication of a special issue of the Journal of Geodesy. The goal of this manuscript is to present and explain these changes and to put them in perspective with current results obtained with other space geodetic techniques, such as GPS or Satellite Laser Ranging

Tectonic motion vizualisation through a Virtual Observatory, from space geodesy techniques.

International audienceThis paper presents the astronomical so-called Virtual Observatory (VO), and gives some examples of Webservices hosted by GRGS Analysis Center webpages, that can be used for Earth sciences applications, and for stations operations. GRGS, Groupe de Recherche de Géodésie Spatiale, France, routinely delivers geodetic products to most of the space geodetic services of the International Association of Geodesy. Some of these products are now natively archived following the data format recommended by IVOA, the VO-Table format, an improved version of the XML format. In this paper, we pay a particular attention on the capabilities suitable to extract and use time series of (i) Space Station Coordinates deduced from SLR, DORIS and GPS data, (ii) EOP deduced from SLR and VLBI data. We show how to use all these on-line tools through the web to: select charts to plot, display and edit the data (scale, appearance) ; download data, plots and graph statistics in several formats. The examples will be based on some stations of interest with coordinates (latitudes, longitudes, altitudes) affected by several features such as earthquakes or technological evolutions

Tectonic motion vizualisation through a Virtual Observatory, from space geodesy techniques.

International audienceThis paper presents the astronomical so-called Virtual Observatory (VO), and gives some examples of Webservices hosted by GRGS Analysis Center webpages, that can be used for Earth sciences applications, and for stations operations. GRGS, Groupe de Recherche de Géodésie Spatiale, France, routinely delivers geodetic products to most of the space geodetic services of the International Association of Geodesy. Some of these products are now natively archived following the data format recommended by IVOA, the VO-Table format, an improved version of the XML format. In this paper, we pay a particular attention on the capabilities suitable to extract and use time series of (i) Space Station Coordinates deduced from SLR, DORIS and GPS data, (ii) EOP deduced from SLR and VLBI data. We show how to use all these on-line tools through the web to: select charts to plot, display and edit the data (scale, appearance) ; download data, plots and graph statistics in several formats. The examples will be based on some stations of interest with coordinates (latitudes, longitudes, altitudes) affected by several features such as earthquakes or technological evolutions

Toward a direct combination of space-geodetic techniques at the measurement level: Methodology and main issues

International audienceIn the framework of the activities of the Combination Research Centers (CRC) of the International Earth Rotation and Reference Systems Service (IERS), the French Groupe de Recherche en Géodésie Spatiale (GRGS) studies the benefit of combining space-geodetic techniques (Doppler orbitography and radiopositioning integrated by satellite, GPS, satellite laser ranging, and very long baseline interferometry) at the observational level. This combination aims to produce a global and consistent solution for Earth orientation parameters (EOPs), polar motion xp and yp, and universal time UT1 with a 1-day or a 6-hour sampling, as well as weekly station positions. In this paper we present a methodology for multitechnique combination at the observational level. We process the measurements of the four techniques over a 1-year period (the year 2002) in order to illustrate and validate our method. All techniques are processed with the same computational framework, thus with the same models and a priori values for parameters. By using the same software and conventions, we avoid inconsistencies in individual computations. We process each technique individually and inside the combination. The comparison between these solutions is a way of analyzing the power of our method even if the actual status of our software does not reproduce the state-of-the-art analyses of each technique. However, we produce an analysis of the quality of our individual computations so that readers can get an informed appreciation of the current capabilities of our software. Finally, we present the capability of such combinations in terms of accuracy and precision, we underline the main issues of our method and propose solutions to solve them in the future

Time series visualization tools through a Virtual Observatory in geodesy

International audienceThis poster presents the context of the astronomical Virtual Observatory (VO), an ambitious international proposal to provide uniform, convenient access to disparate, geographically dispersed archives of astronomical data from software which runs on the computer on the astronomer's desktop. The VO could be of interest for the geodetic community: we present here some of our efforts in this direction that we have recently achieved, concerning the visualization of time series obtained from the analysis of space geodetic techniques. Some of these products are now natively built and archived following the data format recommended by IVOA, the VO-Table format. We present this format, which is based on the XML format, and we list the reasons why we chose to use it. Astronomers using that Virtual Observatory are now organized within an international association called the International Virtual Observatory Alliance (IVOA). As noted on the IVOA website (http://www.ivoa.net/), IVOA was formed in June 2002 with a mission to "facilitate the international coordination and collaboration necessary for the development and deployment of the tools, systems and organizational structures necessary to enable the international utilization of astronomical archives as an integrated and interoperating virtual observatory