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Ocean Surface Topography from Space
Improvement of Precise Orbit Determination Across the TOPEX/Poseidon, Jason Missions and Development of a Seamless Altimeter Record


Frank Lemoine - (Goddard Space Flight Center)

  Brian Beckley
Stavros Melachroinos
Nikita Zelensky
(SGT, Inc.)
(SGT, Inc., Science Division )
(SGT, Inc.)
  Gary Mitchum
Tonie van Dam
Pascal Willis
Marek Ziebart
(University of South Florida, College of Marine Science)
(University of Luxembourg, Faculté des Sciences, de la Technologie et de la Communicati)
(Institut de Physique du Globe de Paris, Geophysique Spatiale et Planetaire)
(University College London, Civil, Environmental and Geomatic Engineering)


The quality and the precision of the satellite orbit is a critical component of the OSTM mission and provides the central reference frame for the altimeter data. Over the 20-25 year time span that comprises the TOPEX/Poseidon, Jason-1, Jason-2 (OSTM), and Jason-3 missions, it is essential that the orbits be in a consistent and stable reference frame, calculated with a state of the art set of geophysical standards. By providing orbits of the highest accuracy and consistency possible, this investigation advances the OSTST goal of providing the best possible satellite-derived ocean surface topography data set. For this investigation we propose to

  1. investigate how to apply a consistent and sufficiently detailed model of time-variable gravity of the Earth across the TOPEX and Jason missions from 1992 to 2016;
  2. evaluate and characterize the error on the orbits and the altimeter data of the forward modeling of the Earth s center of mass motion, not presently included in the GDR-C or GDR-D standards;
  3. validate the performance of the tracking systems on Jason-3 by processing data from all tracking systems (SLR, DORIS, GPS and altimeter crossovers), and inter-compare the system performance with Jason-2 and Jason-1;
  4. produce a consistent set of orbits for Jason-2 & Jason-3 during the tandem phase to support the calibration of the altimeter;
  5. on an-ongoing basis validate the orbit POE s produced by the Jason-2 & Jason-3 missions for the project GDR's;
  6. test other force and measurement model improvements including : a) the application of next-generation satellite surface force models that reduce the impact of the non-conservative forces, b) updates to the tracking network terrestrial reference frame (TRF), with each new realization of the International Terrestrial Reference Frame;
  7. produce an updated set of orbits and geophysical standards based on the preceding analyses, and test their application not only on the Jason satellites and TOPEX, but also on Envisat/SENTINEL-3 and Cryosat-2.

The products from this investigation will include:

  1. Precise orbits for Jason-2 and Jason-3 on an ongoing basis and especially during the tandem calibration phase using current mission standards or easily implemented updates;
  2. Improved orbits for TOPEX/Poseidon and all the Jason satellites (1992 - 2016) using the best possible representation of time-variable gravity, improved surface force modeling, updated terrestrial reference frame and other improvements;
  3. A complete orbit modeling error budget and an assessment of its impact on short-term and long-term estimates of mean sea level change.

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