The POE, or Precise Orbit Ephemeris, is calculated using different arc lengths depending on the mission:
- 10-day arcs for Topex, Jason and Spot satellites,
- 7-day arcs for Envisat, Cryosat-2, Hy-2a.
The delay is usually 2 to 4 week from the beginning of the arc in order to take into account the latest environmental data in the solution.
Data delivery reports are distributed with the DORISreport mailing list (find here information about the mailing list)
The POE orbit is obtained using all the tracking techniques available for a given satellite:
- Doris only for Spot satellites,
- Doris+ SLR for Topex, Envisat, Cryosat-2, Hy-2a,
- Doris+SLR+ GPS for Jason-1 and Jason-2
Measurement models include ITRF coordinates for SLR and DORIS and JPL's solution at IGS for GPS ephemeris and clocks. Station coordinates are corrected for displacements induced by solid earth tides and ocean loading.
- For Doris measurements a frequency and a troposphere bias per pass are estimated.
- For SLR, a bias per pass is also estimated for a few low quality stations in the network.
Dynamic models for all the satellites follow the standards defined for the Geophysical data Records (GDRs) altimetry products.
The dynamic parameterization also differs for different missions, as it depends on the amount of the available tracking data.
The details of the successive configurations and GDR standards can be found in the section Observations on the Documents page
Satellite and station performance plots for the DORIS missions from the SSALTO ground segment (number of passes, number of observations, residuals) are regularly updated and made available on this website. You may also use the interactive POE tool to create and display graphs from these outputs.