The following CryoSat orbit files are available to support data analysis, and planning and airborne campaign execution:

• The Reference Orbit: The Reference Orbit file contains the orbit parameters for each planned orbit, plus the Orbit State Vectors (OSV) for each orbit for the duration of a complete CryoSat orbit repetition cycle (369 days). It is used for planning the main CryoSat instruments and it is generated at the beginning of every orbital repetition cycle around two months before the current file expires. The Reference Orbit is suitable for planning long-term in-situ validation campaigns. At the Polar Regions, the ground track error is within 1 km.


• The Reference Ground Track: This file contains the Reference Orbit expressed in latitude and longitude with 2 seconds, 10 seconds or 60 seconds sampling interval. At the Polar Regions, the ground track error is within 1 km.


• FOS Predicted Orbit: The FOS (Flight Operation Segment) Predicted Orbit is a high accuracy orbit prediction generated closer to the time of the overpass. The file contains OSVs. It is generated every day, and contains one OSV per orbit, located at (or very near to) the Ascending Node. This means that predicted OSVs for a given day are updated 30 times, with increasing accuracy. The coverage is for 30 days starting at the generation time. With respect to the Reference Orbit, the accuracy of the ground tracks is much higher. It can therefore be used to finalise flight lines during validation campaigns to maximise collocation with the satellite acquisition a few weeks in advance.

The ground tracks and the software to generate them are stored on the CryoSat Cal/Val server: ftps://calval-pds.cryosat.esa.int.

Please send an e-mail to EOHelp@esa.int to obtain a personal ftps username and password