This product was generated by the Centre de Traitement Doris Poseidon (CTDP).
It is used to obtain the satellite orbital parameters (lat, long, height and height rate) by using orbit computation routines.
The latest Envisat Precise Orbits products are available in GDR-E version (POE or DOR_VOR_AX_e) which is the one recommended to use. Also the previous GDR-D version (DOR_VOR_AX_d) is still available to users.
The most significant changes relative to the GDR-E standards concern the new ocean tide model (FES2012) and the updated gravity field (a new mean model from CNES/GRGS spanning 12 years of GRACE data including the drifts terms). The new standards significantly improve all POD metrics and, most important, the consistency of Envisat Altimeter Sea Surface Height (SSH) with that of Jason-1 and Jason-2 Altimeter missions. The file size is 0.2 Mbytes per orbit.
See further details in the readme file for Envisat DORIS Precise Orbit Determination files.