DORISINTRODUCTION The CNES (Centres Nationale d'Etudes Spatiales) in partnership with the IGN (Institut Geographique National), CLS and GRGS operate the DORIS System. It was designed to foster dialogue between IDS (International Doris Service) partners and DORIS system users in the fields of orbit determination and accurate location or applications relating to the field of gravity, modelling the ionosphere or troposphere and many more applications. DESCRIPTION of DORIS DORIS is a Doppler satellite tracking system developed for precise orbit determination and precise ground location. It is onboard the TOPEX/POSEIDON, Jason-1 and ENVISAT altimetry satellites and the remote sensing satellites SPOT-2, SPOT-4 and SPOT-5. It also flew with SPOT-3. DORIS was developed to meet the need for accurate location on Earth and high-precision orbit determination. Following its inclusion as a new technique for the International Earth Rotation Service (IERS, regularly submit their results to the IERS, either with respect to polar movement or to track coordinates and speed of stations. Two IERS data centres are providing the scientific community with DORIS measurements for several years, namely NASA/CDDIS and IGN/LAREG. DORIS Data are currently available through 2 IERS Data Centers. DORIS has been included since 1994 as a new IERS technique. ITRF94 was the first realization of the International Terrestrial Reference System with computed DORIS data. IGN/LAREG Data Center (France) and GSFC/CDDIS Data Center (USA). | 
