February 24, 2017


Altimetry and Precise Positioning Service


SALP (Service d'Altimetrie et Localisation Precise: altimetry and precise positioning service) is responsible for the implementation and sustainment of operational systems for altimetry missions, as well as for the development of equivalent systems for upcoming missions.

  • Altimetry
    (GFO, Jason-1, ENVISAT; Jason-2, CRYOSAT2, AltiKa and Jason-3, ...).

  • Doris, precise positioning reference system
    (Spot-2, Spot-4, Jason-1, ENVISAT, Spot-5; Jason-2, CRYOSAT2, AltiKa, and Jason-3, ...).

  • Doris, on board real-time positioning system
    (Spot-4, Spot-5 H2A, H2B and Pleiades, ...).

SALP generates, integrates, validates, distributes, archives and adds value to the data.

It operates within an international cooperation framework (with NASA, ESA, EUMETSAT, NOAA, etc.), with the permanent goal of satisfying a broad set of users from scientists to operational users.

Satellites used by SALP
Satellites used by SALP

SALP activities

SALP is a multi-mission series project

SALP covers:

  • Operations and sustainment of systems activities
    • Jason-1 mission
    • Doris and Poseidon instruments
    • Doris ground beacon network
    • Acquisition, production, validation, archiving and distribution of data
    • SALP mission centre
  • Setup of new missions activities
    • Jason-2
    • AltiKa
    • Cryosat-2
  • Study activities
    • Doris
      PANDOR/MORDOR activities: Doris 1.0 measurements processing chain which enables multi-satellites timing as well as on board and ground USO characterization.
      Study activities for the implementation of a remote management system for standard beacons.
    • Altimetry
      • Study  geared towards improving data processing of altimetry measurements as well as models and associated corrections (tide, troposphere, etc.)
      • Preparation and validation of specific data processing for future missions.
      • Preparation if needed of reprocessing campaigns
      • Creation of new products (for example dedicated to altimetry in coastal areas or continental waters)
    • Data reprocessing activities to implement the best standards available and to maintain uniform series over time.
    • Communication activities
      • Promotion of altimetry and its scientific and technical possibilities
      • Informing and training of AVISO products users
      • Development of relations with scientists and AVISO products users
      • Continuation of relations with NASA, ESA and EUMETSAT teams
      • Outreach
      • Monitoring and evaluating the impact of actions

    DORIS ground station network

    The DORIS system relies on a network of ground beacons (about 60 around the world).

    DORIS beacons network
    DORIS global beacon network

    SALP Mission Centre

    SALP Mission Center is composed of:

    • SSALTO, the multi-mission processing centre housing all the components managed by the CNES' PS/CMI structure
      • CMA: altimetry processing
      • CCI and CCD: Instrument Command / Control
      • SD: Data Server
      • OM: Mission Orbit
      • OS: Housekeeping Orbit
      • AVISO: Catalogue and archiving
      • GDD ENVISAT and IPF_RA2: ENVISAT data processing, catalogue and archiving
    • The other components with CLS as prime contractor
      • DUACS, DAC and GIM: value-added product processing chain
      • DORIS integrity workshop,
      • TMDS and SATD: SPOT and HELIOS TM acquisition
      • CALVAL: Calibration/validation processing chain
    • For future missions (Jason-2,Cryosat-2, AltiKa), new components are under development
      • SPA offline/NRT: altimetry processings
      • STILO: instruments command / control
      • SIMBAD: beacon network management
      • SIPAD-SALTO: Cataloguing, archiving and distribution
      • LTA-CRY2: Cryosat-2 archiving and distribution

    The centre is implemented across the following computing facilities:

    • CNES computing centre
    • CLS facilities

    Evolutions linked to anomaly correction and implementation of evolutions

    • About 20 versions per year across all components
    • Work in synergy with CNES teams involved in altimetry projects (PO/AL, PS/CMI, SB/OR, DSI...) and industry (CLS, etc.)
    • Work interfacing with ESA for F-PAC part (RA-2 altimeter and DORIS instrument on board ENVISAT data processing)

    Data users

    • International scientific community (PIs, co-Is, national), international programmes, International Doris Service (IDS).
    • Meteorology or operational oceanography organizations, Mercator
    • Other data centres and space agencies.
    • Private companies

    Geographical distribution of the data users
    Geographical distribution of the data users