ERS1 Global Sea Surface Heights


Revised March 14, 2001

NASA/GSFC Pathfinder ERS-1 PhaseC Georeferenced Altimetry Heritage: CERSAT OPR 3.0
Version 5.1 ERS-1 PhaseC

Version 5.1 Updates from Version 5.0:

  • Ocean tide replaced with GSFC GOT99.3 resulting in additional recovery of inland sea areas.

    Version 5.0 Updates from Version 4.0:

  • Time tag bias modified from 1.7 ms to 1.5 ms
  • Significant wave height corrected (P. Queffeulou, Quality of Long-Term Satellite Wind and Wave Measurements, ERS-Envisat Symposium, Oct., 2000)and EM Bias correction re-computed with Gaspar BM3 model.

    Version 4.0 Updates from Version 3.0:

  • UTCSR Mean Sea Surface replaced with GSFC00.1 MSS
  • Cross track gradient correction recomputed from GSFC00.1 cross track slopes.
  • Ocean tide of Schrama,Ray 1996 replaced with GOT99.2.
  • Inter-mission and inter-version (Cersat OPR) biases have been applied to produce a more homogeneous dataset with respect to ERS-2 and OPR Version 6 data products (IFREMER report CLS/DOS/NT/98.070):

    ERS-1 Phase C Sea Surface Height Version 4.0 =

    ERS-1 Phase C Sea Surface Height Version 3.0
    - 409 mm (absolute range calibration)
    + 24 mm (range correction for OPR Version 3)

    Version 3.0 Updates from Version 2.0:

  • Altimetric Range Corrections Applied:
    Ultra Stable Oscillator (USO) Drift and Scanning Point Target Response (SPTR) Correction

    Version 2.0 Updates from Version 1.1:

  • Major update: Sea surface height is based on Delft DGM-E04 orbits with 1.7 ms time tag bias applied.
  • Ocean tide flag bit (see flag.doc)

    Version 1.1 Updates from Version 1.0:

  • SSH based on UT CSR TEG-3 orbits
  • SSH corrected for 1.6 ms time tag error..
  • Recovery of data previously lost to orbit interpolation error.
  • Retain SSH residuals > 3.0 m with respect to mean sea surface.

    NASA/GSFC Pathfinder ERS-1 PhaseG Georeferenced Altimetry Heritage: CERSAT OPR 6.0
    Version 3.1 ERS-1 PhaseG

    Version 3.1 Updates from Version 3.0:

  • Ocean tidel model replaced with GOT99.3 resulting in recovery of additional inland sea areas.

    Version 3.0 Updates from Version 2.0:

  • Time tag bias modified from 1.7 ms to 1.5 ms
  • Significant wave height corrected (P. Queffeulou, Quality of Long-Term Satellite Wind and Wave Measurements, ERS-Envisat Symposium, Oct., 2000)and EM Bias correction re-computed with Gaspar BM3 model.

    Version 2.0 Updates from Version 1.0:

  • UTCSR Mean Sea Surface replaced with GSFC00.1 MSS
  • Cross track gradient correction recomputed from GSFC00.1 cross track slopes.
  • Ocean tide of Schrama,Ray 1996 replaced with GOT99.2.
  • Inter-mission and inter-version (Cersat OPR) biases applied to produce a more homogeneous dataset with respect to ERS-2 and OPR Version 6 data products (IFREMER report CLS/DOS/NT/98.070):

    ERS-1 Phase G Sea Surface Height Version 2.0 =

    ERS-1 Phase G Sea Surface Height Version 1.0
    - 409 mm (absolute range calibration)

    Version 1.0

  • Sea surface height is based on Delft DGM-E04 orbits with 1.7 ms time tag bias applied.
  • Altimetric Range Corrections Applied: Ultra Stable Oscillator (USO) Drift Scanning Point Target Response (SPTR) Correction

    PhaseC Parameter File Record Description
    Variable Word Size Bytes
    Along Track Index I*2 2
    Revolution Number I*2 2
    Sea Surface Residual Height Array (mm) I*2 36

    PhaseG Parameter File Record Description
    Variable Word Size Bytes
    Along Track Index I*2 2
    Revolution Number I*2 2
    Sea Surface Residual Height Array (mm) I*2 26

    Algorithms and corrections used are available here

    Editing was performed on the data based on these criteria.

    A flagword for each sea surface residual height was set based on certain tests.