TOPEX/POSEIDON Colinear Sea Surface Heights


Revised July 18, 2002

NASA/GSFC Pathfinder TOPEX/Poseidon Georeferenced Altimetry
Version 9.0

Version 9.0 Updates from Version 8.8

  • Cycles 1 - 356 (09/23/1992 - 05/24/2002)
  • TMR correction recomputed with revised TB18 (Ruf, 2000)
  • EM Bias recomputed from corrected SWH (Quefflou, 1999) for ALT B and during period of ALT A drift.
  • Bias of 7 mm applied to ALT B sea surface height (Mitchum, 1999)

    Version 8.8 Updates from Version 8.7

  • Cycles 1 - 320
  • GOT00.2 ocean tide model

    Version 8.7 Updates from Version 8.6

  • Cycles 1 - 314

    Version 8.6 Updates from Version 8.5

  • Cycles 1 -308 with exception to POSEIDON cycle 307.

    Version 8.5 Updates from Version 8.4

  • Cycles 1 -304 with exception to POSEIDON cycle 299.
  • GOT99.3 ocean tide model.

    Version 8.4 Updates from Version 8.2

  • Cycles 1 -300 with exception to POSEIDON cycle 299.
  • Delete ALT B observations erroneously set as ALT A in TOPEX GDR.

    Version 8.2 Updates from Version 8.1

  • Cycles 1 -294.

    Version 8.1 Updates from Version 8.0

  • Cycles 1 - 286 with exception to POSEIDON cycle 278.
  • Reprocessed cycles 277 -284 for revised TOPEX sigma0 calibration (http://topex.wff.nasa.gov/docs).

    Version 8.0 Updates from Version 7.0

  • Contains cycles 1 -282.
  • UTCSR Mean sea surface reference replaced with GSFC00.1 MSS
  • Cross track gradient correction recomputed with GSFC00.1 MSS>

    Version 7.0 Updates from Version 6.1

  • Contains cycles 1 -276.
  • Ocean tide updated with GOT99.2

    Version 6.1 Updates from Version 6.0

  • Contains cycles 1 -270.

    Version 6.0 Updates from Version 5.1

  • A 15mm bias was inadvertently applied to the POSEIDON 10Hz data on the JPL PODAAC MGDRB for cycles 138 and greater causing the georeferenced 1Hz sea surface heights to be 15 mm lower. The Pathfinder data set has been corrected for this bias on the affected POSEIDON cycles.
  • The TOPEX/POSEIDON Science Working Team presented results that indicates that the AlT B data (cycles greater than 235) is biased by approximately 8.5 +/- 2 mm with respect to the end of Alt A when all corrections are applied consistently for Side A & B. This bias has NOT been corrected for in the Pathfinder data set, thus Alt B sea surface height observations are LOWER than the end of ALT A by approximately 1 cm.
  • Dataset contains cycles 1 through 254, with exceptions of cycle 118 and POSEIDON cycles 234 and 243.

    Sea surface heights were computed with JGM3 orbits. The precise orbital ephemerides for Topex/Poseidon are identical to those used in the second version of the T/P Geophysical Data Records, as computed by the Space Geodesy Branch at NASA/GSFC. These ephemerides are computed for nominal 10-day arc segments, corresponding to the groundtrack repeat period of the satellite. They are based on force models derived from the JGM-3 earth gravity model, a T/P-based ocean-tide model, a sophisticated `box-wing' satellite model for drag and radiation forces, and on laser and doppler tracking data. Earlier versions of these orbits were described by Nerem et al. [1993] and Tapley et al. [1994a]; those papers give many further details on the ephemeris calculations. The present version of the orbits is described by Marshall et al. [1995], who examine in detail the error budget while presenting strong evidence for a radial orbit accuracy of about 3 cm rms.

    Each record contains an array of sea surface heights for the 356 ten day repeat cycles at a single location defined by a revolution number and along track index:

    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*2 712

    Description of algorithms are available.

    Editing was performed on the data based on these criteria.

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