Global Calibration and Validation of Reprocessed TOPEX Data

Matthieu Talpe (Jet Propulsion Laboratory, United States)


Jean-Damien Desjonquères (Jet Propulsion Laboratory, USA); Shailen Desai (Jet Propulsion Laboratory, USA); Bruce Haines (Jet Propulsion Laboratory, USA); Philip Callahan (Jet Propulsion Laboratory, USA); Josh Willis (Jet Propulsion Laboratory, USA)

Event: 2019 Ocean Surface Topography Science Team Meeting

Session: Regional and Global CAL/VAL for Assembling a Climate Data Record

Presentation type: Type Oral

In this presentation, we show results from the calibration and validation (cal/val) of the most recent reprocessing of TOPEX side A and B measurements. This latest reprocessing relies on numerical retracking (see presentation from Desjonqueres et al. in the Instrument Processing splinter).

Three approaches are highlighted for this cal/val study. First, we examine results of independent TOPEX cal/val: time series of cycle-averaged statistics and geographic patterns to assess the stability of sigma0, altimeter wind speed, significant wave height (SWH), wet path delay, etc. Second, we present results from Jason-1 vs TOPEX inter-mission cal/val: we utilize the tandem period that extends 20 cycles (TOPEX cycles 344-364 and Jason-1 cycles 1-20) to directly compare respective values of uncorrected sea surface height (orbit – range – MSS), sea surface height anomaly (SSHA), sigma0, SWH, etc. Third, we use an independent measure of geocentric SSHA provided by the Harvest platform (see also presentation from Haines et al. in Cal/Val splinter).

Time series of globally-averaged SSHA crossovers show that the newly retracked SSHA measurements are an improvement over the original TOPEX Geophysical Data Records (GDRs). This improvement is corroborated over the Jason-1 tandem phase, during which the standard deviation of SSHA differences (TOPEX vs. Jason-1) are smaller. Furthermore, the geographical distribution of TOPEX-Jason-1 uncorrected sea surface height differences reveal that north/south hemispherical biases in the altimeter measurements of range, SWH, and sigma0 observed in the original TOPEX GDRs have been greatly reduced by this latest retracking approach. We also explore the influence of different orbit solutions on these geographical distributions as an indicator of the amplitude of remaining orbit errors.


Oral presentation show times:

Room Start Date End Date
The Forum Wed, Oct 23 2019,11:00 Wed, Oct 23 2019,11:15
Matthieu Talpe
Jet Propulsion Laboratory
United States