Progress in Retracking TOPEX for the Climate Data Record

Philip Callahan (Jet Propulsion Laboratory, United States)


Brent Williams (Jet Propulsion Laboratory, USA)

Event: 2014 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Measurement and retracking (SAR and LRM)

Presentation type: Type Oral

We will report on progress in producing the TOPEX Climate Data Record product. The main effort for this product is retracking the data to account for waveform leakages and point target response (PTR) changes.

The effects of the leakages were found to have a limiting effect on the range of data that could be reliably used in the CalSweep measurements of the PTR. This also affects the Cal-1 data that are available throughout both Alt-A and Alt-B lifetimes. A physical model of the PTR change based on changes in phase between the I and Q channels, originally suggested by R. Jenson of APL, has been investigated. The model can reproduce much of the observed behavior, but the remaining differences make it unclear whether the model can be used to predict the temporal behavior better than the Cal-1 data. Model results will be displayed.

Methods to extend the PTR beyond the approximately seven usable lobes have been tested to produce the necessary 30 lobes to reach full accuracy. The results of the tests and the selected method will be presented.

Several years of TOPEX data have been retracked with the selected waveform weights and PTRs for initial accuracy assessment and Sea State Bias (SSB) determination. The results of this assessment and the plan for completing the reprocessing will be given. The retracked data with Shannon Brown's latest processing of TMR data, and the latest orbits and tides will be used for a final SSB update. All of these elements will be combined into the TOPEX Climate Data Record product.

The work reported here was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration with funding from the NOAA Climate Data Records program.

Oral presentation show times:

RoomStart DateEnd Date
Ballroom Tue, Oct 28 2014,16:15 Tue, Oct 28 2014,16:27
Philip Callahan
Jet Propulsion Laboratory
United States