Global assessment of Jason-1 GDR-E Reprocessing

Hélène Roinard (CLS, France)


Sabine Philipps (CLS, France); Michael Ablain (CLS, France); Emilie Bronner (CNES, France); Jean-Damien Desjonqueres (CNES, France); Nicolas Picot (CNES, France)

Event: 2016 Ocean Surface Topography Science Team Meeting

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

Presentation type: Type Oral

Jason-1 was launched in December 2001 and routinely monitored the ocean until June 2013, date of its final measurement. It first flew on the historical ground track, as a successor of TOPEX/Poseïdon mission. In February 2009, Jason-1 assumed a new orbit midway between its original ground track but with a time lag of approximately 5 days with Jason-2 to provide an optimal coverage for Near Real Time (NRT) applications. In May 2012, it left its repeat track orbit for a geodetic phase until it was finally decommissioned.

Jason-1 time series continued the extraordinary sea level record first initiated by TOPEX/Poseïdon mission. Even if this mission is finished, the quality of such a record can still be improved, as science progresses are continuously made.
For the last two years, CNES and NASA have worked on the reprocessing of the new Jason-1 release of Geophysical Data Records (GDR-E). The latest standards available are used, and in this study, the reprocessed dataset is analyzed and compared to previous versions as well as Jason-2 data, and particularly:
- The assessment of the standard E orbit which uses a new gravity field model that should enhance the regional mean sea level by reducing the basin scale discrepancies.
- The impact of the new ocean tides, sea state bias and mean sea surface.
- The radiometer related corrections and their impact
- The newly available corrections from ERA-Interim model (useful for long term studies)

Variance of ascending/descending SSH differences at 10 days crossovers is reduced by 1.3cm2 and along-track standard deviation of Sea Level Anomaly (SLA) is also reduced showing an improvement of the mesoscale performance. Jason-1 GDR-E data are more homogeneous to Jason-2 data thanks to sea state bias and ionosphere correction, though geographically correlated differences due to orbit differences remain. Global Mean Sea Level (GMSL) trend (using GDR-E data from the repeat ground-track) is now 2.78 mm/yr. Furthermore, the amplitude of the 58.77-day Mean Sea Level (MSL) signal at global and regional scales is significantly reduced.

Oral presentation show times:

RoomStart DateEnd Date
Auditorium Wed, Nov 02 2016,17:15 Wed, Nov 02 2016,17:30
Hélène Roinard