Calibration and Validation of Jason-2 over the First Full Cycle of the Long-Repeat Orbit

Matthieu Talpe (Jet Propulsion Laboratory, United States)

CoAuthors

Jean-Damien Desjonqueres (Jet Propulsion Laboratory, United States); Shailen Desai (Jet Propulsion Laboratory, United States); Bruce Haines (Jet Propulsion Laboratory, United States)

Event: 2018 Ocean Surface Topography Science Team Meeting

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

Presentation type: Type Poster

The Jason-2 mission has been operating in its long-repeat orbit (LRO) since July 2017, yielding global coverage of the marine geoid at a cross-track resolution of about 8 km, while still providing altimetry products of high value for oceanographic applications at the mesoscale level. In this poster, we present a summary of calibration and validation results for the Jason-2 altimetry products over the first full interval of this long-repeat orbit.

We show that Jason-2 measurements both comply with mission requirements and correspond well to Jason-3 in spite of the orbit change and of Jason-2 Safe Hold events. Namely, significant wave height, sigma naught, sea-state bias, the ionospheric correction, and the dry and wet tropospheric correction are stable throughout the first LRO cycle.

Furthermore, the change in Mean Sea Surface (MSS) model on the Jason-2 products, from MSS 2011 to MSS 2015, results in lower noise for sea surface height anomaly (SSHA). SSHA crossover comparisons with Jason-3 products, which still utilize MSS 2011, primarily reveal differences between is the respective MSS models, including: a well-documented bias of approximately 2.4 cm globally and geographically-correlated discrepancies. We apply a consistent MSS model to the Jason-2 and Jason-3 measurements to isolate the residual crossover differences between Jason-2 and Jason-3.

We use internal SSHA crossover differences (i.e., Jason-2 ascending pass versus descending pass) to estimate the fundamental limit of the Jason-2 altimeter system. The variability in crossover differences stems from two main sources: 1) the limitations of the altimeter system and geophysical models (e.g., instrument corrections, sea-state bias, tides, etc.) and 2) natural ocean variability that is inherent to measurements sampled at different times. We consider crossover differences as a function of the time interval between the two measurements being differenced to dissociate these two effects. As expected, at smaller time intervals, the error source originating from ocean variability is reduced, and provides a means to estimate the altimeter system noise for Jason-2. For comparison, this analysis is also applied to the Jason-3 altimeter system.
 

Poster show times:

Room Start Date End Date
Foyer, Salao Nobre & tent Thu, Sep 27 2018,18:00 Thu, Sep 27 2018,20:00
Foyer, Salao Nobre & tent Fri, Sep 28 2018,14:00 Fri, Sep 28 2018,15:00
Matthieu Talpe
Jet Propulsion Laboratory
United States
matthieu.j.talpe@jpl.nasa.gov