Improving Conventional Altimetry SSH observability: Global assessment of SSH datasets derived from innovative LRM retrackers

Matthias Raynal (CLS, France)


Hélène Roinard (CLS, FRANCE); Emeline Cadier (CLS, FRANCE); Sylvie Labroue (CLS, FRANCE); Pierre Thibault (CLS, FRANCE); Fanny Piras (CLS, FRANCE); Nicolas Picot (CNES, FRANCE); François Boy (CNES, FRANCE)

Event: 2019 Ocean Surface Topography Science Team Meeting

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

Presentation type: Type Poster

Since many years, altimetry constellation is delivering relevant measurements to monitor the ocean large scale surface topography. More recently, with our understanding of the oceanic structures, these needs have evolved toward a better characterization of the oceanic mesoscale and sub mesoscales dynamic, over open and coastal areas. To answer this problematic, many progresses were made in the instrumental design domain. Thanks to the new generation of Delay Doppler altimeters (first time onboard on Cryosat-2 mission), the instrumental noise and spectral bump error were significantly reduced. On the other hand, to continue exploiting the recent and past LRM datasets, a lot of work has been dedicated to improve the retracking methods.

Today, for ocean application, three main algorithms, approaches could be distinguished:
- The ALES (Adaptive Leading Edge Subwaveform) retracker (Passaro et al. Year)
- The two-passes retracker (Sandwell et al., 2005)
- The adaptive retracker (Thibault et al., OSTST 2018)

These three retrackers represent state of the art of research on this topic and they all have different strength and weaknesses depending on the considered application. Thus, this paper aims at reviewing and comparing their Sea Surface Height retrieval performances with the same metrics. The assessment will be done with classical metrics at 1 Hz at global scales to assess the improvement compared to the existing MLE4 operational datasets. This will complement the assessment done by Smith et al (OSTST 2017) that focused on performances of several retrackers at small spatial scales. We highlight improvements and limitations considering different fields of applications: mesoscale observability, climate applications, coastal approaches, continuity performances over different surface (estuaries, ocean to sea ice transitions).


Poster show times:

RoomStart DateEnd Date
The Gallery Tue, Oct 22 2019,16:15 Tue, Oct 22 2019,18:00
The Gallery Thu, Oct 24 2019,14:00 Thu, Oct 24 2019,15:45
Matthias Raynal