Day 4

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Paper title Towards high resolution altimetry wave products: what is hidden below 50km? A multimission approach
Authors
  1. Annabelle Ollivier CLS - Collecte Localisation Satellites Speaker
  2. Adrien NIGOU Celad for CLS
  3. Marie-Isabelle Pujol CLS
  4. Alice Dalphinet Meteo France, CNRM
  5. Gérald Dibarboure CNES - Centre national d'études spatiales, France
  6. François SOULAT CLS - Collecte Localisation Satellites
  7. Alejandro BOHE CNES
  8. Fabrice Ardhuin LOPS - CNRS
  9. Fanny Piras Collect Localisation Satellites (CLS)
  10. Ngan TRAN CLS - Collecte Localisation Satellites
Form of presentation Poster
Topics
  • A8. Ocean
    • A8.14 Remote-sensing of Ocean Waves and their Applications
Abstract text In the Sea State community, the literature usually assumes that altimetry waves at 1Hz is dominated by noise (Ardhuin et al. 2019) and most studies tackle this issue by filtering these data up to 50km at least (Quilfen et al. 2018, Dodet et al. 2020). It is also known that the fading noise has a real impact on correlated errors at these scales (Quartly et al. 2019), with an impact on SLA estimates that can empirically be reduced by methods described in Zaron et al. or Tran et al. 2021.

Is this presentation, we propose to process the 20Hz resolution altimetric data and to look deeper into this HF content. After a 5Hz compression, we analyze the frequential content and their geographical signatures. We also take a particular care to data selection, an essential step for validation purpose (as illustrated in Quartly et al. 2019).

The analysis is multimission oriented. LRM missions are processed with the innovative adaptive retracking (Tourain et al. 2021). It also deals with Doppler SAR altimetry observations, also impacted by the sea sate structures (Moreau et al. 2021). The study focuses on Jason3 thanks to SALP CNES project, ENVISAT, in the frame of the innovative Fdr4ALT project and CFOSAT (Hauser et al. 2020).

To better characterize the high frequency signal, we leverage the spectral information (direction and wavelength and partitions) provided by the CFOSAT mission, as well as Sentinel 1 radar imaging. A discussion is carried to determine how these altimetric products could become the next generation of CMEMS WaveTAC products. It also explores the contamination effects on SLA estimates, mainly in the bump frequency, extensively described in Dibarboure et al 2014.

The processing of these new 5Hz L2P products is presented. Their quality over coastal areas is illustrated and demonstrated. Their added value offshore is highlighted and offered to discussion with other international teams (for assimilation and/or validation, climate or coastal communities…) via demonstration products available on Aviso web site. Give it a try!