Abstract's details
CMEMS Level-3 Near-Real-Time Significant Wave Height and Spectral Parameters derived from altimetry and SAR measurements
CoAuthors
Event: 2019 Ocean Surface Topography Science Team Meeting
Session: Application development for Operations
Presentation type: Type Poster
Contribution: not provided
Abstract:
A near-real-time wave service started in July 2017 in the frame of the Copernicus Marine Environment Monitoring Service (CMEMS). Handled by the WAVE-TAC (Thematic Assembly Center), a partnership between CLS and IFREMER, it provides near-real-time wave products derived from altimetry and SAR measurements.
Based on the Level-2 products, significant wave heights (SWH) from altimetry Jason-3, Sentinel-3A and -3B, Saral/AltiKa and Cryosat-2 missions are processed and distributed on CMEMS catalogue approximately 3 hours after the measurements, for operational applications. The 1Hz along-track Level-3 product available for each mission is quality flagged, inter-calibrated between altimeter missions and with respect to in-situ measurements and noise-filtered. This product will soon be upgraded with a state-of-the-art denoising method described in Quilfen et al. 2018 and Quilfen and Chapron 2019. This method is based on Empirical Mode Decomposition and preserves the meso- and sub-mesoscale geophysical signal. The new Level-3 SWH product will include both filtered and unfiltered SWH and a new variable quantifying the uncertainty related to the level of noise. This product is validated against in-situ buoy measurements and between altimeters at cross-over points.
In addition to the altimeters SWH, Level-3 SAR wave products are produced using the Level-2 directional wave spectra processed using Sentinel-1A and –1B acquisitions in a specific Wave mode. From the integral parameters estimated for each wave partition (significant wave height, peak period and peak direction), wave observations whose SWH is larger than 30 cm and peak wavelength is larger than 200 m are gathered according to the swell field they belong to. This is based on back-propagation in space and time using great circle theory: wave measurements converge to their storm source. This association in swell fields enables filtering out wave observations inconsistent with respect to the overall swell distribution. The accuracy of the Level-3 propagated integral parameters is estimated statistically using numerical wave model WaveWatch3 and over a few swell fields of interest using also in-situ measurements.
This presentation will describe the processing, the characteristics and the validation of these different wave products, suitable for several applications such as near-real-time assimilation in numerical wave models.
Based on the Level-2 products, significant wave heights (SWH) from altimetry Jason-3, Sentinel-3A and -3B, Saral/AltiKa and Cryosat-2 missions are processed and distributed on CMEMS catalogue approximately 3 hours after the measurements, for operational applications. The 1Hz along-track Level-3 product available for each mission is quality flagged, inter-calibrated between altimeter missions and with respect to in-situ measurements and noise-filtered. This product will soon be upgraded with a state-of-the-art denoising method described in Quilfen et al. 2018 and Quilfen and Chapron 2019. This method is based on Empirical Mode Decomposition and preserves the meso- and sub-mesoscale geophysical signal. The new Level-3 SWH product will include both filtered and unfiltered SWH and a new variable quantifying the uncertainty related to the level of noise. This product is validated against in-situ buoy measurements and between altimeters at cross-over points.
In addition to the altimeters SWH, Level-3 SAR wave products are produced using the Level-2 directional wave spectra processed using Sentinel-1A and –1B acquisitions in a specific Wave mode. From the integral parameters estimated for each wave partition (significant wave height, peak period and peak direction), wave observations whose SWH is larger than 30 cm and peak wavelength is larger than 200 m are gathered according to the swell field they belong to. This is based on back-propagation in space and time using great circle theory: wave measurements converge to their storm source. This association in swell fields enables filtering out wave observations inconsistent with respect to the overall swell distribution. The accuracy of the Level-3 propagated integral parameters is estimated statistically using numerical wave model WaveWatch3 and over a few swell fields of interest using also in-situ measurements.
This presentation will describe the processing, the characteristics and the validation of these different wave products, suitable for several applications such as near-real-time assimilation in numerical wave models.