Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: results from simulations and CFOSAT/SWIM observations
International audience The accuracy of sea surface parameters retrieved from altimeter missions is predominantly governed by the choice of the so-called "retracking" algorithm, i.e. the model and inversion method implemented to obtain the surface parameters from the backscattered waveform....
Published in: | IEEE Transactions on Geoscience and Remote Sensing |
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fttriple:oai:gotriple.eu:10670/1.hm6y2c 2023-05-15T18:18:08+02:00 Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: results from simulations and CFOSAT/SWIM observations Tourain, Cedric Piras, Fanny Ollivier, Annabelle Hauser, Danièle Poisson, Jean-Christophe Boy, François Thibaut, Pierre Hermozo, Laura Tison, Céline Centre National d'Études Spatiales Toulouse (CNES) Collecte Localisation Satellites (CLS) Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales Toulouse (CNES) SPACE - LATMOS Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS) Centre National d'Etudes Spatiales - Direction Des Lanceurs. (CNES) CNES 2021-01-01 https://doi.org/10.1109/TGRS.2021.3064236 https://hal.archives-ouvertes.fr/hal-03026814v2/file/TGRS_2020_02660.pdf https://hal.archives-ouvertes.fr/hal-03026814 en eng HAL CCSD Institute of Electrical and Electronics Engineers hal-03026814 doi:10.1109/TGRS.2021.3064236 10670/1.hm6y2c https://hal.archives-ouvertes.fr/hal-03026814v2/file/TGRS_2020_02660.pdf https://hal.archives-ouvertes.fr/hal-03026814 other Hyper Article en Ligne - Sciences de l'Homme et de la Société ISSN: 0196-2892 IEEE Transactions on Geoscience and Remote Sensing IEEE Transactions on Geoscience and Remote Sensing, Institute of Electrical and Electronics Engineers, 2021, 59 (12), pp.9927-9940. ⟨10.1109/TGRS.2021.3064236⟩ retracking algorithm CFOSAT SWIM validation nadir altimetry radar ocean geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2021 fttriple https://doi.org/10.1109/TGRS.2021.3064236 2023-01-22T18:41:52Z International audience The accuracy of sea surface parameters retrieved from altimeter missions is predominantly governed by the choice of the so-called "retracking" algorithm, i.e. the model and inversion method implemented to obtain the surface parameters from the backscattered waveform. For continuity reasons, the choice of space agencies is usually to apply the same retracker from one satellite mission to the other to ensure long time homogeneous series. Here, taking the opportunity of a new configuration of the nadir pointing measurements on-board the recently launched CFOSAT satellite with the SWIM (Surface Waves Investigation and Monitoring) instrument (Hauser et al, 2020), the retracking method was upgraded, by implementing a novel algorithm, called "Adaptive" retracker. It combines the improvements brought by Poisson et al (2018) for the estimation of surface parameters from peaked waveforms over sea-ice, improvements in the way the instrumental characteristics are taken into account in the model (mispointing, point target response) and a more accurate consideration of speckle statistics. In this paper, we first show from simulations carried out in the instrumental configuration of SWIM that the Adaptive algorithm has better accuracy and performances than the classical MLE4 algorithm. Then, the geophysical parameters obtained with real data from SWIM are analyzed with comparisons to reference data sets (model and products from altimeters). We show that this new algorithm has several benefits with respect to the classical MLE4 method: no need of look-up tables to correct biases, significant noise reduction on all geophysical variables especially the significant wave height, and performance of inversion over a large set of echo shapes, resulting from standard oceanic scenes as well as highly specular conditions such as over bloom or sea-ice. Article in Journal/Newspaper Sea ice Unknown IEEE Transactions on Geoscience and Remote Sensing 59 12 9927 9940 |
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collection |
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op_collection_id |
fttriple |
language |
English |
topic |
retracking algorithm CFOSAT SWIM validation nadir altimetry radar ocean geo envir |
spellingShingle |
retracking algorithm CFOSAT SWIM validation nadir altimetry radar ocean geo envir Tourain, Cedric Piras, Fanny Ollivier, Annabelle Hauser, Danièle Poisson, Jean-Christophe Boy, François Thibaut, Pierre Hermozo, Laura Tison, Céline Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: results from simulations and CFOSAT/SWIM observations |
topic_facet |
retracking algorithm CFOSAT SWIM validation nadir altimetry radar ocean geo envir |
description |
International audience The accuracy of sea surface parameters retrieved from altimeter missions is predominantly governed by the choice of the so-called "retracking" algorithm, i.e. the model and inversion method implemented to obtain the surface parameters from the backscattered waveform. For continuity reasons, the choice of space agencies is usually to apply the same retracker from one satellite mission to the other to ensure long time homogeneous series. Here, taking the opportunity of a new configuration of the nadir pointing measurements on-board the recently launched CFOSAT satellite with the SWIM (Surface Waves Investigation and Monitoring) instrument (Hauser et al, 2020), the retracking method was upgraded, by implementing a novel algorithm, called "Adaptive" retracker. It combines the improvements brought by Poisson et al (2018) for the estimation of surface parameters from peaked waveforms over sea-ice, improvements in the way the instrumental characteristics are taken into account in the model (mispointing, point target response) and a more accurate consideration of speckle statistics. In this paper, we first show from simulations carried out in the instrumental configuration of SWIM that the Adaptive algorithm has better accuracy and performances than the classical MLE4 algorithm. Then, the geophysical parameters obtained with real data from SWIM are analyzed with comparisons to reference data sets (model and products from altimeters). We show that this new algorithm has several benefits with respect to the classical MLE4 method: no need of look-up tables to correct biases, significant noise reduction on all geophysical variables especially the significant wave height, and performance of inversion over a large set of echo shapes, resulting from standard oceanic scenes as well as highly specular conditions such as over bloom or sea-ice. |
author2 |
Centre National d'Études Spatiales Toulouse (CNES) Collecte Localisation Satellites (CLS) Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales Toulouse (CNES) SPACE - LATMOS Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS) Centre National d'Etudes Spatiales - Direction Des Lanceurs. (CNES) CNES |
format |
Article in Journal/Newspaper |
author |
Tourain, Cedric Piras, Fanny Ollivier, Annabelle Hauser, Danièle Poisson, Jean-Christophe Boy, François Thibaut, Pierre Hermozo, Laura Tison, Céline |
author_facet |
Tourain, Cedric Piras, Fanny Ollivier, Annabelle Hauser, Danièle Poisson, Jean-Christophe Boy, François Thibaut, Pierre Hermozo, Laura Tison, Céline |
author_sort |
Tourain, Cedric |
title |
Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: results from simulations and CFOSAT/SWIM observations |
title_short |
Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: results from simulations and CFOSAT/SWIM observations |
title_full |
Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: results from simulations and CFOSAT/SWIM observations |
title_fullStr |
Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: results from simulations and CFOSAT/SWIM observations |
title_full_unstemmed |
Benefits of the Adaptive algorithm for retracking altimeter nadir echoes: results from simulations and CFOSAT/SWIM observations |
title_sort |
benefits of the adaptive algorithm for retracking altimeter nadir echoes: results from simulations and cfosat/swim observations |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://doi.org/10.1109/TGRS.2021.3064236 https://hal.archives-ouvertes.fr/hal-03026814v2/file/TGRS_2020_02660.pdf https://hal.archives-ouvertes.fr/hal-03026814 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
Hyper Article en Ligne - Sciences de l'Homme et de la Société ISSN: 0196-2892 IEEE Transactions on Geoscience and Remote Sensing IEEE Transactions on Geoscience and Remote Sensing, Institute of Electrical and Electronics Engineers, 2021, 59 (12), pp.9927-9940. ⟨10.1109/TGRS.2021.3064236⟩ |
op_relation |
hal-03026814 doi:10.1109/TGRS.2021.3064236 10670/1.hm6y2c https://hal.archives-ouvertes.fr/hal-03026814v2/file/TGRS_2020_02660.pdf https://hal.archives-ouvertes.fr/hal-03026814 |
op_rights |
other |
op_doi |
https://doi.org/10.1109/TGRS.2021.3064236 |
container_title |
IEEE Transactions on Geoscience and Remote Sensing |
container_volume |
59 |
container_issue |
12 |
container_start_page |
9927 |
op_container_end_page |
9940 |
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