Consulta: creatorFacets:"Autret, Emmanuelle"
Registros recuperados: 15
Data/hora: 13/06/2024 07:27:21

Exploring Machine Learning to Correct Satellite-Derived Sea Surface Temperatures
Provedor de dados: 5
Autores: Picart, Stephane Saux; Tandeo, Pierre; Autret, Emmanuelle; Gausset, Blandine.
Machine learning techniques are attractive tools to establish statistical models with a high degree of non linearity. They require a large amount of data to be trained and are therefore particularly suited to analysing remote sensing data. This work is an attempt at using advanced statistical methods of machine learning to predict the bias between Sea Surface Temperature (SST) derived from infrared remote sensing and ground “truth” from drifting buoy measurements. A large dataset of collocation between satellite SST and in situ SST is explored. Four regression models are used: Simple multi-linear regression, Least Square Shrinkage and Selection Operator (LASSO), Generalised Additive Model (GAM) and random forest. In the case of geostationary satellites for...
Tipo: Text
Palavras-chave: Machine learning; Systematic error; Sea surface temperature; Random forest.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00426/53797/54721.pdf

Operational oceanography in France : the Coriolis project
Provedor de dados: 5
Autores: Coatanoan, Christine; Carval, Thierry; Petit De La Villeon, Loic; Autret, Emmanuelle; Gouriou, Yves; Gourmelen, Loic.
An operational oceanographic system is being developed in France to monitor and forecast ocean behavior. It is composed of three projects: - Sea-surface observation using satellite sensors, - ln situ measurements from ships, moored or drifting autonomous systems, - Assimilation of in-situ and satellite data in an ocean circulation modal.  Coriolis contributes to the in situ part of this system,with the objective of developing continuous,automatic,and permanent observation networks. The data collected will enable water properties to be mapped, such as temperature, and ocean circulation. (NOT CONTROLLED OCR]
Tipo: Text
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/acte-4691.pdf

Diurnal warm-layer events in the western Mediterranean and European shelf seas
Provedor de dados: 5
Autores: Merchant, C. J.; Filipiak, M. J.; Le Borgne, P.; Roquet, H.; Autret, Emmanuelle; Piolle, Jean-francois; Lavender, S.
We characterize near-surface ocean diurnal warm-layer events, using satellite observations and fields from numerical weather forecasting. The study covers April to September, 2006, over the area 11 degrees W to 17 degrees E and 35 degrees N to 57 degrees N, with 0.1 degrees cells. We use hourly satellite SSTs from which peak amplitudes of diurnal cycles in SST (dSSTs) can be estimated with error similar to 0.3 K. The diurnal excursions of SST observed are spatially and temporally coherent. The largest dSSTs exceed 6 K, affect 0.01% of the surface, and are seen in the Mediterranean, North and Irish Seas. There is an anti-correlation between the magnitude and the horizontal length scale of dSST events. Events wherein dSST exceeds 4 K have length scales of...
Tipo: Text
Ano: 2008
URL: http://archimer.ifremer.fr/doc/00004/11560/8156.pdf

SST spatial anisotropic covariances from METOP-AVHRR data
Provedor de dados: 5
Autores: Tandeo, Pierre; Autret, Emmanuelle; Chapron, Bertrand; Fablet, Ronan; Garello, Rene.
The Advanced Very High Resolution Radiometer (AVHRR) instrument on-board the METOP satellite is designed to provide very accurate measurements of Sea Surface Temperature (SST). In this work, using one year of METOP-AVHRR data and a geostatistical approach, we characterize the spatial anisotropy and non-stationarity of the SST variability using oriented ellipsoids. The method is also able to separate the true SST variability from the artificial error introduced by the METOP-AVHRR sensor. These spatial parameters are then used for producing variability atlases (available on-line) over the whole ocean.
Tipo: Text
Palavras-chave: SST; METOP-AVHRR; Spatial variability; Anisotropy.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00165/27586/25818.pdf

Quantifying Tidal Fluctuations in Remote Sensing Infrared SST Observations
Provedor de dados: 5
Autores: González-haro, Cristina; Ponte, Aurelien; Autret, Emmanuelle.
The expected amplitude of fixed-point sea surface temperature (SST) fluctuations induced by barotropic and baroclinic tidal flows is estimated from tidal current atlases and SST observations. The fluctuations considered are the result of the advection of pre-existing SST fronts by tidal currents. They are thus confined to front locations and exhibit fine-scale spatial structures. The amplitude of these tidally induced SST fluctuations is proportional to the scalar product of SST frontal gradients and tidal currents. Regional and global estimations of these expected amplitudes are presented. We predict barotropic tidal motions produce SST fluctuations that may reach amplitudes of 0.3 K. Baroclinic (internal) tides produce SST fluctuations that may reach...
Tipo: Text
Palavras-chave: Sea surface temperature; Satellite observations; Tidal currents; Internal tides.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00589/70075/68048.pdf

Linear Gaussian state-space model with irregular sampling: application to sea surface temperature
Provedor de dados: 5
Autores: Tandeo, Pierre; Ailliot, Pierre; Autret, Emmanuelle.
Satellites provide important information on many meteorological and oceanographic variables. State-space models are commonly used to analyse such data sets with measurement errors. In this work, we propose to extend the usual linear and Gaussian state-space to analyse time series with irregular time sampling, such as the one obtained when keeping all the satellite observations available at some specific location. We discuss the parameter estimation using a method of moment and the method of maximum likelihood. Simulation results indicate that the method of moment leads to a computationally efficient and numerically robust estimation procedure suitable for initializing the Expectation-Maximisation algorithm, which is combined with a standard numerical...
Tipo: Text
Palavras-chave: State-space model; Irregular sampling; Ornstein-Uhlenbeck process; EM algorithm; Sea surface temperature.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00039/15047/12441.pdf

A Multivariate Regression Approach to Adjust AATSR Sea Surface Temperature to In Situ Measurements
Provedor de dados: 5
Autores: Tandeo, Pierre; Autret, Emmanuelle; Piolle, Jean-francois; Tournadre, Jean; Ailliot, Pierre.
The Advanced Along-Track Scanning Radiometer (AATSR) onboard Envisat is designed to provide very accurate measurements of sea surface temperature (SST). Using colocated in situ drifting buoys, a dynamical matchup database (MDB) is used to assess the AATSR-derived SST products more precisely. SST biases are then computed. Currently, Medspiration AATSR SST biases are discrete values and can introduce artificial discontinuities in AATSR level-2 SST fields. The new AATSR SST biases presented in this letter are continuous. They are computed, for nighttime and best proximity confidence data, by linear regression with different MDB covariables (wind speed, latitude, aerosol optical depth, etc.). As found, the difference between dual-view and nadir-only SST...
Tipo: Text
Palavras-chave: Validation; Sea surface temperature (SST); Remote sensing; Advanced Along Track Scanning Radiometer (AATSR).
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6135.pdf

Use of the analysis system for monitoring the ARGO sensors drifts
Provedor de dados: 5
Autores: Autret, Emmanuelle; Gaillard, Fabienne.
In the previous letter, we briefly presented the analysis system operational at the Coriolis datacen-ter. This system both synthetises data sets by pro-ducing temperature and salinity gridded fields and checks for quality the data from the Coriolis data-base in real time. We will focus here on this latter application of the system. We will discuss of the use of the analysis tool to perform the real time and delayed mode quality control (QC), particularly of the ARGO profilers. Those two modes of QC are fundamentally different. Real time QC are meant to flag the data according to pre-defined quality levels, these tests must not slow down the data flow, they are therefore only qualitative. The delayed mode QC has to be quantitative, one wish to detect and...
Tipo: Text
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-6423.pdf

Animal-borne sensors successfully capture the real-time thermal properties of ocean basins
Provedor de dados: 5
Autores: Mcmahon, Cr; Autret, Emmanuelle; Houghton, Jdr; Lovell, P; Myers, Ae; Hays, Gc.
Climate change is perhaps the most pressing and urgent environmental issue facing the world today. However our ability to predict and quantify the consequences of this change is severely limited by the paucity of in situ oceanographic measurements. Marine animals equipped with sophisticated oceanographic data loggers to study their behavior offer one solution to this problem because marine animals range widely across the world's ocean basins and visit remote and often inaccessible locations. However, unlike the information being collected from conventional oceanographic sensing equipment, which has been validated, the data collected from instruments deployed on marine animals over long periods has not. This is the first long-term study to validate in situ...
Tipo: Text
Ano: 2005
URL: http://archimer.ifremer.fr/doc/00286/39727/38205.pdf

Statistical Descriptors of Ocean Regimes From the Geometric Regularity of SST Observations
Provedor de dados: 5
Autores: Ba, Sileye O.; Autret, Emmanuelle; Chapron, Bertrand; Fablet, Ronan.
In this letter, we evaluate to which extent the activity of ocean fronts can be retrieved from the geometric regularity of ocean tracer observations. Applied to sea surface temperature (SST), we propose a method for the characterization of this geometric regularity from curvature-based statistics along temperature level lines in front regions. To assess the effectiveness of the proposed descriptors, we used six years (from 2003 to 2008) of daily SST observations of the regions of Agulhas in the South of Africa and of Malvinas off the southern Brazilian coast. These experiments stress the relevance of geometric regularity features of tracer observation at ocean surface to characterize seasonal variations in ocean regimes.
Tipo: Text
Palavras-chave: Geosciences and remote sensing; Image analysis; Image classification; Image processing; Oceans; Ocean temperature; Sea surface.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00109/21993/20230.pdf

Group for High Resolution Sea Surface Temperature (GHRSST) analysis fields inter-comparisons-Part 2: Near real time web-based level 4 SST Quality Monitor (L4-SQUAM)
Provedor de dados: 5
Autores: Dash, Prasanjit; Ignatov, Alexander; Martin, Matthew; Donlon, Craig; Brasnett, Bruce; Reynolds, Richard W.; Banzon, Viva; Beggs, Helen; Cayula, Jean-francois; Chao, Yi; Grumbine, Robert; Maturi, Eileen; Harris, Andy; Mittaz, Jonathan; Sapper, John; Chin, Toshio M.; Vazquez-cuervo, Jorge; Armstrong, Edward M.; Gentemann, Chelle; Cummings, James; Piolle, Jean-francois; Autret, Emmanuelle; Roberts-jones, Jonah; Ishizaki, Shiro; Hoyer, Jacob L.; Poulter, Dave.
There are a growing number of level 4 (L4; gap-free gridded) sea surface temperature (SST) products generated by blending SST data from various sources which are available for use in a wide variety of operational and scientific applications. In most cases, each product has been developed for a specific user community with specific requirements guiding the design of the product. Consequently differences between products are implicit. In addition, anomalous atmospheric conditions, satellite operations and production anomalies may occur which can introduce additional differences. This paper describes a new web-based system called the L4 SST Quality Monitor (L4-SQUAM) developed to monitor the quality of L4 SST products. L4-SQUAM intercompares thirteen L4...
Tipo: Text
Palavras-chave: Sea surface temperature; Intercomparison; Climate data; Sea ice; Data centers.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00101/21188/19798.pdf

Multi-scale habitat preference analyses for Azorean blue whales
Provedor de dados: 5
Autores: Gonzalez Garcia, Laura; Pierce, Graham J.; Autret, Emmanuelle; Torres-palenzuela, Jesus M.
Blue whales are sighted every year around the Azores islands, which apparently provide an important seasonal foraging area. In this paper we aim to characterize habitat preferences and analyze the temporal distribution of blue whales around São Miguel Island. To do so, we applied Generalized Additive Models to an opportunistic cetacean occurrence dataset and remotely sensed environmental data on bathymetry, sea surface temperature, chlorophyll concentration and altimetry. We provide a brief description of the oceanography of the area, emphasizing its high spatio-temporal variability. In order to capture this dynamism, we used environmental data with two different spatial resolutions (low and high) and three different temporal resolutions (daily, weekly and...
Tipo: Text
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00460/57145/59069.pdf

Bay of Biscay’s temperature and salinity climatology : Bobyclim
Provedor de dados: 5
Autores: Vandermeirsch, Frederic; Charraudeau, Romain; Bonnat, Armel; Fichaut, Michele; Maillard, Catherine; Gaillard, Fabienne; Autret, Emmanuelle.
The Bay of Biscay climatology is the synthesis of all the in situ data collected in the bay of Biscay area as far as 15°W, in the 20th century and mainly by IFREMER, SHOM, and WDCA. It shows temperature and salinity monthly information through the whole water column with a 1/10 degree resolution. The resulting atlas was produced by an optimal analysis which can reflect different scales: shelf and abyssal plain. A fine scale on the coast reveals all the local effects, including plume and upwelling, and a large scale on the shelf where a slower signal is obtained due to the large scale circulation
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00029/14039/11232.pdf

Copernicus Marine Service Ocean State Report
Provedor de dados: 5
Autores: Von Schuckmann, Karina; Le Traon, Pierre-yves; Smith, Neville; Pascual, Ananda; Brasseur, Pierre; Fennel, Katja; Djavidnia, Samy; Aaboe, Signe; Alvarez Fanjul, Enrique; Autret, Emmanuelle; Axell, Lars; Aznar, Roland; Benincasa, Mario; Bentamy, Abderrahim; Boberg, Fredrik; Bourdalle-badie, Romain; Nardelli, Bruno Buongiorno; Brando, Vittorio E.; Bricaud, Clement; Breivik, Lars-anders; Brewin, Robert J. W.; Capet, Arthur; Ceschin, Adrien; Ciliberti, Stefania; Cossarini, Gianpiero; De Alfonso, Marta; De Pascual Collar, Alvaro; De Kloe, Jos; Deshayes, Julie; Desportes, Charles; Drevillon, Marie; Drillet, Yann; Droghei, Riccardo; Dubois, Clotilde; Embury, Owen; Etienne, Helene; Fratianni, Claudia; Garcia Lafuente, Jesus; Garcia Sotillo, Marcos; Garric, Gilles; Gasparin, Florent; Gerin, Riccardo; Good, Simon; Gourrion, Jerome; Gregoire, Marilaure; Greiner, Eric; Guinehut, Stephanie; Gutknecht, Elodie; Hernandez, Fabrice; Hernandez, Olga; Hoyer, Jacob; Jackson, Laura; Jandt, Simon; Josey, Simon; Juza, Melanie; Kennedy, John; Kokkini, Zoi; Korres, Gerasimos; Kouts, Mariliis; Lagemaa, Priidik; Lavergne, Thomas; Le Cann, Bernard; Legeais, Jean-francois; Lemieux-dudon, Benedicte; Levier, Bruno; Lien, Vidar; Maljutenko, Ilja; Manzano, Fernando; Marcos, Marta; Marinova, Veselka; Masina, Simona; Mauri, Elena; Mayer, Michael; Melet, Angelique; Melin, Frederic; Meyssignac, Benoit; Monier, Maeva; Muller, Malte; Mulet, Sandrine; Naranjo, Cristina; Notarstefano, Giulio; Paulmier, Aurelien; Perez Gomez, Begona; Perez Gonzalez, Irene; Peneva, Elisaveta; Perruche, Coralie; Peterson, K. Andrew; Pinardi, Nadia; Pisano, Andrea; Pardo, Silvia; Poulain, Pierre-marie; Raj, Roshin P.; Raudsepp, Urmas; Ravdas, Michaelis; Reid, Rebecca; Rio, Marie-hélène; Salon, Stefano; Samuelsen, Annette; Sammartino, Michela; Sammartino, Simone; Sando, Anne Britt; Santoleri, Rosalia; Sathyendranath, Shubha; She, Jun; Simoncelli, Simona; Solidoro, Cosimo; Stoffelen, Ad; Storto, Andrea; Szerkely, Tanguy; Tamm, Susanne; Tietsche, Steffen; Tinker, Jonathan; Tintore, Joaquin; Trindade, Ana; Van Zanten, Daphne; Vandenbulcke, Luc; Verhoef, Anton; Verbrugge, Nathalie; Viktorsson, Lena; Wakelin, Sarah L.; Zacharioudaki, Anna; Zuo, Hao.
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00601/71276/71010.pdf

The surface thermal signature and air-sea coupling over the Agulhas rings propagating in the South Atlantic Ocean interior
Provedor de dados: 5
Autores: Souza, J. M. A. C.; Chapron, Bertrand; Autret, Emmanuelle.
The surface signature of Agulhas rings propagating across the South Atlantic Ocean is observed based on three independent data sets: Advanced Microwave Scanning Radiometer for the Earth Observing System/Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) (TMI/AMSR-E) satellite sea surface temperature, Argo profiling floats and a merged winds product derived from scatterometer observations and reanalysis results. A persistent pattern of cold (negative) sea surface temperature (SST) anomalies in the eddy core, with warm (positive) anomalies at the boundary, is revealed. This pattern contrasts with the classical idea of a warm core anticyclone. Taking advantage of a moving reference frame corresponding to the altimetry-detected Agulhas rings,...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00208/31893/30318.pdf