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Registros recuperados: 69
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A Multiparametric Nonlinear Regression Approach for the Estimation of Global Surface Ocean pCO(2) Using Satellite Oceanographic Data ArchiMer
Krishna, Kande Vamsi; Shanmugam, Palanisamy; Nagamani, Pullaiahgari Venkata.
Estimation of the partial pressure of carbon dioxide (pCO(2)) and its space-time variability in global surface ocean waters is essential for understanding the carbon cycle and predicting the future atmospheric CO2 concentration. Until recently, only basin-scale distribution of pCO(2) has been reported by using satellite-derived climatological data due to the lack of models for global-scale applications. In the present work, a multiparametric nonlinear regression (MPNR) for the estimation of global-scale distribution of pCO(2) on the ocean surface is developed using continuous in-situ measurements of pCO(2), chlorophyll-a (Chla) concentration, sea surface temperature (SST), and sea surface salinity (SSS) obtained on a number of cruise programs in various...
Tipo: Text Palavras-chave: Carbon dioxide; Chlorophyll-a; Multiparametric algorithm; Partial pressure of carbon dioxide; Satellite oceanography; Sea surface salinity; Sea surface temperature.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00676/78842/81152.pdf
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AN INTERACTIVE SOFTWARE PACKAGE FOR VALIDATING SATELLITE DATA Gayana
Muraleedharan,P.M.; Pankajakshan,T..
Earth observation satellite launched in the last three decades have made vital contributions to the understanding of the planet. The earth system consisting of land, oceans and atmosphere is linked together by a number of complicated processes. Potential of microwave sensors in studying the boundary layer dynamics of the ocean-atmosphere system is well documented. Technology has revolutionized the application of such sensors and several missions are planned to take off in near future for meeting specific objectives. Launching of such sensors need to be followed by an extensive validation campaign for providing accurate and reliable information to the users. A PC-based interactive system has been developed and presented here for validating satellite mounted...
Tipo: Journal article Palavras-chave: Validation; Microwave sensor; Autocorrelation; Sea surface temperature; Wind speed; Columnar water vapor.
Ano: 2004 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382004000300018
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Analyse de la variation de la température de surface de la mer (SST) aux stations côtières de Côte d'Ivoire. OceanDocs
Mahan, N. Claude; Bamba, S. Barthélémy; Aman, Angora.
Depuis 1977, le Centre de Recherches Océanologiques (CRO) a entrepris des mesures quotidiennes de température de la mer le long des côtes ivoiriennes. Les remontées d'eaux froides qui affectent la côte ivoirienne présentent une forte variabilité à différentes échelles de temps et d'espace. Ces processus environnementaux complexes, irréguliers et difficiles à appréhender ont une grande influence sur un écosystème pélagique instable et par nature changeant (Arfi et al., 1995). Ces mesures répondent à un double objectif concernant l'étude saisonnière de l'upwelling côtier ivoiro-ghanéen pour prévoir les périodes et les zones favorables à la pêche sur le plateau continental ivoirien et à l'alimentation du projet GOOS (Global Ocean Observing System) de la...
Tipo: Journal Contribution Palavras-chave: Sea surface temperature; Sea level variations; Inshore stations.
Ano: 2008 URL: http://hdl.handle.net/1834/5748
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Association between bluefin tuna schools and oceanic features in the western Mediterranean ArchiMer
Royer, Francois; Fromentin, Jean-marc; Gaspar, P.
We present an analysis of the distribution of bluefin tuna Thunnus thynnus schools spotted during aerial surveys in the Gulf of Lions, in relation to oceanographic features. Bio-optical and thermal properties of the sea surface derived from high-resolution sensors (AVHRR and SeaWiFS) were studied on a daily basis, and an edge-detection technique was applied to detect frontal zones. Geostatistics and point-process analyses were used to evaluate the role of the environment in structuring the spatial pattern of bluefin tuna (BFT). The distribution of schools spotted was strongly non-stationary both in space and time; this is believed to be an effect of the survey design (transect sampling) and the influence of transient oceanographic structures (surface...
Tipo: Text Palavras-chave: Thunnus thynnus; Gulf of Lions; Point process analysis; Front detection; Sea surface temperature; Ocean colour; Aggregation.
Ano: 2004 URL: http://archimer.ifremer.fr/doc/00000/10786/7585.pdf
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Association of Sea Surface Temperature and the abundance of the Brown Booby (Sula leucogaster) according to the state of development in the Gorgona National Natural Park Boletín de Investigaciones
Perlaza-Gamboa,Alejandro; Giraldo,Alan; Payán,Luis Fernando; Estela,Felipe A..
ABSTRACT Variation in the physicochemical conditions of the sea can influence the distribution and abundance of seabirds by affecting the trophic structure of the pelagic environment. For this reason, we aimed to evaluate the association between the abundance of three developmental stages (chicks, juveniles, and adults) of the Brown Booby (Sula leucogaster etesiaca) and the sea surface temperature (SST) and its thermal anomaly (ANOM) in Gorgona Island, Colombian Pacific. These trends were assessed by performing cross-correlations and generalized linear models. Each developmental stage showed a different abundance tendence linked to SST and ANOM variation. It is suggested that these trends are due to the fact that increased sea temperature may be associated...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Time delay; Prey; Brown Bobby; Survival; Sea surface temperature.
Ano: 2020 URL: http://www.scielo.org.co/scielo.php?script=sci_arttext&pid=S0122-97612020000300031
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Atmospheric response to sea surface temperature mesoscale structures ArchiMer
Lambaerts, J.; Lapeyre, Guillaume; Plougonven, R.; Klein, Patrice.
Recent studies have revealed that strong sea surface temperature (SST) fronts, on the scale of a Western Boundary Current, significantly affect not just the Marine Boundary Layer but the entire troposphere. This has aroused renewed interest in air-sea interactions. The present study investigates the atmospheric response to fixed SST anomalies associated with mesoscale oceanic eddies and submesoscale filaments, using idealized simulations. Our main result is that in weak wind conditions, the vertical velocity in the planetary boundary layer (PBL) is linearly proportional to the SST Laplacian. This is established by a quantitative analysis in the spatial space as well as in the spectral space. Comparing the responses to two different SST fields shows that...
Tipo: Text Palavras-chave: Air-sea interactions; Boundary layer; Sea surface temperature.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00169/28047/26247.pdf
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Biomarker evidence of relatively stable community structure in the northern South China Sea during the last glacial and Holocene ArchiMer
He, Juan; Zhao, Meixun; Li, Li; Wang, Hui; Wang, Pinxian.
High-resolution molecular abundance records for several marine biomarkers during the last glacial and Holocene have been generated for core MD05-2904 (19 degrees 27.32'N, 116 degrees 15.15'E, 2066 in water depth) from the northern South China Sea. The U-37(K') SST record indicates a 4.4 degrees C cooling during the Last Glacial Maximum for this site, consistent with previous reconstructions. The contents Of C-37 alkenones, dinosterol, brassicasterol, and C-30 alkyl diols are used as productivity proxies for haptophytes, dinoflagellates, diatoms, and eustigmatophytes, respectively. These records reveal that both individual phytoplankton group and total productivity increased by several factors during the LGM compared with those for the Holocene, in response...
Tipo: Text Palavras-chave: Biomarkers; Paleo-productivity; Community structure; Sea surface temperature; South China Sea.
Ano: 2008 URL: https://archimer.ifremer.fr/doc/00207/31845/30258.pdf
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Causes of Low Frequency North Atlantic SST Variability in a Coupled GCM OceanDocs
Schneider, E.K.; Kirtman, B.P.; Wu, Z..
The low frequency sea surface temperature (SST) variability in the North Atlantic is studied using the Center for Ocean-Land-Atmosphere Studies (COLA) anomaly coupled general circulation model. The main focus is placed on the relative roles of stable and unstable coupled feedbacks in inducing the low frequency SST variability in various regions of the North Atlantic. To examine this question, a recently developed coupling technique, interactive ensembles, is applied to reduce the strength of “weather noise” in the model and isolate the atmospheric feedback to boundary forcing.
Tipo: Journal Contribution Palavras-chave: Sea surface temperature.
Ano: 2004 URL: http://hdl.handle.net/1834/508
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Characterizing and Comparing the Spawning Habitats of Sardine (Sardinops sagax) and Anchovy (Engraulis encrasicolus) in the Northern Benguela Region OceanDocs
Tjizoo,Mbeurora Beau.
Spawning habitats of sardine and anchovy in eastern boundary current systems are characterized in an attempt to understand the fluctuations observed in their abundance. The northern Benguela, as an eastern boundary current system, is characterized by turbulent conditions that seem to govern the variability observed in the abundance of these species. Sardine and anchovy have developed mechanisms that enable them to maximize productivity. In the northern Benguela, spawning intensity is historically known to be high in periods and vicinities where turbulence is reduced. However, it is believed that selection of conditions for spawning by these species may change withfluctuations in abundance of fish.
Tipo: Theses and Dissertations Palavras-chave: Sardine fisheries; Spawning; Anchovy fisheries; Habitat; Ecosystems; Sea surface temperature; Salinity; Spatial distribution; Climatic changes; Anthropogenic factors; Pelagic environment; Circulation; Coastlines.
Ano: 2008 URL: http://hdl.handle.net/1834/5231
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Comparison of organic (U-37(K)', TEX86H, LDI) and faunal proxies (foraminiferal assemblages) for reconstruction of late Quaternary sea surface temperature variability from offshore southeastern Australia ArchiMer
Lopes Dos Santos, Raquel A.; Spooner, Michelle I.; Barrows, Timothy T.; De Deckker, Patrick; Damste, Jaap S. Sinninghe; Schouten, Stefan.
Several proxies have been developed to reconstruct past sea surface temperature (SST), but different proxies may reflect temperatures of different seasons and each proxy is characterized by certain uncertainties. Therefore, a multiproxy approach is preferred to precisely reconstruct SST. Here, we reconstruct SST of the ocean offshore southeastern Australia (Murray Canyons area) for the last ~135 ka using three independent organic proxies (TEXH86 based on glycerol dialkyl glycerol tetraethers (GDGTs), UK'37 based on alkenones, and LDI based on long-chain diols) in addition to foraminiferal faunal assemblages. The organic proxy records show similar trends, with the highest temperature (21°C for UK'37 and TEXH86, and 25°C for LDI) during the last interglacial...
Tipo: Text Palavras-chave: Sea surface temperature; LDI index; TEX86H index; U-37(K') index; Foraminiferal assemblages; SE Australia.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00246/35763/34274.pdf
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Deglacial-Holocene environmental changes at the Pacific entrance of the Strait of Magellan ArchiMer
Harada, Naomi; Ninnemann, Ulysses; Lange, Carina B.; Marchant, Margarita E.; Sato, Miyako; Ahagon, Naokazu; Pantoja, Silvio.
We show environmental and nitrogen cycle changes between 13 and 2.5 kyr BP (from the latest deglaciation to the Holocene) based on biogeochemical records in a sediment core from the Pacific entrance of the Strait of Magellan. Organic carbon, total nitrogen, and C-37 alkenone contents were low during 13-9 kyr BP but increased rapidly at 8 kyr BP. The relative contribution of tetra-unsaturated C-37 alkenone, used as a salinity proxy, suggests low salinity during 13-9 kyr BP changing to high salinity at 8 kyr BP. Planktic foraminifer data showed that Globigerina bulloides was more abundant during the deglacial-early Holocene than in the mid-late Holocene, whereas abundances of Neogloboquadrina pachyderma showed the opposite pattern. This evidence plus...
Tipo: Text Palavras-chave: Biogenic components; Delta C-13; Delta N-15; Planktic foraminifera; Alkenone; Sea surface temperature; Southern Patagonia.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00264/37548/36825.pdf
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Detection of mesoscale thermal fronts from 4km data using smoothing techniques: Gradient-based fronts classification and basin scale application ArchiMer
Roa Pascuali, Liliana; Demarcq, Herve; Nieblas, Anne-elise.
In order to optimize frontal detection in sea surface temperature fields at 4 km resolution, a combined statistical and expert-based approach is applied to test different spatial smoothing of the data prior to the detection process. Fronts are usually detected at 1 km resolution using the histogram-based, single image edge detection (SIED) algorithm developed by Cayula and Cornillon in 1992, with a standard preliminary smoothing using a median filter and a 3 × 3 pixel kernel. Here, detections are performed in three study regions (off Morocco, the Mozambique Channel, and north-western Australia) and across the Indian Ocean basin using the combination of multiple windows (CMW) method developed by Nieto, Demarcq and McClatchie in 2012 which improves on the...
Tipo: Text Palavras-chave: Mesoscale thermal fronts; Preliminary smoothing; Sea surface temperature; 4 km resolution; Gradient intensity classification; Expert-based approach; Detection efficiency; Indian Ocean.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00269/37998/42023.pdf
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Determining bluefin tuna habitat through frontal features in the Mediterranean sea ArchiMer
Royer, Francois; Fromentin, Jean-marc; Farrugio, Henri; Gaspar, Philippe.
The distribution patterns of bluefin tuna schools observed during the STROMBOLI EU project (2000-2002) were analysed in relation to oceanographic conditions. High-resolution radiometers (AVHRR and SeaWiFS) were used on a daily basis to derive maps of environmental variability. An edge detection technique was especially applied to estimate the position of frontal features. Using a variety of geostatistical and point process techniques, we were able to show that the distribution of bluefin schools was partially driven by the occurrence of transient fronts in the Gulf of Lions. This is believed to be mainly a trophic association, since enhanced convergence and retention processes occur at fronts, possibly leading to higher prey densities (e.g. anchovies). The...
Tipo: Text Palavras-chave: Thunnus thynnus; Aerial survey; Gulf of Lions; Sea surface temperature; Ocean colour; Fronts.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/00194/30504/28914.pdf
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Diagnosis of high-resolution upper ocean dynamics from noisy sea surface temperatures ArchiMer
Isern-fontanet, J.; Hascoet, Erwan.
The noise present in infrared satellite measurements of sea surface temperature (SST) hampers the use of surface quasi-geostrophic (SQG) equations to diagnose ocean dynamics at high resolutions. Here we propose a methodology to reduce the contribution of noise when diagnosing surface vorticity, divergence, and vertical velocity from SST able to retain the dynamics at scales of a few kilometers. It is based on the use of denoising techniques with curvelets as basis functions and the application of a selective low-pass filters to improve the reconstruction of surface upwelling/downwelling patterns. First, it is tested using direct numerical simulations of SQG turbulence and then applied to diagnose low-frequency vertical velocity patterns from real MODIS...
Tipo: Text Palavras-chave: Sea surface temperature; Surface quasi-geostrophy; Remote sensing; Vertical velocity; Ocean submesoscales; Image denoising.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00170/28162/26391.pdf
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Effect of subjective choices on the objective analysis of sea surface temperature data in the tropical Atlantic and Pacific oceans ArchiMer
Molinari, Rl; Festa, Jf.
Many subjective choices are required to perform an objective interpolation (OI) analysis of environmental variables. Herein, we consider the effects on the statistical analysis of sea surface temperature (SST) using (1) a structure function or covariance analysis, (2) different analytical expressions to represent the statistics of the raw data, and (3) different historical SST data sets. The historical data sets are the well-sampled Comprehensive Ocean-Atmospheric Data Set (COADS) and the poorly sampled historical expendable bathythermograph (XBT) data set. Results from these analyses are used to generate error maps for a poorly-sampled, two month XBT array and a proposed well-sampled profiling float array. For the relatively data-rich GOADS analysis,...
Tipo: Text Palavras-chave: Analyse objective; Température superficielle; Fonction de structure; Analyse statistique; Interpolation objective; Objective analysis; Sea surface temperature; Structure function; Statistical analysis; Objective interpolation.
Ano: 2000 URL: http://archimer.ifremer.fr/doc/00325/43573/44041.pdf
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Environmental noise in spawning areas: the case of Atlantic bluefin tuna (Thunnus thynnus) ArchiMer
Royer, Francois; Fromentin, Jean-marc.
This paper provides an exploratory analysis aiming to seek whether the colour of environmental noise theory could help in understanding the intriguing reproductive strategy of Atlantic bluefin tuna (BFT). A frequency-based approach based on spectral exponents, f(beta) with beta < 0, is chosen and applied on 10 biogeographical provinces covering the North Atlantic. The major BFT spawning area, i.e. the Mediterranean Sea, was the only one to display a pink power spectrum, whereas open ocean regions displayed more reddened fluctuations, i.e. greater variance at low frequencies. Environmental noise in the Mediterranean could, thus, offer more favourable characteristics on the long-term than the open ocean. The implications of these findings are discussed in...
Tipo: Text Palavras-chave: Thunnus thynnus; Spectral analysis; Spawning; Sea surface temperature; Environmental noise.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2437.pdf
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Exploring Machine Learning to Correct Satellite-Derived Sea Surface Temperatures ArchiMer
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
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Freshwater influx, hydrographic reorganization and the dispersal of ice-rafted detritus in the sub-polar North Atlantic Ocean during the last deglaciation ArchiMer
Small, David; Austin, William; Rinterknecht, Vincent.
A sediment core from the north-east North Atlantic contains high-resolution co-registered foraminiferal O-18 and ice-rafted detritus (IRD) records for the last deglaciation. These reveal a distinct ice-rafting event that occurred at the time of Greenland Interstade 1d (GI-1d), a feature also seen in other high-resolution cores from the North Atlantic. The occurrence of a geographically widespread peak in IRD at ice distal sites at a time when increased freshwater flux to the surface ocean is inferred to have caused rapid cooling suggests a mechanistic link between the processes, analogous to the Younger Dryas (GS-1) cooling episode. The general absence of IRD at southern locations at other times during GI-1 when the flux of icebergs from surviving ice...
Tipo: Text Palavras-chave: Deglaciation; Hydrography; Ice-rafted detritus; North Atlantic; Sea surface temperature.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00291/40180/39238.pdf
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Glacial cooling as inferred from marine temperature proxies TEX86H and U-37(K ') ArchiMer
Ho, Sze Ling; Laepple, Thomas.
Knowledge of the magnitude of the Last Glacial Maximum (LGM) cooling is a useful constraint for estimating the climate sensitivity used in projecting future climate change. Proxy comparison, especially that between the alkenone-based U-37(K ') and the archaeal tetraether-based TEX86, has been increasingly applied in paleoceanographic studies as a measure to better constrain proxy-derived temperature estimates. In this study, we compile and compare published multiproxy (U-37(K ') and TEX86H) records of glacial cooling measured on the same sediment cores. In spite of the diversity in oceanographic and sedimentation settings spanned by the study sites, we find that the TEX86H-derived mean tropical LGM cooling is approximately twice as strong as that suggested...
Tipo: Text Palavras-chave: Last Glacial Maximum; Sea surface temperature; Multiproxy; PMIP3; U-37(K '); TEX86H.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00352/46297/45933.pdf
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Global Patterns of Submesoscale Surface Salinity Variability ArchiMer
Drushka, Kyla; Asher, William E.; Sprintall, Janet; Gille, Sarah T.; Hoang, Clifford.
Surface salinity variability on O(1-10) km lateral scales (the submesoscale) generates density variability and thus has implications for submesoscale dynamics. Satellite salinity measurements represent a spatial average over horizontal scales of approximately 40-100 km but are compared to point measurements for validation, so submesoscale salinity variability also complicates validation of satellite salinities. Here, we combine several databases of historical thermosalinograph (TSG) measurements made from ships to globally characterize surface submesoscale salinity, temperature, and density variability. In river plumes; regions affected by ice melt or upwelling; and the Gulf Stream, South Atlantic, and Agulhas Currents, submesoscale surface salinity...
Tipo: Text Palavras-chave: Small scale processes; Freshwater; Fronts; Sea surface temperature; Oceanic variability.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00676/78805/81042.pdf
Registros recuperados: 69
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