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| Registros recuperados: 12 | |
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| Wang, Chen; Mouche, Alexis; Tandeo, Pierre; Stopa, Justin; Longépé, Nicolas; Erhard, Guillaume; Foster, Ralph C.; Vandemark, Douglas; Chapron, Bertrand. |
| The Sentinel‐1 mission is part of the European Copernicus program aiming at providing observations for Land, Marine and Atmosphere Monitoring, Emergency Management, Security and Climate Change. It is a constellation of two (Sentinel‐1 A and B) Synthetic Aperture Radar (SAR) satellites. The SAR wave mode (WV) routinely collects high‐resolution SAR images of the ocean surface during day and night and through clouds. In this study, a subset of more than 37,000 SAR images is labelled corresponding to ten geophysical phenomena, including both oceanic and meteorologic features. These images cover the entire open ocean and are manually selected from Sentinel‐1A WV acquisitions in 2016. For each image, only one prevalent geophysical phenomenon with its prescribed... |
| Tipo: Text |
Palavras-chave: Manual labelling; Ocean surface phenomena; Sentinel-1 wave mode; Synthetic aperture radar. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00512/62406/66659.pdf |
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| Vandemark, Douglas; Edson, James B; Chapron, Bertrand. |
| Aircraft altimeter and in situ measurements are used to examine relationships between altimeter backscatter and the magnitude of near-surface wind and friction velocities. Comparison of altimeter radar cross section with wind speed is made through the modified Chelton-Wentz algorithm. Improved agreement is found after correcting 10-m winds for both surface current and atmospheric stability. An altimeter friction velocity algorithm is derived based on the wind speed model and an open-ocean drag coefficient. Close agreement between altimeter- and in situ-derived friction velocities is found. For this dataset, quality of the altimeter inversion to surface friction velocity is comparable to that for adjusted winds and clearly better than the inversion to true... |
| Tipo: Text |
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| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00336/44711/44902.pdf |
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| Nouguier, Frederic; Mouche, Alexis; Rascle, Nicolas; Chapron, Bertrand; Vandemark, Douglas. |
| Global colocalized ocean surface measurements using the Global Precipitation Measurement near-nadir dual-frequency Ku- and Ka-band microwave measurements are analyzed and compared. Focusing on the Ka and Ku cross-sections fall-off with incidence angles, the contemporaneous measurements enable to more precisely document differing ocean scattering characteristics for both microwave frequencies. Sensitivity with wind speed and significant wave height is further reported using global comparisons with numerical estimates. As demonstrated, the bifrequency capability can provide direct means to efficiently separate short-scale wave contributions, between mean squared slope and curvature characteristics, and to further gain valuable insights concerning near-nadir... |
| Tipo: Text |
Palavras-chave: Microwave; Radar cross section; Scattering; Spaceborne radar. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00352/46334/47128.pdf |
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| Elfouhaily, Tanos; Joelson, Maminirina; Guignard, Stéphan; Branger, Hubert; Thompson, Donald; Chapron, Bertrand; Vandemark, Douglas. |
| A generalization of the Woodward's theorem is applied to the case of random signals jointly modulated in amplitude and frequency. This yields the signal spectrum and a rather robust estimate of the bispectrum. Furthermore, higher order statistics that quantify the amount of energy in the signal due to nonlinearities, e.g., wave-wave interaction in the case of water waves, can be inferred. Considering laboratory wind generated water waves, comparisons between the presented generalization and more standard techniques allow to extract the spectral energy due to nonlinear wave-wave interactions. It is shown that our analysis extends the domain of standard spectral estimation techniques from narrow-band to broad-band processes. |
| Tipo: Text |
Palavras-chave: Frequency modulation; Amplitude modulation; Bispectrum; Vertical asymmetry; Horizontal asymmetry; Wave wave interaction; Mode coupling; Fluid mechanics; Modulation de fréquence; Modulation d'amplitude; Bispectre; Dissymétrie horisontale; Dissymétrie verticale; Interaction vague vague; Couplage de mode; Mécaniques des fluides. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/2003/publication-741.pdf |
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| Grodsky, Semyon A.; Reul, Nicolas; Bentamy, Abderrahim; Vandemark, Douglas; Guimbard, Sebastien. |
| One of the saltiest seas, the Mediterranean, experiences significant salinity variations in near surface layers. Satellite sea surface salinity (SSS) data obtained using Soil Moisture Active Passive (SMAP) mission indicate steady salinification of the eastern Mediterranean Levantine Basin at a rate of ~0.14 psu/year during 2015–2018. Satellite-observed salinity changes are confirmed by Argo float data and suggest possible changes in properties of the Levantine Intermediate Water. Eastern Mediterranean salinification often coincides with a freshening of the western Ionian Sea. Based on satellite altimetry geostrophic currents, these salinity changes are concurrent with a weakening cyclonic circulation in the Levantine Basin and strengthening anticyclonic... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00503/61430/65113.pdf |
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| Plagge, Amanda M.; Vandemark, Douglas; Chapron, Bertrand. |
| A 5-yr dataset collected over two surface current and meteorological moorings allows rigorous evaluation of questions surrounding wave current interaction and the scatterometer. Results demonstrate that scatterometer winds represent winds relative to the moving sea surface, affirming previous observational efforts that inferred the phenomenon using climatological approaches over larger time and space scales in equatorial and western boundary currents. Comparisons of wind residuals between Ku-band Quick Scatterometer (QuikSCAT) and buoy measurements show nearly one-to-one correlations with ocean surface velocity for 5-, 12.5-, and 25-km resolution wind speed products, especially under conditions of moderate wind speed and near-neutral atmospheric stability.... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00118/22896/20703.pdf |
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| Chen, Ge; Chapron, Bertrand; Tournadre, Jean; Katsaros, Kristina; Vandemark, Douglas. |
| The TOPEX/POSEIDON mission offers the first opportunity to observe rain cells over the ocean by a dual-frequency radar altimeter (TOPEX) and simultaneously observe their natural radiative properties by a three-frequency radiometer (TOPEX microwave radiometer (TMR)). This work is a feasibility study aimed at understanding the capability and potential of the active/passive TOPEX/TMR system for oceanic rainfall detection. On the basis of past experiences in rain flagging, a joint TOPEX/TMR rain probability index is proposed. This index integrates several advantages of the two sensors and provides a more reliable rain estimate than the radiometer alone. One year's TOPEX/TMR TMR data are used to test the performance of the index. The resulting rain frequency... |
| Tipo: Text |
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| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00336/44719/44883.pdf |
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| Salisbury, Joseph; Vandemark, Douglas; Joensson, Bror; Balch, William; Chakraborty, Sumit; Lohrenz, Steven; Chapron, Bertrand; Hales, Burke; Mannino, Antonio; Mathis, Jeremy T.; Reul, Nicolas; Signorini, Sergio R.; Wanninkhof, Rik; Yates, Kimberly K.. |
| Space-based observations offer unique capabilities for studying spatial and temporal dynamics of the upper ocean inorganic carbon cycle and, in turn, supporting research tied to ocean acidification (OA). Satellite sensors measuring sea surface temperature, color, salinity, wind, waves, currents, and sea level enable a fuller understanding of a range of physical, chemical, and biological phenomena that drive regional OA dynamics as well as the potentially varied impacts of carbon cycle change on a broad range of ecosystems. Here, we update and expand on previous work that addresses the benefits of space-based assets for OA and carbonate system studies. Carbonate chemistry and the key processes controlling surface ocean OA variability are reviewed. Synthesis... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00271/38234/36417.pdf |
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| Grodsky, Semyon A.; Reul, Nicolas; Vandemark, Douglas; Bentamy, Abderrahim. |
| The time variability of wind and rainfall in the Atlantic Intertropical Convergence Zone (ITCZ) has a wide oscillation spectrum that includes strong intra-month periodicities. These latter short-period oscillations span from individual convection lifecycle events of a few hours to longer pentad and multi-week convective cluster periods. This study reports on measured ITCZ rain variability at periods of a few weeks and its imprint on sea surface salinity (SSS) observed using satellite remote sensing. Despite small amplitude of variations of only 0.1−0.2 psu, these changes are shown to be detectable in radiometer SSS estimates collected by the Soil Moisture Active Passive (SMAP) satellite. They are shown to develop in the mid-Atlantic ITCZ latitude band and... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00509/62045/66197.pdf |
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| Land, Peter E.; Findlay, Helen S.; Shutler, Jamie D.; Ashton, Ian; Holding, Thomas; Grouazel, Antoine; Ardhuin, Fanny; Reul, Nicolas; Piolle, Jean-francois; Chapron, Bertrand; Quilfen, Yves; Bellerby, Richard G.j.; Bhadury, Punyasloke; Salisbury, Joseph; Vandemark, Douglas; Sabia, Roberto. |
| Improving our ability to monitor ocean carbonate chemistry has become a priority as the ocean continues to absorb carbon dioxide from the atmosphere. This long-term uptake is reducing the ocean pH; a process commonly known as ocean acidification. The use of satellite Earth Observation has not yet been thoroughly explored as an option for routinely observing surface ocean carbonate chemistry, although its potential has been highlighted. We demonstrate the suitability of using empirical algorithms to calculate total alkalinity (AT) and total dissolved inorganic carbon (CT), assessing the relative performance of satellite, interpolated in situ, and climatology datasets in reproducing the wider spatial patterns of these two variables. Both AT and CT in situ... |
| Tipo: Text |
Palavras-chave: Carbonate chemistry; Earth observation; Ocean acidification; Total alkalinity; Dissolved inorganic carbon; SMOS; Aquarius; CORA; HadGEM2-ES. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00591/70267/68368.pdf |
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| Land, Peter; Shutler, Jamie; Findlay, Helen; Girard Ardhuin, Fanny; Sabia, Roberto; Reul, Nicolas; Piolle, Jean-francois; Chapron, Bertrand; Quilfen, Yves; Salisbury, Joseph; Vandemark, Douglas; Bellerby, Richard; Bhadury, Punyasloke. |
| Approximately a quarter of the carbon dioxide (CO2) that we emit into the atmosphere is absorbed by the ocean. This oceanic uptake of CO2 leads to a change in marine carbonate chemistry resulting in a decrease of seawater pH and carbonate ion concentration, a process commonly called ‘Ocean Acidification’. Salinity data are key for assessing the marine carbonate system, and new space-based salinity measurements will enable the development of novel space-based ocean acidification assessment. Recent studies have highlighted the need to develop new in situ technology for monitoring ocean acidification, but the potential capabilities of space-based measurements remain largely untapped. Routine measurements from space can provide quasi-synoptic, reproducible... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00247/35863/34384.pdf |
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| Registros recuperados: 12 | |
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