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| Registros recuperados: 25 | |
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| Akhil, V. P.; Durand, Fabien; Lengaigne, Matthieu; Vialard, Jerome; Keerthi, M. G.; Gopalakrishna, V. V.; Deltel, Charles; Papa, Fabrice; De Boyer Montegut, Clement. |
| In response to the Indian Monsoon freshwater forcing, the Bay of Bengal exhibits a very strong seasonal cycle in sea surface salinity (SSS), especially near the mouths of the Ganges-Brahmaputra and along the east coast of India. In this paper, we use an eddy-permitting (∼25 km resolution) regional ocean general circulation model simulation to quantify the processes responsible for this SSS seasonal cycle. Despite the absence of relaxation toward observations, the model reproduces the main features of the observed SSS seasonal cycle, with freshest water in the northeastern Bay, particularly during and after the monsoon. The model also displays an intense and shallow freshening signal in a narrow (∼100 km wide) strip that hugs the east coast of India, from... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00197/30819/29189.pdf |
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| Akhil, V. P.; Lengaigne, Matthieu; Durand, Fabien; Vialard, Jerome; Chaitanya, A. V. S.; Keerthi, M. G.; Gopalakrishna, V. V.; Boutin, Jacqueline; De Boyer Montegut, Clement. |
| The Bay of Bengal (BoB) exhibits a wide range of sea surface salinity (SSS), with very fresh water induced by heavy monsoonal precipitation and river run-offs to the north, and saltier water to the south. This is a particularly challenging region for the application of satellite-derived SSS measurements because of the potential pollution of the SSS signal by radio frequency interference (RFI) and land-induced contamination in this semi-enclosed basin. The present study validates recent level-3 monthly gridded (1° × 1°) SSS products from Soil Moisture and Ocean Salinity (SMOS) and Aquarius missions to an exhaustive in situ SSS product for the BoB. Current SMOS SSS retrievals do not perform better than existing climatologies. This is in stark contrast to... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00319/42986/45003.pdf |
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| Vialard, Jerome; Duvel, J. P.; Mcphaden, M. J.; Bouruet-aubertot, P.; Ward, Ben; Key, E.; Bourras, D.; Weller, Robert; Minnett, P.; Weill, A.; Cassou, C.; Eymard, L.; Fristedt, T.; Basdevant, C.; Dandonneau, Y.; Duteil, O.; Izumo, T.; De Boyer Montegut, Clement; Masson, S.; Marsac, F.; Menkes, C.; Kennan, S.. |
| A field experiment in the southwestern Indian Ocean provides new insights into ocean-atmosphere interactions in a key climatic region. |
| Tipo: Text |
Palavras-chave: Madden julian oscillation; Southwest indian ocean; Surface temperature; Mixed layer; Intraseasonal variability; Rainfall variability; Tropical cyclones; Western pacific; Dipole mode; El nino. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00185/29634/27990.pdf |
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| Menkes, Christophe E.; Lengaigne, Matthieu; Levy, Marina; Ethe, Christian; Bopp, Laurent; Aumont, Olivier; Vincent, Emmanuel; Vialard, Jerome; Jullien, Swen. |
| In this paper, we explore the global responses of surface temperature, chlorophyll and primary production to tropical cyclones (TCs). Those ocean responses are first characterized from the statistical analysis of satellite data under ~1000 TCs over the 1998-2007 period. Besides the cold wake, the vast majority of TCs induce a weak chlorophyll response, with only ~10% of induced blooms exceeding 0.1 mg.m-3. The largest chlorophyll responses mostly occur within coastal regions, in contrast to the strongest cold wakes that generally occur farther offshore. To understand this decoupling, we analyze a coupled dynamical-biogeochemical oceanic simulation forced by realistic wind vortices applied along observed TC tracks. The simulation displays a realistic... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00333/44449/44121.pdf |
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| Masson, S; Luo, Jj; Madec, G; Vialard, Jerome; Durand, F; Gualdi, S; Guilyardi, E; Behera, S; Delecluse, P; Navarra, A; Yamagata, T. |
| In the present study, we use a coupled model to evaluate the effect of shallow salinity stratification on the sea surface temperature (SST) and on the monsoon onset in the southeastern Arabian Sea (SEAS). A 100-year control experiment shows that the coupled model reproduces the main climatic features in this region in terms of SST, precipitation and barrier layer (BL). A 100-year sensitivity experiment (where BL effects have been suppressed in the SEAS) shows that BL enhances the spring SST warming by 0.5 degrees C, and leads to a statistically significant increase of precipitation in May (3 mm/day) linked to an early (10 to 15 days) monsoon onset. This suggests that the BL extent may be a useful predictor of the summer monsoon onset in the area with a... |
| Tipo: Text |
Palavras-chave: Summer monsoon season; Surface temperature; Indian ocean; Mixed layer; Northeast monsoon; Southwest monsoon; Onset vortex; Coupled GCM; Mechanisms; Evolution. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00203/31422/29819.pdf |
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| Currie, J. C.; Lengaigne, M.; Vialard, Jerome; Kaplan, David; Aumont, Olivier; Naqvi, S. W. A.; Maury, Olivier. |
| The Indian Ocean Dipole (IOD) and the El Nino/Southern Oscillation (ENSO) are independent climate modes, which frequently co-occur, driving significant interannual changes within the Indian Ocean. We use a four-decade hindcast from a coupled biophysical ocean general circulation model, to disentangle patterns of chlorophyll anomalies driven by these two climate modes. Comparisons with remotely sensed records show that the simulation competently reproduces the chlorophyll seasonal cycle, as well as open-ocean anomalies during the 1997/1998 ENSO and IOD event. Results suggest that anomalous surface and euphotic-layer chlorophyll blooms in the eastern equatorial Indian Ocean in fall, and southern Bay of Bengal in winter, are primarily related to IOD forcing.... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00166/27749/25945.pdf |
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| Izumo, Takeshi; Vialard, Jerome; Lengaigne, Matthieu; De Boyer Montegut, Clement; Behera, Swadhin K.; Luo, Jing-jia; Cravatte, Sophie; Masson, Sebastien; Yamagata, Toshio. |
| El Nino-Southern Oscillation (ENSO) consists of irregular episodes of warm El Nino and cold La Nina conditions in the tropical Pacific Ocean(1), with significant global socio-economic and environmental impacts(1). Nevertheless, forecasting ENSO at lead times longer than a few months remains a challenge(2,3). Like the Pacific Ocean, the Indian Ocean also shows interannual climate fluctuations, which are known as the Indian Ocean Dipole(4,5). Positive phases of the Indian Ocean Dipole tend to co-occur with El Nino, and negative phases with La Nina(6-9). Here we show using a simple forecast model that in addition to this link, a negative phase of the Indian Ocean Dipole anomaly is an efficient predictor of El Nino 14 months before its peak, and similarly, a... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00002/11304/7831.pdf |
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| Vialard, Jerome; Shenoi, S. S. C.; Mccreary, J. P.; Shankar, D.; Durand, F.; Fernando, V.; Shetye, S. R.. |
| A new observational record of upper-ocean currents at 15 degrees N on the western coast of India is dominated by intraseasonal (55 - 110 day) variations of alongshore currents, whereas sea level at the same location has a clear seasonal signal. These observations can be interpreted within the framework of linear wave theory. At 15 degrees N, the minimum period for planetary waves is similar to 90 day, meaning that intraseasonal energy is largely trapped at the coast in the form of poleward-propagating Kelvin waves, while lower-frequency signals associated with the annual cycle can radiate offshore as planetary waves. This dynamical difference results in a steeper offshore slope of sea level at intraseasonal timescale, and thus stronger geostrophic... |
| Tipo: Text |
Palavras-chave: Variability; Dynamics; Circulation; Currents. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00185/29631/27993.pdf |
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| Izumo, Takeshi; Masson, Sebastien; Vialard, Jerome; De Boyer Montegut, Clement; Behera, Swadhin K.; Madec, Gurvan; Takahashi, Keiko; Yamagata, Toshio. |
| The Madden-Julian oscillation (MJO) is the main component of intraseasonal variability of the tropical convection, with clear climatic impacts at an almost-global scale. Based on satellite observations, it is shown that there are two types of austral-summer MJO events (broadly defined as 30-120 days convective variability with eastward propagation of about 5 m/s). Equatorial MJO events have a period of 30-50 days and tend to be symmetric about the equator, whereas MJO events centered near 8A degrees S tend to have a longer period of 55-100 days. The lower-frequency variability is associated with a strong upper-ocean response, having a clear signature in both sea surface temperature and its diurnal cycle. These two MJO types have different interannual... |
| Tipo: Text |
Palavras-chave: Intraseasonal Madden-Julian oscillation (MJO); Seychelles-Chagos thermocline ridge/thermocline dome of the Indian Ocean; Indian Ocean dipole (IOD); El Nino southern oscillation (ENSO); Diurnal cycle; Oceanic diurnal warm layers; Air-sea interactions; Ocean-atmosphere coupling; Interannual variations; Mixed layer; Australian weather. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00013/12416/9221.pdf |
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| Mcphaden, Mj; Foltz, Jr; Lee, T.; Murty, V. S. N.; Ravichandran, Muthalagu; Vecchi, Ga; Vialard, Jerome; Wiggert, J.d.; Yu, L.. |
| Cyclone Nargis (Figure 1a) made landfall in Myanmar (formerly Burma) on 2 May 2008 with sustained winds of approximately 210 kilometers per hour, equivalent to a category 3–4 hurricane. In addition, Nargis brought approximately 600 millimeters of rain and a storm surge of 3–4 meters to the low-lying and densely populated Irrawaddy River delta. In its wake, the storm left an estimated 130,000 dead or missing and more than $10 billion in economic losses. It was the worst natural disaster to strike the Indian Ocean region since the 26 December 2004 tsunami and the worst recorded natural disaster ever to affect Myanmar. |
| Tipo: Text |
Palavras-chave: IndOOS; Bay of Bengal; Cyclone Nargis. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00185/29643/28009.pdf |
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| Stammer, Detlef; Bracco, Annalisa; Achutarao, Krishna; Beal, Lisa; Bindoff, Nathaniel L.; Braconnot, Pascale; Cai, Wenju; Chen, Dake; Collins, Matthew; Danabasoglu, Gokhan; Dewitte, Boris; Farneti, Riccardo; Fox-kemper, Baylor; Fyfe, John; Griffies, Stephen M.; Jayne, Steven R.; Lazar, Alban; Lengaigne, Matthieu; Lin, Xiaopei; Marsland, Simon; Minobe, Shoshiro; Monteiro, Pedro M. S.; Robinson, Walter; Roxy, Mathew Koll; Rykaczewski, Ryan R.; Speich, Sabrina; Smith, Inga J.; Solomon, Amy; Storto, Andrea; Takahashi, Ken; Toniazzo, Thomas; Vialard, Jerome. |
| Natural variability and change of the Earth's climate have significant global societal impacts. With its large heat and carbon capacity and relatively slow dynamics, the ocean plays an integral role in climate, and provides an important source of predictability at seasonal and longer timescales. In addition, the ocean provides the slowly evolving lower boundary to the atmosphere, driving, and modifying atmospheric weather. Understanding and monitoring ocean climate variability and change, to constrain and initialize models as well as identify model biases for improved climate hindcasting and prediction, requires a scale-sensitive, and long-term observing system. A climate observing system has requirements that significantly differ from, and sometimes are... |
| Tipo: Text |
Palavras-chave: Ocean observing system; Ocean climate; Earth observations; In situ measurements; Satellite observations; Ocean modeling; Climate information. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00675/78724/80996.pdf |
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| Keerthi, Madhavan Girijakumari; Lengaigne, Matthieu; Levy, Marina; Vialard, Jerome; Parvathi, Vallivattathillam; De Boyer Montegut, Clement; Ethe, Christian; Aumont, Olivier; Suresh, Iyyappan; Akhil, Valiya Parambil; Muraleedharan, Pillathu Moolayil. |
| The northern Arabian Sea hosts a winter chlorophyll bloom, triggered by convective overturning in response to cold and dry northeasterly monsoon winds. Previous studies of interannual variations of this bloom only relied on a couple of years of data and reached no consensus on the associated processes. The current study aims at identifying these processes using both similar to 10 years of observations (including remotely sensed chlorophyll data and physical parameters derived from Argo data) and a 20-year-long coupled biophysical ocean model simulation. Despite discrepancies in the estimated bloom amplitude, the six different remotely sensed chlorophyll products analysed in this study display a good phase agreement at seasonal and interannual timescales.... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00395/50625/51332.pdf |
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| Mcphaden, M. J.; Meyers, G.; Ando, K.; Masumoto, Y.; Murty, V. S. N.; Ravichandran, M.; Syamsudin, F.; Vialard, Jerome; Yu, L.; Yu, W.. |
| The Indian Ocean is unique among the three tropical ocean basins in that it is blocked at 25 degrees N by the Asian landmass. Seasonal heating and cooling of the land sets the stage for dramatic monsoon wind reversals, strong ocean atmosphere interactions, and intense seasonal rains over the Indian subcontinent, Southeast Asia, East Africa, and Australia. Recurrence of these monsoon rains is critical to agricultural production that supports a third of the world's population. The Indian Ocean also remotely influences the evolution of El Nino-Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), North American weather, and hurricane activity. Despite its importance in the regional and global climate system though, the Indian Ocean is the most... |
| Tipo: Text |
Palavras-chave: Madden julian oscillation; Tropical indian ocean; Sea heat fluxes; Intraseasonal variability; Equatorial currents; Summer monsoon; Interannual variability; Arabian sea; El nino; Rainfall variability. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00185/29632/27992.pdf |
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| Troccoli, Alberto; Balmaseda, Magdalena A.; Segschneider, Joachim; Vialard, Jerome; Anderson, David L. T.; Haines, Keith; Stockdale, Tim; Vitart, Frédéric; Fox, Alan D.. |
| This paper is an evaluation of the role of salinity in the framework of temperature data assimilation in a global ocean model that is used to initialize seasonal climate forecasts. It is shown that the univariate assimilation of temperature profiles, without attempting to correct salinity, can induce first-order errors in the subsurface temperature and salinity fields. A recently developed scheme by A. Troccoli and K. Haines is used to improve the salinity field. In this scheme, salinity increments are derived from the observed temperature, by using the model temperature and salinity profiles, assuming that the temperature-salinity relationship in the model profiles is preserved. In addition, the temperature and salinity fields are matched below the... |
| Tipo: Text |
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| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00251/36272/34839.pdf |
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| Registros recuperados: 25 | |
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