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| Registros recuperados: 23 | |
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| Akhil, V. P.; Lengaigne, M.; Vialard, J.; Durand, F.; Keerthi, M. G.; Chaitanya, A. V. S.; Papa, F.; Gopalakrishna, V. V.; De Boyer Montegut, Clement. |
| Recent observational studies provided preliminary insights on the interannual variability of Bay of Bengal (BoB) Sea Surface Salinity (SSS), but are limited by the poor data coverage. Here, we describe the BoB interannual SSS variability and its driving processes from a regional eddy-permitting ocean general circulation model forced by interannually varying air-sea fluxes and altimeter-derived discharges of major rivers over the past two decades. Simulated interannual SSS variations compare favorably with both in situ and satellite data and are largest in boreal fall in three regions: the northern BoB, the coastal region off east India, and the Andaman Sea. In the northern BoB, these variations are independent from those in other regions and mostly driven... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00360/47134/47083.pdf |
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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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| Souza, Joao Marcos Azevedo Correia De; De Boyer Montegut, Clement; Le Traon, Pierre-yves. |
| Three methods for automatic detection of mesoscale coherent structures are applied to Sea Level Anomaly (SLA) fields in the South Atlantic. The first method is based on the wavelet packet decomposition of the SLA data, the second on the estimation of the Okubo-Weiss parameter and the third on a geometric criterion using the winding-angle approach. The results provide a comprehensive picture of the mesoscale eddies over the South Atlantic Ocean, emphasizing their main characteristics: amplitude, diameter, duration and propagation velocity. Five areas of particular eddy dynamics were selected: the Brazil Current, the Agulhas eddies propagation corridor, the Agulhas Current retroflexion, the Brazil-Malvinas confluence zone and the northern branch of the... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00039/15051/12378.pdf |
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| Cabanes, Cecile; De Boyer Montegut, Clement; Coatanoan, Christine; Ferry, N.; Pertuisot, Cecile; Von Schuckmann, Karina; Petit De La Villeon, Loic; Carval, Thierry; Pouliquen, Sylvie; Le Traon, Pierre-yves. |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00027/13849/10996.pdf |
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| Azevedo Correia, Joao Marcos; De Boyer Montegut, Clement; Cabanes, Cecile; Klein, Patrice. |
| A method that combines vertical profiles from the ARGO floats program and satellite Sea Surface Height (SSH) data is used to reconstruct the vertical structure of the Agulhas rings. All eddies shed by the Agulhas retroflection in the period between January 2005 and December 2008 were successfully reconstructed. The velocity structures obtained are tilted and phase shifted in relation to the temperature anomalies, resulting in an annual mean eddy meridional heat flux across the ring paths of 0.062 +/- 0.012 PW (northward). A first order estimate indicates 0.07 PW entering the Atlantic from the Indian Ocean through Agulhas rings. The volume transport by Agulhas rings is believed to play a central role in the overturning circulation, being the main process... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00051/16221/13746.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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| Keerthi, M. G.; Lengaigne, M.; Drushka, K.; Vialard, J.; De Boyer Montegut, Clement; Pous, Stephane; Levy, M.; Muraleedharan, P. M.. |
| In this paper, we use an observational dataset built from Argo in situ profiles to describe the main large-scale patterns of intraseasonal mixed layer depth (MLD) variations in the Indian Ocean. An eddy permitting (0.25A degrees) regional ocean model that generally agrees well with those observed estimates is then used to investigate the mechanisms that drive MLD intraseasonal variations and to assess their potential impact on the related SST response. During summer, intraseasonal MLD variations in the Bay of Bengal and eastern equatorial Indian Ocean primarily respond to active/break convective phases of the summer monsoon. In the southern Arabian Sea, summer MLD variations are largely driven by seemingly-independent intraseasonal fluctuations of the... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00332/44335/45788.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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| Mignot, J.; De Boyer Montegut, Clement; Tomczak, M.. |
| Barrier layers are defined as the layer between the pycnocline and the thermocline when the latter are different as a result of salinity stratification. We present a revisited 2-degree resolution global climatology of monthly mean oceanic Barrier Layer (BL) thickness first proposed by de Boyer Montegut et al. (2007). In addition to using an extended data set, we present a modified computation method that addresses the observed porosity of BLs. We name porosity the fact that barrier layers distribution can, in some areas, be very uneven regarding the space and time scales that are considered. This implies an intermittent alteration of air-sea exchanges by the BL. Therefore, it may have important consequences for the climatic impact of BLs. Differences... |
| Tipo: Text |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6915.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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| Praveen Kumar, B.; Vialard, J.; Lengaigne, M.; Murty, V. S. N.; Foltz, G. R.; Mcphaden, M. J.; Pous, S.; De Boyer Montegut, Clement. |
| Sea-surface temperature interannual anomalies (SSTAs) in the thermocline ridge of the southwestern tropical Indian Ocean (TRIO) have several well-documented climate impacts. In this paper, we explore the physical processes responsible for SSTA evolution in the TRIO region using a combination of observational estimates and model-derived surface layer heat budget analyses. Vertical oceanic processes contribute most to SSTA variance from December to June, while lateral advection dominates from July to November. Atmospheric fluxes generally damp SSTA generation in the TRIO region. As a result of the phase opposition between the seasonal cycle of vertical processes and lateral advection, there is no obvious peak in SSTA amplitude in boreal winter, as previously... |
| Tipo: Text |
Palavras-chave: Thermocline ridge of the Indian Ocean; Surface temperature interannual variability; ENSO; IOD. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00185/29642/28051.pdf |
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| Nidheesh, A. G.; Lengaigne, M.; Vialard, J.; Izumo, T.; Unnikrishnan, A. S.; Meyssignac, B.; Hamlington, B.; De Boyer Montegut, Clement. |
| We examine the consistency of Indo-Pacific decadal sea level variability in 10 gridded, observation-based sea level products for the 1960–2010 period. Decadal sea level variations are robust in the Pacific, with more than 50% of variance explained by decadal modulation of two flavors of El Niño–Southern Oscillation (classical ENSO and Modoki). Amplitude of decadal sea level variability is weaker in the Indian Ocean than in the Pacific. All data sets indicate a transmission of decadal sea level signals from the western Pacific to the northwest Australian coast through the Indonesian throughflow. The southern tropical Indian Ocean sea level variability is associated with decadal modulations of ENSO in reconstructions but not in reanalyses or in situ data... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00395/50593/51290.pdf |
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| De Boyer Montegut, Clement; Durand, Fabien; Bourdalle-badie, Romain; Blanke, Bruno. |
| The barrier layer (BL) - a salinity stratification embedded in the upper warm layer - is a common feature of the tropical oceans. In the northern Indian Ocean, it has the potential to significantly alter the air-sea interactions. In the present paper, we investigate the spatio-temporal structure of BL in the Arabian Sea during summer monsoon. This season is indeed a key component of the Asian climate. Based on a comprehensive dataset of Conductivity-Temperature-Depth (CTD) and Argo in situ hydrographic profiles, we find that a BL exists in the central Arabian Sea during summer. However, it is highly heterogeneous in space, and intermittent, with scales of about similar to 100 km or less and a couple of weeks. The BL patterns appear to be closely associated... |
| Tipo: Text |
Palavras-chave: Barrier layer; Arabian Sea; Summer monsoon; ARGO; ASHSW. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00198/30959/29358.pdf |
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| De Boyer Montegut, Clement; Vialard, Jerome; Shenoi, S. S. C.; Shankar, D.; Durand, Fabien; Ethe, Christian; Madec, Gurvan. |
| A global ocean general circulation model (OGCM) is used to investigate the mixed layer heat budget of the northern Indian Ocean (NIO). The model is validated against observations and shows fairly good agreement with mixed layer depth data in the NIO. The NIO has been separated into three subbasins: the western Arabian Sea (AS), the eastern AS, and the Bay of Bengal (BoB). This study reveals strong differences between the western and eastern AS heat budget, while the latter basin has similarities with the BoB. Interesting new results on seasonal time scales are shown. The penetration of solar heat flux needs to be taken into account for two reasons. First, an average of 28 W m(-2) is lost beneath the mixed layer over the year. Second, the penetration of... |
| Tipo: Text |
Palavras-chave: Sea surface temperature; General circulation model; Southeastern arabian sea; Thermal structure; Summer monsoon; Solar radiation; Pacific ocean; Barrier layer; Bengal; Bay. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00185/29639/27985.pdf |
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| Combot, Clement; Quilfen, Yves; Mouche, Alexis; Gourrion, Jerome; De Boyer Montegut, Clement; Chapron, Bertrand; Tournadre, Jean. |
| In this section, a new focus is given on the ocean response induced by Tropical Cyclones. Tropical Cyclones are among the most devastating and destructive natural hazards. Unfortunately, predicting the intensity and evolution of such individual event is still extremely difficult, owing to various internal and environmental factors, including interactions with the ocean interior. In that context, multiple satellite remote sensing observations are essential, and today, combined with denser ARGO interior measurements, the upper ocean responses to moving tropical cyclones can be more efficiently captured and monitored. |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00655/76663/77809.pdf |
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| Vialard, Jerome; Foltz, G. R.; Mcphaden, M. J.; Duvel, J. P.; De Boyer Montegut, Clement. |
| A moored buoy was recently deployed at 8 degrees S, 67 degrees E in the shallow thermocline region of the Indian Ocean known as "Seychelles-Chagos Thermocline Ridge'' (SCTR), where the Madden Julian Oscillation (MJO) is associated with strong sea surface temperature (SST) variability. We use observations from this mooring to describe the oceanic signature of two MJOs between November 2007 and February 2008. The four-month average upper ocean heat balance was largely between heating by atmospheric forcing (2.0 +/- 0.3 degrees C/month) and a significant cooling by subsurface processes (-2.2 +/- 0.8 degrees C/month), consistent with climatological Ekman pumping in the region. The two MJO events resulted in strong intraseasonal SST variations (1.5 to 2 degrees... |
| Tipo: Text |
Palavras-chave: Layer heat balance; Paific; Perturbations; Prediction; Fluxes. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/00185/29636/27988.pdf |
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| Registros recuperados: 23 | |
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