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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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| 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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| 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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| Samson, G.; Masson, S.; Lengaigne, M.; Keerthi, M. G.; Vialard, J.; Pous, Stephane; Madec, G.; Jourdain, N. C.; Jullien, Swen; Menkes, C.; Marchesiello, P.. |
| This paper presents the NOW regional coupled ocean-atmosphere model built from the NEMO ocean and WRF atmospheric numerical models. This model is applied to the tropical Indian Ocean, with the oceanic and atmospheric components sharing a common 1/4 degrees horizontal grid. Long experiments are performed over the 1990-2009 period using the Betts-Miller-Janjic (BMJ) and Kain-Fritsch (KF) cumulus parameterizations. Both simulations produce a realistic distribution of seasonal rainfall and a realistic northward seasonal migration of monsoon rainfall over the Indian subcontinent. At subseasonal time scales, the model reasonably reproduces summer monsoon active and break phases, although with underestimated rainfall and surface wind signals. Its relatively high... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00349/46036/45703.pdf |
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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... |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00360/47134/47083.pdf |
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| Keerthi, M. G.; Levy, M.; Aumont, Olivier; Lengaigne, Matthieu; Antoine, D.. |
| Understanding long‐term variations of ocean ecosystems requires untangling the time scales involved in their natural fluctuations. We applied a temporal decomposition procedure to two decades of satellite ocean color observations to characterize the time variability of surface Chlorophyll‐a (SChl) in the Mediterranean Sea. In order to assess the reliability of the satellite data at capturing intraseasonal, seasonal and interannual variability, we first show that satellite SChl data compare well with field data of phytoplankton fluorescence from the long‐term BOUSSOLE time series, at all three timescales. The decomposition procedure is then applied to satellite SChl and to mixing‐layer depth (MxLD) data from an ocean reanalysis, both at the scale of the... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00624/73654/73098.pdf |
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