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| Pianezze, J.; Barthe, C.; Bielli, S.; Tulet, P.; Jullien, Swen; Cambon, Gildas; Bousquet, O.; Claeys, M.; Cordier, E.. |
| Ocean-Waves-Atmosphere (OWA) exchanges are not well represented in current Numerical Weather Prediction (NWP) systems, which can lead to large uncertainties in tropical cyclone track and intensity forecasts. In order to explore and better understand the impact of OWA interactions on tropical cyclone modelling, a fully coupled OWA system based on the atmospheric model Meso-NH, the oceanic model CROCO and the wave model WW3 and called MSWC was designed and applied to the case of tropical cyclone Bejisa (2013-2014). The fully coupled OWA simulation shows good agreement with the literature and available observations. In particular, simulated significant wave height is within 30 cm of measurements made with buoys and altimeters. Short-term (< 2 days)... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00428/53983/55169.pdf |
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| Jullien, Swen; Masson, Sébastien; Oerder, Véra; Samson, Guillaume; Colas, François; Renault, Lionel. |
| Ocean mesoscale eddies are characterized by rotating-like and meandering currents that imprint the low-level atmosphere. Such a current feedback (CFB) has been shown to induce a sink of energy from the ocean to the atmosphere, and consequently to damp the eddy kinetic energy (EKE), with an apparent regional disparity. In a context of increasing model resolution, the importance of this feedback, and its dependence on oceanic and atmospheric models resolution arise. Using a hierarchy of quasi-global coupled models with spatial resolutions varying from ¼° to 1/12°, the present study shows that the CFB induces a negative wind work at scales ranging from 100 to 1000 km, and a subsequent damping of the mesoscale activity by ∼30% on average, independently of the... |
| Tipo: Text |
Palavras-chave: Currents; Feedback; Mesoscale processes; Air-sea interaction; Coupled models; Mesoscale models. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00601/71329/69759.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... |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00333/44449/44121.pdf |
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| Dutheil, C.; Lengaigne, Matthieu; Bador, M.; Vialard, J.; Lefèvre, J.; Jourdain, N. C.; Jullien, Swen; Peltier, A.; Sultan, B.; Menkès, C.. |
| Climate model projections generally indicate fewer but more intense tropical cyclones (TCs) in response to increasing anthropogenic emissions. However these simulations suffer from long-standing biases in their Sea Surface Temperature (SST). While most studies investigating future changes in TC activity using high-resolution atmospheric models correct for the present-day SST bias, they do not consider the reliability of the projected SST changes from global climate models. The present study illustrates that future South Pacific TC activity changes are strongly sensitive to correcting the projected SST changes using an emergent constraint method. This additional correction indeed leads to a strong reduction of the cyclogenesis (−55%) over the South Pacific... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00614/72648/71651.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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| Dutheil, Cyril; Bador, M.; Lengaigne, M.; Lefèvre, J.; Jourdain, N. C.; Vialard, J.; Jullien, Swen; Peltier, A.; Menkes, C.. |
| The South Pacific Convergence Zone (SPCZ) is poorly represented in global coupled simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5), with trademark biases such as the tendency to form a “double Intertropical convergence zone” and an equatorial cold tongue that extends too far westward. Such biases limit our confidence in projections of the future climate change for this region. In this study, we use a downscaling strategy based on a regional atmospheric general circulation model that accurately captures the SPCZ present-day climatology and interannual variability. More specifically, we investigate the sensitivity of the projected rainfall response to either just correcting present-day CMIP5 Sea Surface Temperature (SST) biases or... |
| Tipo: Text |
Palavras-chave: Regional climate models; South Pacific Convergence Zone; Precipitation; Sea Surface Temperature. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00484/59603/62636.pdf |
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| Renault, L.; Masson, S.; Oerder, V.; Jullien, Swen; Colas, François. |
| In the past decades, the use of scatterometer data allowed to demonstrate the global ubiquity of the Ocean Mesoscale Thermal FeedBack (TFB) and Current FeedBack (CFB) effects on surface winds and stress. Understanding these air‐sea interactions is of uttermost importance as the induced atmospheric anomalies partly control the ocean circulation, and, thus, can influence the Earth Climate. Whether the TFB and CFB effects can be disentangled, and whether satellite scatterometers can properly reveal them, remain rather unclear. Here, using satellite observations and ocean‐atmosphere coupled mesoscale simulations over 45° S‐45° N, we show that the CFB effect can be properly characterized and unraveled from that due to the TFB. We demonstrate that the TFB can be... |
| Tipo: Text |
Palavras-chave: Mesoscale-air-sea-interactions; Current feedback; Thermal feedback; Scatterometters; Coupling coefficients; Coupled models. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00485/59653/62685.pdf |
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