Processes of interannual mixed layer temperature variability in the thermocline ridge of the Indian Ocean

Processes of interannual mixed layer temperature variability in the thermocline ridge of the Indian Ocean Kumar B. P. auteur aut IRD Vialard Jérôme auteur aut IRD Lengaigne Matthieu auteur aut IRD Murty V. S. N. auteur aut IRD Foltz G. R. auteur aut IRD McPhaden M. J. auteur aut IRD Pous S. auteur aut IRD Montegut C. D. auteur aut IRD text journalArticle eng text/pdf born digital access 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 noted for heat content anomalies. Positive Indian Ocean Dipole (IOD) events and the remote influence of El Nino induce comparable warming over the TRIO region, though IOD signals peak earlier (November-December) than those associated with El Nino (around March-May). Mechanisms controlling the SSTA growth in the TRIO region induced by these two climate modes differ strongly. While SSTA growth for the IOD mostly results from southward advection of warmer water, increased surface shortwave flux dominates the El Nino SSTA growth. In both cases, vertical oceanic processes do not contribute strongly to the initial SSTA growth, but rather maintain the SSTA by opposing the effect of atmospheric negative feedbacks during the decaying phase. specialized Thermocline ridge of the Indian Ocean Surface temperature interannual variability ENSO IOD OCEAN INDIEN 032 021 020 Climate Dynamics 43 9-10 2377-2397 2014 0930-7575 https://www.documentation.ird.fr/hor/fdi:010062702 10.1007/s00382-014-2059-y 0930-7575 [F B010062702] https://www.documentation.ird.fr/hor/fdi:010062702 https://www.documentation.ird.fr/intranet/publi/2014/12/010062702.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2015-01-12 2017-08-23 fdi:010062702 fre