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

Type Article
Date 2014-11
Language English
Author(s) Praveen Kumar B.1, Vialard J.2, Lengaigne M.2, Murty V. S. N.3, Foltz G. R.4, McPhaden M. J.5, Pous S.2, 6, de Boyer Montegut ClementORCID7
Affiliation(s) 1 : Govt India, Minist Earth Sci, Indian Natl Ctr Ocean Informat Serv, Hyderabad, Andhra Pradesh, India.
2 : UPMC, Lab Oceanog Experimentat & Approches Numer, CNRS, IRD,MNHN, Paris, France.
3 : CSIR Natl Inst Oceanog, Reg Ctr, Vishakhapatnam, India.
4 : NOAA, Atlantic Oceanog & Meteorol Lab, Miami, FL 33149 USA.
5 : NOAA, Pacific Marine Environm Lab, Seattle, WA 98115 USA.
6 : Univ Cape Town, Dept Oceanog, IRD, LMI ICEMASA, ZA-7925 Cape Town, South Africa.
7 : IFREMER, Ctr Brest, Lab Oceanog Spatiale, F-29280 Plouzane, France.
Source Climate Dynamics (0930-7575) (Springer), 2014-11 , Vol. 43 , N. 9-10 , P. 2377-2397
DOI 10.1007/s00382-014-2059-y
WOS© Times Cited 12
Keyword(s) Thermocline ridge of the Indian Ocean, Surface temperature interannual variability, ENSO, IOD
Abstract 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 Niño induce comparable warming over the TRIO region, though IOD signals peak earlier (November–December) than those associated with El Niño (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 Niño 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.
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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 (2014). Processes of interannual mixed layer temperature variability in the thermocline ridge of the Indian Ocean. Climate Dynamics, 43(9-10), 2377-2397. Publisher's official version : , Open Access version :