Simulated seasonal and interannual variability of the mixed layer heat budget in the northern Indian Ocean

Type Article
Date 2007-07
Language English
Author(s) de Boyer Montegut ClementORCID1, Vialard Jerome1, Shenoi S. S. C.2, Shankar D.2, Durand Fabien3, Ethe Christian1, Madec Gurvan1
Affiliation(s) 1 : Inst Pierre Simon Laplace, Lab Oceanog & Climat Experimentat & Approches Num, Paris, France.
2 : Natl Inst Oceanog, Phys Oceanog Div, Panaji, Goa, India.
3 : Inst Rech Dev, Lab Etud Geophys & Oceanog Spatiales, Toulouse, France.
Meeting Climate Variability and Predictability Studies Workshop on Indian Ocean Climate, Honolulu, HI, NOV 29-DEC 03, 2004
Source Journal Of Climate (0894-8755) (Amer Meteorological Soc), 2007-07 , Vol. 20 , N. 13 , P. 3249-3268
DOI 10.1175/JCLI4148.1
WOS© Times Cited 77
Keyword(s) sea surface temperature, general circulation model, southeastern arabian sea, thermal structure, summer monsoon, solar radiation, pacific ocean, barrier layer, bengal, bay
Abstract 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 solar heat flux tends to reduce the effect of solar heat flux on the SST seasonal cycle in the AS because the seasons of strongest flux are also seasons with a thin mixed layer. This enhances the control of SST seasonal variability by latent heat flux. The impact of salinity on SST variability is demonstrated. Salinity stratification plays a clear role in maintaining a high winter SST in the BoB and eastern AS while not in the western AS. The presence of freshwater near the surface allows heat storage below the surface layer that can later be recovered by entrainment warming during winter cooling (with a winter contribution of + 2.1 degrees C over left right C in the BoB). On an interannual time scale, the eastern AS and BoB are strongly controlled by the winds through the latent heat flux anomalies. In the western AS, vertical processes, as well as horizontal advection, contribute significantly to SST interannual variability, and the wind is not the only factor controlling the heat flux forcing.
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de Boyer Montegut Clement, Vialard Jerome, Shenoi S. S. C., Shankar D., Durand Fabien, Ethe Christian, Madec Gurvan (2007). Simulated seasonal and interannual variability of the mixed layer heat budget in the northern Indian Ocean. Journal Of Climate, 20(13), 3249-3268. Publisher's official version : , Open Access version :