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Argo profiles variability of barrier layer in the tropical Indian Ocean and its relationship with the Indian Ocean Dipole
Author(s) -
Qiu Yun,
Cai Wenju,
Li Li,
Guo Xiaogang
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl051441
Subject(s) - argo , indian ocean dipole , thermocline , upwelling , mixed layer , climatology , salinity , stratification (seeds) , oceanography , geology , barrier layer , kelvin wave , halocline , shoal , atmospheric sciences , indian ocean , environmental science , layer (electronics) , chemistry , seed dormancy , botany , germination , organic chemistry , dormancy , biology
Interannual variability of the barrier layer (BL) in the southeastern tropical Indian Ocean (SETIO) is examined using temperature and salinity profiles derived from Argo floats since 2004. We show that a quasi‐permanent BL exists off Sumatra with a semi‐annual cycle and a maximum in November. Further, interannual variability of the BL is closely related to the Indian Ocean Dipole (IOD) with the IOD leading the BL by one month. During the 2006 positive IOD (pIOD) season, equatorial easterly‐induced upwelling Kelvin waves raise the isothermal layer (IL) off Sumatra; a salinity‐stratified mixed layer (ML) shoals due to a reduced eastward salty water transport by a weaker Wyrtki Jet, despite an offset by a reduced freshwater flux. Consequently, thinning of the BL is dominated by thinning of the IL. During the 2010 negative IOD (nIOD), similar processes operate but in an opposite direction. As thinning of the BL during a pIOD enhances the thermocline‐ML coupling, our results reveal that an IOD‐induced co‐varying BL in turn enhances the IOD positive feedbacks.