Impacts of the upper-ocean salinity variations on the decadal sea level change in the Southeast Indian Ocean during the
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Impacts of the upper-ocean salinity variations on the decadal sea level change in the southeast Indian Ocean during the Argo era Jiamei Huang1, Wei Zhuang1, 2*, Xiao-Hai Yan3, 4, Zelun Wu1, 4 1 State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University,
Xiamen 361102, China 2 Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China 3 Joint Center for Ocean Remote Sensing, University of Delaware-Xiamen University, Newark, DE 19716, USA 4 College of Earth, Ocean, and Environment, University of Delaware, Newark, DE 19716, USA
Received 1 January 2020; accepted 17 February 2020 © Chinese Society for Oceanography and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract
In the past nearly two decades, the Argo Program has created an unprecedented global observing array with continuous in situ salinity observations, providing opportunities to extend our knowledge on the variability and effects of ocean salinity. In this study, we utilize the Argo data during 2004–2017, together with the satellite observations and a newly released version of ECCO ocean reanalysis, to explore the decadal salinity variability in the southeast Indian Ocean (SEIO) and its impacts on the regional sea level changes. Both the observations and ECCO reanalysis show that during the Argo era, sea level in the SEIO and the tropical western Pacific experience a rapid rise in 2005–2013 and a subsequent decline in 2013–2017. Such a decadal phase reversal in sea level could be explained, to a large extent, by the steric sea level variability in the upper 300 m. Argo data further show that, in the SEIO, both the temperature and salinity changes have significant positive contributions to the decadal sea level variations. This is different from much of the Indo-Pacific region, where the halosteric component often has minor or negative contributions to the regional sea level pattern on decadal timescale. The salinity budget analyses based on the ECCO reanalysis indicate that the decadal salinity change in the upper 300 m of SEIO is mainly caused by the horizontal ocean advection. More detailed decomposition reveals that in the SEIO, there exists a strong meridional salinity front between the tropical low-salinity and subtropical high salinity waters. The meridional component of decadal circulation changes will induce strong cross-front salinity exchange and thus the significant regional salinity variations. Key words: decadal sea level change, southeast Indian Ocean, halosteric effect, salinity budget Citation: Huang Jiamei, Zhuang Wei, Yan Xiao-Hai, Wu Zelun. 2020. Impacts of the upper-ocean salinity variations on the decadal sea level change in the southeast Indian Ocean during the Argo era. Acta Oceanologica Sinica, doi: 10.1007/s13131-020-1574-4
1 Introduction As an important consequence of climate variability and change, sea level change has direct impacts on the ecosystem and human life in coastal and island regions. The total sea level variation is
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