Evolution of Sea Surface Salinity Anomalies in the Southwestern Tropical Indian Ocean During 2010–2011 Influenced by a Negative IOD Event. Issue 5 (29th May 2019)

• Record Type: Journal Article
• Authors: Sun, Qiwei; Du, Yan; Zhang, Yuhong; Feng, Ming; Chowdary, Jasti S.; Chi, Jianwei; Qiu, Shuang; Yu, Weidong
• Is Part Of: Journal of geophysical research. Volume 124:Issue 5(2019)
• Page Start: 3428
• Page End: 3445
• Publication Date: 2019-05-29
• Subjects: sea surface salinity -- Indian Ocean dipole -- southwestern tropical Indian Ocean -- horizontal advection -- Rossby waves; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2018JC014580
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Using Argo observations and Estimating the Circulation and Climate of the Ocean data sets, this study investigates the sea surface salinity (SSS) variability and its relationship with ocean dynamics in the southwestern tropical Indian Ocean (SWTIO) associated with the 2010 negative Indian Ocean dipole (IOD) event. The results show that the ocean circulation in the tropical southern Indian Ocean (IO) significantly contributes to the SSS anomalies during the evolution of the negative IOD event. The anomalous eastward current advected the high‐salinity water into the eastern equatorial IO during July–October 2010. Then the positive SSS anomalies expanded southward to 6–8°S due to the southeastward mean seasonal currents in the eastern equatorial IO during November–December 2010. A salinity budget analysis has been used to identify key processes in contributing to the SSS variations in the SWTIO. The decreased precipitation in the western and central equatorial IO leads to high SSS anomalies from January to April 2011. Then the anomalous southwestward currents transport the higher SSS water from the eastern equatorial IO to the SWTIO until May–June 2011. At the same time, the upwelling Rossby waves shoal the thermocline and mixed layer depth, bringing high‐salinity subsurface water to the surface layer and cooling the sea surface temperature, which further depresses local precipitation to provide a positive feedback for the SSS increase. Key Points: The horizontal advection dominates the SSS variation during the developing and mature phases of the IOD events Local rainfall and the SEC advection contribute to the positive SSS anomalies in the southwestern tropical Indian Ocean Upwelling Rossby waves shoal thermocline and enhance the positive SSS anomalies