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Slow westward movement of salinity anomalies across the tropical South Indian Ocean

Citation

Vargas-Hernandez, JM and Wijffels, SE and Meyers, G and Holbrook, NJ, Slow westward movement of salinity anomalies across the tropical South Indian Ocean, Journal of Geophysical Research: Oceans, 120, (8) pp. 5436-5456. ISSN 2169-9275 (2015) [Refereed Article]


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Copyright Statement

Copyright 2015 American Geophysical Union. Vargas-Hernandez, J. Mauro, Wijffels, Susan, Meyers, Gary, Holbrook, Neil J., (2015), Slow westward movement of salinity anomalies across the tropical South Indian Ocean, Journal of Geophysical Research: Oceans, 120(8), 5436--5456, 10.1002/2015JC010933. To view the published open abstract, go to http://dx.doi.org/10.1002/2015JC010933

DOI: doi:10.1002/2015JC010933

Abstract

Decadal salinity variability is an important characteristic of the ocean. It characterizes differences in evaporative and precipitation fluxes at the surface, and in the subsurface it contributes to steric sea level change and freshwater/salt transports. In this paper, we identify and describe westward moving and decadally varying salinity anomalies within the thermocline of the tropical South Indian Ocean (SIO) based on ocean state estimates from the Simple Ocean Data Assimilation version 2.2.4 (SODA). This signature in the salinity anomalies is expressed at the depth of 20C isotherm (D20). A two-dimensional radon transform quantifies the westward speeds as being between 0.4 and 1.7 cm s−1. These speeds are slower than those of first baroclinic-mode Rossby waves or mean advection speeds of the background flow in the same regions. The decadal salinity anomaly originates in the subtropical eastern SIO (∼ 39% of the variance explained) and merges with remote anomalies from the western tropical Pacific Ocean (WTPO) via the Indonesian Seas (∼ 11% of the variance explained). The eastern SIO displays both decadal (∼ 1015 years) and interdecadal (∼ 1530 years) variability influenced by the WTPO, whereas the decadal variability in the western SIO seems to be more influenced by signals originating in the subtropical eastern SIO. We conclude that these salinity anomalies are consistent with signatures of nonlinear baroclinic disturbances as explained in the recent literature, and possible interaction of higher order baroclinic-mode Rossby waves with the mean flow.

Item Details

Item Type:Refereed Article
Keywords:decadal climate variability, salinity anomalies, South Indian Ocean, SODA
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical Oceanography
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate Variability (excl. Social Impacts)
UTAS Author:Vargas-Hernandez, JM (Mr Jose Vargas Hernandez)
UTAS Author:Meyers, G (Professor Gary Meyers)
UTAS Author:Holbrook, NJ (Professor Neil Holbrook)
ID Code:103051
Year Published:2015
Web of Science® Times Cited:6
Deposited By:IMAS Research and Education Centre
Deposited On:2015-09-16
Last Modified:2017-10-31
Downloads:199 View Download Statistics

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