Climate Dynamics

, Volume 47, Issue 7–8, pp 2573–2585 | Cite as

A sea surface salinity dipole mode in the tropical Indian Ocean

  • Yuhong Zhang
  • Yan DuEmail author
  • Tangdong Qu


Based on the 10 years sea surface salinity (SSS) data from Argo, we identified a salinity dipole mode in the tropical Indian Ocean, termed S-IOD: a pattern of interannual SSS variability with anomalously low-salinity in the central equatorial and high-salinity in the southeastern tropical Indian Ocean. The S-IOD matures in November–December, lagging the Indian Ocean dipole (IOD) mode derived from sea surface temperature (SST) by 2 months. For the period of observations, the S-IOD persists longer than the IOD, until the following September–October. Oscillations of the two S-IOD poles are governed by different processes. Ocean advection associated with equatorial current variability dominates the SSS anomalies of the northern pole, while surface freshwater flux variability plays a key role in the SSS anomalies of the southern pole, where anomalous precipitation is sustained by preformed sea surface temperature anomalies. The S-IOD concurs with the strong IOD, reflecting an ocean–atmosphere coupling through the SST-precipitation-SSS feedback.


S-IOD SST-precipitation-SSS feedback Tropical Indian Ocean Argo 



We acknowledge the International Argo Program for providing Argo data ( The GPCP precipitation was obtained from the NASA/GSFC ( The OAFlux evaporation was provided by WHOI OAFlux Project of Woods Hole Oceanographic Institution ( The OSCAR currents were provided by NOAA’s Ocean Surface Current Analyses Real Time ( The ORA-S3 wind stress was obtained from ECMWF ( The OISST.V2 was provided by the NOAA Environmental Modeling Center ( This work is supported by the Chinese Academy of Sciences (XDA11010103, XDA11010203), the National Natural Science Foundation of China (41506019, 41525019, 41521005, 41176024), and the CAS/SAFEA International Partnership Program for Creative Research Teams.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.State Key Laboratory of Tropical Oceanography, South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhouChina
  2. 2.International Pacific Research Center, SOEST, University of Hawaii at ManoaHonoluluUSA
  3. 3.Joint Institute for Regional Earth System Science and EngineeringUniversity of CaliforniaLos AngelesUSA

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