EGU21-15293
https://doi.org/10.5194/egusphere-egu21-15293
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Sea surface salinity dipole mode in the tropical Indian Ocean and its relationship with Indo-Pacific climate  

Yuhong Zhang1,2,3, Yan Du1,2,3, and Qiwei Sun1,2,3
Yuhong Zhang et al.
  • 1State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China (zhangyuhong@scsio.ac.cn)
  • 2College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
  • 3Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China

An atmospheric channel with the monsoon circulation system and the Walker circulation and an ocean channel with Indonesian through-flow, connect the tropical Indian Ocean and the Pacific, which strongly modulate the Indo-Pacific climate change on different time scales. The atmospheric channel transports 0.35 Sv water vapor from the Indian Ocean to the Pacific on the mean state, while the Indonesia throughflow transports ~15 Sv of freshwater from the western Pacific to the Indian Ocean. These two aspects of freshwater transportation play an important role in maintaining the salinity balance in the tropical Indian Ocean (TIO). On the interannual-decadal time scale, a sea surface salinity dipole mode has been revealed in the tropical Indian Ocean (S-IOD) with salinity anomalies in the central equator and the southeastern TIO is opposite, corresponding to significant wind anomaly along the equator and precipitation and thermocline depth anomalies in the southeastern TIO. The ocean advection forced by wind anomalies along the equator and precipitation and thermocline depth anomalies in the southeastern TIO dominating the SSS variations of the S-IOD, respectively. The modulation of the Indo-Pacific Walker Circulation and its related ocean wave processes transported from the western Pacific through the waveguide in the Indonesian Seas are main factors for the development of S-IOD and its variability, which is forced by the Interdecadal Pacific Oscillation (IPO). Further analyses indicate that the long-term trend of SSS in the global ocean with the salty regions getting saltier and fresh regions getting fresher is modulated by the internal variability associated with the IPO, with the most significant regions in the western tropical Pacific and the southeastern Indian Ocean. Specifically, the IPO leads to a ~40% offset of SSS radiative-forced trend in the western tropical Pacific and ~170% enhancement of the trend in the southeastern Indian Ocean since the mid-20th century.      

How to cite: Zhang, Y., Du, Y., and Sun, Q.: Sea surface salinity dipole mode in the tropical Indian Ocean and its relationship with Indo-Pacific climate  , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15293, https://doi.org/10.5194/egusphere-egu21-15293, 2021.