Multi-scale variability of the tropical Indian Ocean circulation system revealed by recent observations
- 8 Downloads
The tropical Indian Ocean circulation system includes the equatorial and near-equatorial circulations, the marginal sea circulation, and eddies. The dynamic processes of these circulation systems show significant multi-scale variability associated with the Indian Monsoon and the Indian Ocean dipole. This paper summarizes the research progress over recent years on the tropical Indian Ocean circulation system based on the large-scale hydrological observations and numerical simulations by the South China Sea Institute of Oceanology (SCSIO), Chinese Academy of Sciences. Results show that: (1) the wind-driven Kelvin and Rossby waves and eastern boundary-reflected Rossby waves regulate the formation and evolution of the Equatorial Undercurrent and the Equatorial Intermediate Current; (2) the equatorial wind-driven dynamics are the main factor controlling the inter-annual variability of the thermocline in the eastern Indian Ocean upwelling; (3) the equatorial waves transport large amounts of energy into the Bay of Bengal in forms of coastal Kelvin and reflected free Rossby waves. Several unresolved issues within the tropical Indian Ocean are discussed: (i) the potential effects of the momentum balance and the basin resonance on the variability of the equatorial circulation system, and (ii) the potential contribution of wind-driven dynamics to the life cycle of the eastern Indian Ocean upwelling. This paper also briefly introduces the international Indian Ocean investigation project of the SCSIO, which will advance the study of the multi-scale variability of the tropical Indian Ocean circulation system, and provide a theoretical and data basis to support marine environmental security for the countries around the Maritime Silk Road.
KeywordsEquatorial undercurrent Equatorial intermediate current Eastern Indian Ocean upwelling Bay of Bengal circulation Multi-scale variability Equatorial wave dynamics Observation and simulation
Unable to display preview. Download preview PDF.
This work was supported by the National Key Research and Development Program of China (Grant No. 2017YFC 1405100), the National Natural Science Foundation of China (Grant Nos. 41521005, 41476011, 41706027, 41676013), the Natural Science Foundation of Guangdong (Grant No. 2016A030310015), the Open Fund of the Key Laboratory of Ocean Circulation and Waves, Chinese Academy of Sciences (Grant No. KLOCW1604), the Open Fund of the State Key Laboratory of Tropical Oceanography (Grant No. LTOZZ1702), the MEL Visiting Fellowship (Grant No. MELRS1640) and the Guangzhou Science and Technology Foundation (Grant No. 201804010133).
- Anderson D L T, Carrington D J. 1993. Modeling interannual variability in the Indian Ocean using momentum fluxes from the operational weather analyses of the United Kingdom Meteorological Office and European Centre for Medium Range Weather Forecasts. J Geophys Res, 98: 12483–12499CrossRefGoogle Scholar
- Gill A E. 1982. Atmosphere-Ocean Dynamics. Orlando: AcademicGoogle Scholar
- Godfrey J S, Hu R J, Schiller A, Fiedler R. 2007. Explorations of the annual mean heat budget of the tropical Indian Ocean. Part I: Studies with an idealized model. J Clim, 20: 3210–3228Google Scholar
- Hood R R, Bange H W, Beal L, Beckley L E, Burkill P, Cowie G L, D’Adamo N, Ganssen G, Hendon H, Hermes J, Honda M, McPhaden M, Roberts M, Singh S, Urban E, Yu W. 2015. The Second International Indian Ocean Expedition (IIOE-2): A basin-wide research program-Science Plan (2015–2020). Delaware: SCOR Newark. 101Google Scholar
- Kuswardani. 2012. The development of a wave-tide-circulation coupled model and its upwelling simulation application in the Indonesian Sea. Dissertation for Doctoral Degree. Qingdao: Ocean University of ChinaGoogle Scholar
- McCreary J P. 1980. Modeling wind-driven ocean circulation. Hawaii Institute of Geophysics Tech. HIG-80-3, 64Google Scholar
- Saji N H, Goswami B N, Vinayachandran P N, Yamagata T. 1999. A dipole mode in the tropical Indian Ocean. Nature, 401: 360–363Google Scholar
- Shankar D, McCreary J P, Han W, Shetye S R. 1996. Dynamics of the East India Coastal Current: 1. Analytic solutions forced by interior Ekman pumping and local alongshore winds. J Geophys Res, 101: 13975–13991Google Scholar
- Swallow J. 1967. The equatorial undercurrent in the western Indian Ocean in 1964. Stud Trop Oceanogr, 5: 15–36Google Scholar
- Wang D X, Wu G X, Xu J J. 1999. Decadal ocean variability and its dynamical interpretation in tropical Indian Ocean (in Chinese). Chin Sci Bull, 44: 1226–1232Google Scholar
- Wei F Y. 2002. Climate Statistical Diagnosis and Prediction Technology. Beijing: Meteorological Press. 343Google Scholar