Abstract
The region between the southern tip of the Indian subcontinent and the equator links the Arabian Sea and the Bay of Bengal. A significant exchange of mass, heat and salt occurs in the region via two major current systems: the monsoon current (dominant annual cycle) and the equatorial current (dominant semi-annual cycle). This paper presents observations from deep-sea mooring programmes and describes the rationale for maintaining a mooring array along 77.4\(^\circ \)E to monitor both current systems. Analysis shows that the semi-annual to annual cycle transition occurs at 2–2.5\(^\circ \)N, with the winter monsoon current peaking at 5\(^\circ \)N, the summer monsoon current at 3–6\(^\circ \)N, and the equatorial current at 0–1\(^\circ \)N.
Research highlights
-
1.
Ocean current observations are shown in the monsoon and equatorial currents regime at 77.4\(^\circ \)E.
-
2.
The transition between monsoon and equatorial current occurs at 2-2.5\(^\circ \)N.
-
3.
Summer (winter) monsoon current is strongest at 3-6\(^\circ \)N (5\(^\circ \)N).
-
4.
Minor expansion of existing mooring programmes to monitor two major current systems in the North Indian Ocean is proposed.
This is a preview of subscription content, log in via an institution to check access.
References
Amol P, Bemal S, Shankar D, Jain V, Thushara V, Vijith V and Vinayachandran P 2020 Modulation of chlorophyll concentration by downwelling Rossby waves during the winter monsoon in the southeastern Arabian Sea; Progr. Oceanogr. 186 102,365, https://doi.org/10.1016/j.pocean.2020.102365.
Amol P, Jain V and Aparna S 2022 Blue-shifted deep ocean currents in the equatorial Indian Ocean; Clim. Dyn. 59 1–11; https://doi.org/10.1007/s00382-021-06125-9.
Chaudhuri A, Shankar D, Aparna S G, Amol P, Fernando V, Kankonkar A, Michael G S, Satelkar N P, Khalap S T, Tari A P, Gaonkar M G, Ghatkar S and Khedekar R R 2020 Observed variability of the West India Coastal Current on the continental slope from 2009–2018; J. Earth Syst. Sci. 129, https://doi.org/10.1007/s12040-019-1322-3.
Francis P A, Jithin A K, Effy J B, Chatterjee A, Chakraborty K, Paul A, Balaji B, Shenoi S S C, Biswamoy P, Mukherjee A, Singh P, Deepsankar B, Reddy S S, Vinayachandran P N, Kumar M S G, Bhaskar T V S U, Ravichandran M, Unnikrishnan A S, Shankar D, Prakash A, Aparna S G, Harikumar R, Kaviyazhahu K, Suprit K, Shesu R V, Kumar N K, Rao N S, Annapurnaiah K, Venkatesan R, Rao A S, Rajagopal E N, Prasad V S, Gupta M D, Nair T M B, Rao E P R and Satyanarayana B V 2020 High-resolution operational ocean forecast and reanalysis system for the Indian Ocean; Bull. Am. Meteorol. Soci 101 E1340–E1356. https://doi.org/10.1175/BAMS-D-19-0083.1.
Jain V, Amol P, Aparna S G, Fernando V, Kankonkar A, Murty V S N, Almeida A M, Sardar A A, Khalap S T, Satelkar N P, Ghatkar S, Tari P A, Gaonkar M G and Khedekar R 2021 Two decades of current observations in the equatorial Indian Ocean; J. Earth Syst. Sci. 130, https://doi.org/10.1007/s12040-021-01568-4.
Jain V, Shankar D, Vinayachandran P N, Kankonkar A, Chatterjee A, Amol P, Almeida A M, Michael G S, Mukherjee A, Chatterjee M, Fernandes R, Luis R, Kamble A, Hegde A K, Chatterjee S, Das U and Neema C P 2017 Evidence for the existence of Persian Gulf Water and Red Sea Water in the Bay of Bengal; Clim. Dyn. 48 3207–3226, https://doi.org/10.1007/s00382-016-3259-4.
McPhaden M J, Meyers G, Ando K, Masumoto Y, Murty V S N, Ravichandran M, Syamsudin F, Vialard J, Yu L and Yu W 2009 RAMA: The research moored array for African–Asian–Australian Monsoon analysis and prediction; Bull. Am. Meteorol. Soc. 90 459–480; https://doi.org/10.1175/2008BAMS2608.1.
Reppin J, Schott F A, Fischer J and Quadfasel D 1999 Equatorial currents and transports in the upper central Indian Ocean: Annual cycle and interannual variability; J. Geophys. Res. 104 15,495–15,514, https://doi.org/10.1029/1999JC900093.
Schopf P S, Anderson D L T and Smith R 1981 Beta-dispersion of low-frequency Rossby waves; Dyn. Atmos. Oceans 5 187–214, https://doi.org/10.1016/0377-0265(81)90011-7.
Schott F A and McCreary J P 2001 The monsoon circulation of the Indian Ocean; Progr. Oceanogr. 51 1–123, https://doi.org/10.1016/S0079-6611(01)00083-0.
Schott F, Reppin J, Fischer J and Quadfasel D 1994 Currents and transports of the Monsoon Current south of Sri Lanka; J. Geophys. Res. 99 25,127–25,141, https://doi.org/10.1029/94JC02216.
Shankar D, Vinayachandran P N and Unnikrishnan A S 2002 The monsoon currents in the north Indian Ocean; Progr. Oceanogr. 52 63–120, https://doi.org/10.1016/S0079-6611(02)00024-1.
Vinayachandran P, Chauhan P, Mohan M and Nayak S 2004 Biological response of the sea around Sri Lanka to summer monsoon; Geophys. Res. Lett. 31, https://doi.org/10.1029/2003GL018533.
Wang Y and McPhaden M J 2017 Seasonal cycle of cross-equatorial flow in the central Indian Ocean; J. Geophys. Res. 122 3817–3827, https://doi.org/10.1002/2016JC012537.
Zeng L, Chen G, Huang K, Chen J, He Y, Zhou F, Yang Y, Liang Z, Peng Q, Shi R, Gamage T P, Chen R, Li J, Zhang Z, Wu Z, Yu L and Wang D 2021 A decade of eastern tropical Indian Ocean Observation Network (TIOON); Bull. Am. Meteorol. Soc. 102 E2034–E2052, https://doi.org/10.1175/BAMS-D-19-0234.1.
Acknowledgements
The authors thank D Shankar for his critical comments. The support from A Chaudhuri, CSIR-NIO mooring group (V Fernando, N P Satelkar, S T Khalap, S Ghatkar, P A Tari and M G Gaonkar), A Kankonkar, ship cell members, officers, crew, and seamen from various cruises is gratefully acknowledged. The mooring operations were carried out on the research vessels ORV Sagar Kanya, RV Sindhu Sadhana, and TDV Sagar Nidhi. VJ acknowledges funding support from ESSO-INCOIS. We acknowledge the following sources for data: The OSCAR-current products were obtained from the NASA EOSDIS Physical Oceanography Distributed Active Archive Center (PO.DAAC) at the Jet Propulsion Laboratory, Pasadena, CA. Python modules were used for analysis and graphics. This is CSIR-NIO contribution no. 6926.
Author information
Authors and Affiliations
Contributions
Vineet Jain and P Amol drafted the manuscript. Vineet Jain and P Amol processed, analysed, and interpreted the data. Vineet Jain, P Amol and S G Aparna conceived and designed the study.
Corresponding author
Additional information
Communicated by C Gnanaseelan
Supplementary materials pertaining to this article are available on the Journal of Earth System Science website (http://www.ias.ac.in/Journals/Journal_of_Earth_System_Science).
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Jain, V., Amol, P. & Aparna, S.G. On monitoring two major current systems of the north Indian Ocean using an array of deep-sea moorings. J Earth Syst Sci 131, 218 (2022). https://doi.org/10.1007/s12040-022-01971-5
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s12040-022-01971-5