Climate Dynamics

, Volume 48, Issue 9–10, pp 3207–3226

Evidence for the existence of Persian Gulf Water and Red Sea Water in the Bay of Bengal

  • Vineet Jain
  • D. Shankar
  • P. N. Vinayachandran
  • A. Kankonkar
  • Abhisek Chatterjee
  • P. Amol
  • A. M. Almeida
  • G. S. Michael
  • A. Mukherjee
  • Meenakshi Chatterjee
  • R. Fernandes
  • R. Luis
  • Amol Kamble
  • A. K. Hegde
  • Siddhartha Chatterjee
  • Umasankar Das
  • C. P. Neema
Article

Abstract

The high-salinity water masses that originate in the North Indian Ocean are Arabian Sea High-Salinity Water (ASHSW), Persian Gulf Water (PGW), and Red Sea Water (RSW). Among them, only ASHSW has been shown to exist in the Bay of Bengal. We use CTD data from recent cruises to show that PGW and RSW also exist in the bay. The presence of RSW is marked by a deviation of the salinity vertical profile from a fitted curve at depths ranging from 500 to 1000 m; this deviation, though small (of the order of ~0.005 psu and therefore comparable to the CTD accuracy of 0.003 psu), is an order of magnitude larger than the ~0.0003 psu fluctuations associated with the background turbulence or instrument noise in this depth regime, allowing us to infer the existence of RSW throughout the bay. PGW is marked by the presence of a salinity maximum at 200–450 m; in the southwestern bay, PGW can be distinguished from the salinity maximum due to ASHSW because of the intervening Arabian Sea Salinity Minimum. This salinity minimum and the maximum associated with ASHSW disappear east and north of the south-central bay (85°E, 8°N) owing to mixing between the fresher surface waters that are native to the bay (Bay of Bengal Water or BBW) with the high-salinity ASHSW. Hence, ASHSW is not seen as a distinct water mass in the northern and eastern bay and the maximum salinity over most of the bay is associated with PGW. The surface water over most of the bay is therefore a mixture of ASHSW and the low-salinity BBW. As a corollary, we can also infer that the weak oxygen peak seen within the oxygen-minimum zone in the bay at a depth of 250–400 m is associated with PGW. The hydrographic data also show that these three high-salinity water masses are advected into the bay by the Summer Monsoon Current, which is seen to be a deep current extending to 1000 m. These deep currents extend into the northern bay as well, providing a mechanism for spreading ASHSW, PGW, and RSW throughout the bay.

Keywords

Water masses Indian Ocean Arabian Sea High-Salinity Water Persian Gulf Water Red Sea Water Oxygen minimum zone Summer Monsoon Current CTD 

Supplementary material

382_2016_3259_MOESM1_ESM.pdf (409 kb)
Supplementary material 1 (pdf 408 KB)

Supplementary material 2 (mpg 10061 KB)

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Vineet Jain
    • 1
    • 2
  • D. Shankar
    • 1
    • 2
  • P. N. Vinayachandran
    • 3
  • A. Kankonkar
    • 1
  • Abhisek Chatterjee
    • 1
    • 5
  • P. Amol
    • 1
    • 3
  • A. M. Almeida
    • 1
  • G. S. Michael
    • 1
  • A. Mukherjee
    • 1
    • 5
  • Meenakshi Chatterjee
    • 4
  • R. Fernandes
    • 1
    • 6
  • R. Luis
    • 1
  • Amol Kamble
    • 1
  • A. K. Hegde
    • 1
  • Siddhartha Chatterjee
    • 1
    • 4
  • Umasankar Das
    • 3
    • 7
  • C. P. Neema
    • 3
  1. 1.CSIR-National Institute of Oceanography (CSIR-NIO)GoaIndia
  2. 2.Academy of Scientific and Innovative Research (AcSIR)CSIR-National Institute of Oceanography (CSIR-NIO)GoaIndia
  3. 3.Indian Institute of ScienceBengaluruIndia
  4. 4.Basanti Devi CollegeKolkataIndia
  5. 5.ESSO-Indian National Centre for Ocean Information ServicesHyderabadIndia
  6. 6.Hydrographic Training CentreGeneral Commission for SurveyJeddahSaudi Arabia
  7. 7.India Meteorological DepartmentPuneIndia

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