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

DRS at CSIR-National Institute of Oceanography

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Title Evidence for the existence of Persian Gulf water and Red Sea water in the Bay of Bengal
 
Creator 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.
Chatterjee, S.
Das, U.
Neema, C.P.
 
Subject Chemistry and Biogeochemistry
Oceanography and Limnology
Saline intrusion
Suspended matter
Chemical composition
Ocean circulation
ISW, Bengal Bay
 
Description 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.
 
Date 2017-05-01T09:29:01Z
2017-09-30T03:12:38Z
2017-05-01T09:29:01Z
2017-09-30T03:12:38Z
2017
 
Type Journal Article
 
Identifier Climate Dynamics, vol.48(9); 2017; 3207-3226
0930-7575
http://drs.nio.org/drs/handle/2264/7694
 
Language en
 
Relation Clim Dynam
SCI
 
Publisher Springer