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$@H/I=Thoppil Prasad Gouri ($@5$8u%b%G%j%s%09V:B(J D1)
$@Bj!!L\!'(JFormation and spreading of Persian Gulf Water mass in the Arabian Sea

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Formation and spreading of Persian Gulf Water mass in the Arabian Sea (Thoppil Prasad Gouri) $@H/I=MW;]!'(J

 The aim of the present study is to establish pathways for water 
 masses in the thermocline and contribute to our understanding 
 of the upper circulation and mixing in the Arabian Sea. The  
 subsurface salinity maxima are used to determine the spreading  
 and mixing of Persian Gulf Water mass (PGW) in the thermocline  
 of the Arabian Sea based on bi-monthly climatology of temperature  
 and salinity. The PGW forms in the Persian Gulf region during  
 winter monsoon on account of excess evaporation over precipitation  
 and turbulent heat loss exceeding the radiative heat gain. This  
 leaves the Persian Gulf region form salinity maxima between  
 200-300 m in the Arabian Sea. PGW is shown to advect along this  
 path on the isopycnal surface $@&R(Jt = 26.5 (depth range 200-300 m).  
 Above and below this surface spreading of PGW is accompanied by  
 small degree of vertical mixing. South of 10$@!k(JN, the spreading  
 of PGW is accompanied by significant isopycnal mixing associated 
 with advection of low salinity water brought by the Equatorial  
 Current system throughout the year.  
  
 The seasonally varying spreading of PGW is in comparable with 
 upper circulation. During winter, the PGW deepens in the  
 southeastern Arabian Sea and propagates westward across the  
 Arabian Sea. This deepening of PGW coincides with the Lakshadweep  
 High seen in the southeastern Arabian Sea. During the southwest  
 monsoon the northwestern part of the core shoals under the influence  
 of the Findlater Jet, while the southeastern part deepens. During  
 summer, the southward spreading of PGW intensifies in the central  
 Arabian Sea, where as in winter the southwestward propagation of  
 PGW along the Somalia coast increases.   

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$@O"Mm@h(J

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mail-to:mizuta@ees.hokudai.ac.jp / Tel: 011-706-2357