A prolonged high-salinity event in the Northern Arabian Sea during 2014-2017

A prolonged high-salinity event in the northern Arabian Sea, to the east of the Gulf of Oman, during 2014-2017 was identified based on Argo data sets. The prolonged event was manifested as strengthened spreadings of the surface Arabian Sea high-salinity water and the intermediate Persian Gulf water. We used satellite altimetric data, and geostrophic current data to understand the oceanic processes and the salt budget associated with the high-salinity event. The result indicated that the strengthened high-salinity advection from the Gulf of Oman was one of the main causes of the salinity increase in the northern Arabian Sea. The changes of the seasonally dependent eddies near the mouth of the Gulf of Oman dominated the strengthened high-salinity advection during the high-salinity event as compared with the previous 4-year period: the westward shifted and weakened cyclonic eddy during early winter created a favorable condition for the advection of high-salinity water to the northern Arabian Sea; An anomalous pair of dipolar eddies during early summer strengthened the eastward Ras Al Hadd Jet and its high-salinity advection into the northern Arabian Sea. In addition, the weakened low-salinity advection by coastal currents caused by the weakened monsoon contributed to the maintenance of the high-salinity event. This prolonged high-salinity event reflects the upper ocean responses to the monsoon change and may affect the regional hydrography and biogeochemistry extensively.