Perspectives of seasonal hydrography and water masses in Saudi waters of the Arabian Gulf

The hydrographic characteristics and water mass features of the Saudi waters of the Arabian Gulf (Persian Gulf) are less documented compared to neighboring regions. This study analyzed vertical profiles of temperature, salinity, and density collected from five transects with 555 stations in Saudi waters during five seasons. Although the data were collected during 2002–2003, they reveal notable hydrographic variability and features associated with Saudi waters. The sea surface temperature during late autumn and winter shows strong horizontal fluctuations between the northern and southern belts of the Saudi coast, while a high temperature plume is formed in the central coast during early summer. The central and northern coasts of Saudi Arabia have high concentrations of salinity induced by shallow embayments, while the impact of brine is limited to small areas in the vicinity of the outfalls. The presence of three water masses, namely, Indian Ocean Surface Water (IOSW), Arabian Gulf Water (AGW), and Bay Systems-induced Water (BSW), has been evident in this region; however, they co-occur only during spring, early summer, and summer in central and northern transects. The autumn and winter are characterized by the presence of AGW and BSW in all transects, while the IOSW was absent due to the mixing and by the opposing effects of shamal winds, which diminishes the inflow of IOSW. Nonetheless, the early summer and summer, with strong thermal stratification, exhibit the progression of IOSW up to the northern end of the Saudi waters.