Distribution and spreading of Red Sea Water and salt lens formation in the northwest Indian Ocean

Abstract

A long-term hydrographic data set collected between 1935 and 1981 is used to examine the spreading and mesoscale structure of Red Sea Water (RSW) in the northwest Indian Ocean. Four main branches of RSW are identified by statistical methods. It is shown by water mass and isopycnal analyses, that the spreading of RSW occurs partially as high-salinity, isolated patches (lenses), some of which also have positive temperature anomalies. Typical thermohaline properties of the RSW lenses (“Reddies”) are summarized. All of the identified Reddies are found in the regions where the factor P (which denotes the probability of RSW being present at a hydrographic station) has high horizontal gradients. The most probable mechanism of Reddy generation is the instability of the RSW main tongue.