Recent sea level changes in the Red Sea: Thermosteric and halosteric contributions, and impacts of natural climate variability

Abstract

This study investigates sea level changes in the Red Sea over the last 29 years (1993–2021) by analyzing long-term trends and interannual variations in the total sea level anomaly (SLA). The study also explores the role of thermosteric and halosteric changes and interannual variability of total SLA using an empirical orthogonal function (EOF) analysis and their relationship with large-scale climate modes. The results show that the trends of total and steric SLA were higher in the northern Red Sea (NRS) than in the southern Red Sea (SRS), influenced by low-salinity water inflow from the Aden Gulf. The average SLA trend in the Red Sea between 1993 and 2021 was about 4.17 ± 0.14 mm/year. However, an abrupt change was observed in SLA and its components, with accelerating trends in the post-2008 period compared to the pre-2008 period. This increase was mainly due to the thermosteric effect, which was positively enhanced throughout the Red Sea. The halosteric component in the NRS contributed negatively to the overall steric effect. The interannual SLA variability accounts for about 45 % of the total variability and can be partially explained by the influence of the El Nino Southern Oscillation.