Rapid Sea Level Rise in the Tropical Southwest Indian Ocean in the Recent Two Decades

• Main Authors: Huang, Lei, Zhuang, Wei, Lu, Wenfang, Zhang, Yang, Edwing, Deanna, Yan, Xiao-Hai
• Format: Article in Journal/Newspaper
• Language: English
• Published: Geophysical Research Letters 2023
• Subjects: tropical Southwest Indian Ocean; sea level variability; mass-induced component; steric height; deep ocean changes; Southern Ocean
• Online Access: https://udspace.udel.edu/handle/19716/34207

This article was originally published in Geophysical Research Letters. The version of record is available at: https://doi.org/10.1029/2023GL106011. © 2023. The Authors. It has been reported that the sea level falls in the tropical Southwest Indian Ocean (SWIO) from the 1960s to the early 2000s. However, a rising trend of 4.05 ± 0.56 cm/decade has occurred during the recent two decades with our analysis showing that manometric sea level contributes 41% to this sea level rise. 30% of this rise is due to steric sea level (SSL) change in the upper 2,000 m with SSL rise in the upper 300 m of secondary importance. Conversely, thermal expansion below the thermocline (300–2,000 m), likely caused by water mass spread from the Southern Ocean, induces major contribution to SSL changes. Compared to existing studies demonstrating the contribution of thermal variations above the thermocline to sea level variability in the tropical SWIO, this study emphasizes the importance of ocean mass and deeper ocean changes in a warming climate. Key Points - Rapid sea level rise occurs in the tropical Southwest Indian Ocean (SWIO) since the early 2000s - The ocean mass addition and the upper 2,000 m ocean warming contribute significantly to the total sea level rise - The upper 2,000 m ocean warming is primarily attributed to thermal expansion below the thermocline associated with the spread of water masses Plain Language Summary Global ocean sea level change is spatially and temporally nonuniform due to oceanic and atmospheric dynamics. The tropical Southwest Indian Ocean (SWIO) experienced a sea level fall from the 1960s to the early 2000s. However, a rapid sea level rise has occurred over the last two decades in the tropical SWIO that is faster than the global average. The ocean mass increase due to extra water input leads to an essential impact on sea level rise in the tropical SWIO. Compared to previous studies demonstrating the effect of thermal expansion in the upper 300 m, this study shows larger contributions from deeper ocean ...