The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

1510 / 2024-09-27 20:48:41

Reversal of Multidecadal Sea Level Trends in the Southwest Indian Ocean Thermocline Ridge

Sea level,Multidecadal Variability,Tropical Indian Ocean

In the tropical Southwest Indian Ocean, the multidecadal sea level decline observed in previous studies from the 1960s to the early 2000s has shifted abruptly to a rapid increase of 4.05 ± 0.56 cm/decade over the past two decades. Sea-level budget analysis indicates that manometric sea level accounts for 41% of this rise. Additionally, 30% of the increase is attributed to steric sea level (SSL) changes in the upper 2000 m, with the SSL rise in the upper 300 m being of secondary importance. In contrast, thermal expansion below the thermocline (300–2000 m) constitutes a significant contributor to SSL changes. Furthermore, the observed reversal in multidecadal sea level trends is likely linked to the SAM-related shift in sea surface winds at the beginning of this century. This study underscores the importance of ocean mass and deeper ocean dynamics in a warming climate, in contrast to previous research that primarily focused on thermal variations above the thermocline.