HYDRODYNAMIC PROCESSES AND MULTI-SITE FORMATION OF LEVANTINE INTERMEDIATE WATER IN A HIGH-RESOLUTION MODEL OF THE LEVANTINE SEA

Date

2026-2-25

Author

Serimozu, Cem

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The Levantine Sea is a climatically sensitive and dynamically complex region of the Eastern Mediterranean, shaped by intense evaporation, steep topography, and complex circulation. It plays a key role in basin-scale thermohaline circulation by forming Levantine Intermediate Water (LIW). This warm, saline intermediate water mass ventilates the basin and contributes to the Mediterranean overturning. Despite extensive research, uncertainties remain regarding the spatial distribution, variability, and dominant physical controls on LIW formation, mainly due to limited long-term, high-resolution observations. This thesis investigates LIW formation and variability using a newly developed regional configuration of the NEMO ocean model, integrated over the Levantine Sea for the period 1992–2022. The model incorporates realistic atmospheric forcing, river discharge, and open-boundary conditions, providing a high-resolution baseline (2.2 km, 71 vertical levels) for examining intermediate-water processes across seasonal to multi-decadal timescales. Results show that LIW formation in the Levantine Sea operates as a distributed, multi-site process rather than being confined to a single formation hotspot. While the Rhodes Gyre remains the dominant and most persistent formation region, substantial intermittent contributions are identified in the Gulf of Antalya, and episodic formation occurs in the Cilician Basin during periods of strong winter forcing. These findings highlight the importance of regional differences and mesoscale dynamics in modulating LIW. Analyses of surface heat and freshwater fluxes, mixed-layer properties, stratification, and density-space water-mass transformation demonstrate that LIW variability is primarily controlled by thermodynamic forcing. Wintertime buoyancy loss and deep-mixed layers emerge as the dominant mechanisms driving surface densification and subsequent subduction to intermediate depths. In contrast, wind-stress curl and Ekman pumping exhibit weak, statistically marginal associations with LIW events, indicating that wind-driven mechanical forcing plays a secondary role, acting mainly through indirect modulation of the circulation.

Subject Keywords

Eastern Mediterranean Sea, Levantine Intermediate Water, NEMO, Physical Oceanography

URI

https://hdl.handle.net/11511/119001

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Graduate School of Marine Sciences, Thesis