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Abstract Submission No. | ABS-2022-04-0008 |
Title of Abstract | Pathways and Transit Times of the Red Sea Overflow Water in the Indian Ocean from Lagrangian Simulations |
Authors | Viviane Menezes* |
Organisation | Woods Hole Oceanographic Institution |
Address | 266 woods hole road woods hole, MASSACHUSETTS, United States Pincode: 02543 Mobile: 17748364199 E-mail: vmenezes@whoi.edu |
Country | United States |
Presentation | Oral |
Abstract | The present study investigates the advective pathways and transit times of virtual particles released in the Red Sea outflow area as a proxy for the poorly understood Red Sea Overflow Water (RSOW) spreading. This work uses the Parcels toolbox, a Lagrangian framework, to simulate tens of thousands of trajectories under different initial conditions. All simulations are based on the eddy-rich GLORYS12 reanalysis that merges almost all in-situ (temperature-salinity) and satellite observations collected over the last two decades into a dynamical framework. This study shows that GLORYS12 reproduces relatively well the climatological seasonal cycle of the RSOW to the Gulf of Aden and essential characteristics of the exchange at the Strait of Bab al-Mandab. Statistical comparisons between synthetic trajectories and RAFOS floats in the Gulf of Aden corroborate the quality of GLORYS12 velocity fields used for the Lagrangian simulations. Experiments were designed to identify the typical pathways, evaluate how the eddy field impacts the probability distributions (and time scales), the effects of the monsoonal circulation variability. In the Arabian Sea, six main advective pathways are uncovered (by order of preference): Southwest, Northwest, Socotra Passage, Central, Eastern, and Southern. Trajectories from Argo floats give observational support for some of these paths. Transit time distributions indicate that it takes about six months for outflow-originated particles to spread over the entire Gulf of Aden and one to three years to be exported along the western boundary, toward Somalia (through the wintertime Socotra Passage and Southwest pathways) and off the Yemeni-Omani coast (Northwest Pathway). In contrast, reaching the Arabian Sea eastern boundary takes much longer. North of 14o N, the most frequent time is around 10-15 years and about 20-25 years at the southeastern Arabian Sea. Hence, the RSOW can often carry oxygen to the western boundary but not to the eastern basin. This may contribute to the eastern shift of the Arabian Sea Oxygen Minimum Zone, a subject that deserves investigation. Statistical analysis of the particles outside the Arabian Sea is currently under analysis. Special attention is being given to how the RSOW spreads in the South Indian Ocean. |