Semester of Graduation

Spring

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Deep-ocean observations below 2000 meters remain limited, restricting our ability to model global ocean processes critical to climate prediction. This thesis evaluates the potential of SMART (Science Monitoring and Reliable Telecommunications) subsea cables to address these observational gaps by conducting Observing System Simulation Experiments (OSSEs) and adjoint sensitivity analyses using the MITgcm ocean model and ECCO outputs.

Vertical decorrelation analysis showed that temperature and salinity in key regions decouple from the upper ocean beyond 2000 m. Over 60% of the proposed SMART cable sites exhibited decorrelation depths exceeding Argo’s maximum sampling depth, highlighting their strategic value for deployment.

A comparison of the high-resolution ECCO LLC4320 simulation with the coarser LLC270 estimate demonstrates the importance of grid spacing. Globally, the standard deviation of bottom temperature rises from 0.071°C in LLC270 to 0.101°C in the daily LLC4320 fields (42%), while salinity variability increases from 0.0125 PSU to 0.017 PSU (36%). These larger fluctuations reflect the ability of the 1–2 km mesh to resolve mesoscale and submesoscale structures that are smoothed out on the 25 km grid.

Adjoint sensitivity experiments identified high-latitude regions, including the Arctic and Portugal-Azores corridor, as particularly responsive to bottom temperature perturbations, affecting sea surface height and barotropic velocities. However persistent numerical instabilities in salinity and SSH fields, especially in the Beaufort Gyre, suggest a need for improved parameter tuning.

Overall, this work provides a quantitative framework for optimizing SMART subsea cable placement. By targeting underobserved, high-sensitivity regions, these systems can improve global ocean monitoring, strengthen climate models, constrain deep-ocean processes, and support climate resilience.

Date

4-22-2025

Committee Chair

Cheryl Harrisson

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Available for download on Thursday, April 02, 2026

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