On the Near-Surface Salinity Variability of the Caribbean Sea: Present and Future

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DISSERTATION DEFENSE – Giovanni Seijo

Advisor: Donata Giglio, ATOC

LOCATION: SEEC N224

TITLE: On the Near-Surface Salinity Variability of the Caribbean Sea: Present and Future

ABSTRACT:

The Caribbean Sea (CS) is an important pathway of ocean circulation and the island nations within rely on the vast resources it offers. Understanding present day oceanic processes controlling the variability of water properties within the CS at different time scales is critical to understand impacts due to climate change. This presentation is divided into three sections. First, we examine the source behind observed negative salinity anomalies within the Virgin Islands basin (VIB) across a number of oceanographic cruises between 2007 and 2017. We show that the strong seasonal cycle of near-surface salinity is driven by the Amazon and Orinoco river discharges and that inter-annual variability is closely linked to ENSO. Furthermore, we show that horizontal advection is largely responsible for salinity variability and that waters arrive to the VIB via three distinct pathways. We then examine changes to the properties of the CS by the end of the 21st century using high resolution CESM projections. We break down the contributors to the projected salinification of the Caribbean Sea and show that a combination of changes to the ocean circulation and changes to the fluxes between the atmosphere and ocean contribute to the increase salinity. Lastly, we describe the development and validation of CARIB12, a high-resolution ocean-only configuration of CESM-MOM6. The configuration has been developed as a tool to dynamically downscale low-resolution climate projections in support of regional impact studies and decision making. CARIB12 reproduces present day seasonal to interannual variability of temperature, salinity and other relevant ocean properties. Biases in low resolution simulations can be drastically reduced with CARIB12, making it a useful tool for regional climate impacts assessments.

Period	Aug 20 2024
Work for	CU Boulder