Remote Impacts on Caribbean Coastal Sea Level Variability

The Caribbean Sea is characterised by high variability in sea level, mainly caused by eddies and meanders in the mean flow. The Caribbean eddies mainly originate from instabilities in the local currents and can have amplitudes of up to 30 cm. Another source of eddy activity comes from the Atlantic Ocean. Eddies originating there, such as the North Brazil Current rings, are able to penetrate as filaments through the Caribbean island chain. Both types contribute to local sea level variability in the Caribbean. Facing sea level rise it is essential to understand this eddy-induced sea level variability and especially the impact of eddies on coastal waters.

In this study, the Caribbean eddy field was reconstructed from 22 years of altimetry data with automatic eddy-tracking software. This provides information on the main pathways of the eddies and their amplitude, radius and velocity. In areas where eddies tend to get close to the coast, coastal sea level variability was further investigated with high resolution, along-track altimetry data from the Jason missions. Based on the probability distribution and spectral properties of the sea level anomalies, we can make a separation between locally and remotely generated processes. In the spectra of coastal sea level in the southern Caribbean Sea for example, a clear signal is found around a period of 60 days. This period can be associated with the forcing of the North Brazil Current rings. Lower frequencies associated with locally generated eddies seem to be dampened upon the continental shelf. This confirms that there is a remote impact of the Atlantic Ocean on coastal sea level variability in the Caribbean Sea.