DOI: 10.5281/zenodo.13625095
title: Census of Cyclonic Eddies formed south of the Gulf Stream from 2000 to 2023

description: This dataset contains the dates and locations of Gulf Stream cyclonic eddy formation and demises along with their surface area at each of these times. The methodology to document and analyze the presence of Gulf Stream cyclonic eddies emulated the GIS-based process used to generate the 38-year warm-core ring census described by Gangopadhyay et al., (2020) and published by Gangopadhyay & Gawarkiewicz (2020). This study continued the use of the Jenifer Clark Charts of the Gulf Stream (Clark Charts) to identify cyclonic eddies. The Clark Charts are synoptic oceanographic analysis charts that employ SST, altimetry, and field observations to map the path of the Gulf Stream, location and size of warm and cold eddies and adjacent filaments. They have been consistently produced two to three times per week since 1980. Thus, we used approximately 3,700+ Charts for the 24 years of analysis. All of these charts were reanalyzed between -75° and -55°W using QGIS 3.30.3-'s-Hertogenbosch (2023) and geo-referenced on a WGS84 coordinate system (Decker, 1986).

This census accounts for all cyclonic eddies from 2000-2023 in the Sargasso Sea between the Gulf Stream extension and 33°N. This census has a total of 595 eddies consisting of 303 hook-type eddies, 140 pinch-off rings, and 152 Sargasso eddies. The formation and demise of Gulf Stream cyclonic eddies from 1980-2019 within the area of study were previously examined by Silver et al. (2021). Findings of this census suggest three different cyclonic eddy formation types: pinch-off cyclonic rings, hook-type cyclonic eddies, and Sargasso Sea cyclonic eddies. Pinch-off cyclonic rings form from a Gulf Stream meander trough amplifying, then encircling Slope Sea water and eventually detaching from the Gulf Stream as a cyclonic cold-core ring in the Sargasso Sea. Hook-type eddies form from a southward extending filament of the southern flank of the Gulf Stream establishing as a hook-like entity cyclonically encircling a body of Sargasso Sea water at its core. Sargasso Sea cyclonic eddies are isolated from the Gulf Stream and occur in the Sargasso Sea.

The format of the dataset is similar to that of the warm-core ring (WCR) census in Gangopadhyay et al., 2020, except that this census table contains the ‘type of formation’ as discussed above (Also see Jensen, 2024). This dataset is a single file of a table containing each cyclonic eddy’s center location and its surface area at the times of its birth (DOB) and demise (DOD) between January 1, 2000 to December 31, 2023. On formation, each cyclonic eddy (CE) was assigned a unique identification code consisting of “CE”, followed by the four-digit year of formation, two-digit month and day of formation, and a subsequent letter of the alphabet. The alphabetical sequence started by assigning the first letters of the alphabet to the eddies that carried over from the previous year and then the first new cyclonic eddy born received the next letter in the alphabet. For example, if there were six eddies from the previous year, they would be labeled A-F. If the next cyclonic eddy was born on January 7, 2021, it would be identified as “CE20210107G”. This ID code was also used to label the same eddy at its demise.

Each row of the census table contains variables “CEID” for the eddy’s identification code, “FORMTYPE” – the eddy’s formation type, “DOB” – the eddy’s date of formation, “BLON_W”- the eddy center’s longitude (W) at formation, “BLAT_N”- the eddy center’s latitude (N) at formation, “BAREAIN_km2” - the area of the eddy’s inner core size in km^2 at formation, “BAREAOUT_km2” - the area of the eddy’s outer annulus of Gulf Stream water (including the inner core area) in km^2 at formation, “DOD” – the eddy’s date of demise, “DLON_W”- the eddy center’s longitude (W) at demise, “DLAT_N”- the eddy center’s latitude (N) at demise, “DAREAIN_km2” - the area of the eddy’s inner core size in km^2 at demise, and “DAREAOUT_km2” - the area of the eddy’s outer annulus of Gulf Stream water (including the inner core area) in km^2 at demise. An “NA” in either the “BAREAOUT_km2” or “DAREAOUT_km2” column indicates that there was no annulus of Gulf Stream water present around the eddy’s core.