Main eddy vertical structures observed in the four major Eastern Boundary Upwelling Systems

Abstract

In the four major Eastern Boundary Upwelling Systems (EBUS), mesoscale eddies are known to modulate the biological productivity and transport near‐coastal seawater properties toward the offshore ocean, however little is known about their main characteristics and vertical structure. This study combines 10 years of satellite‐altimetry data and Argo float profiles of temperature and salinity, and our main goals are (i) to describe the main surface characteristics of long‐lived eddies formed in each EBUS and their evolution, and (ii) to depict the main vertical structure of the eddy‐types that coexist in these regions. A clustering analysis of the Argo profiles surfacing within the long‐lived eddies of each EBUS allows us to determine the proportion of surface and subsurface‐intensified eddies in each region, and to describe their vertical structure in terms of temperature, salinity and dynamic height anomalies. In the Peru‐Chile Upwelling System, 55% of the sampled anticyclonic eddies (AEs) have subsurface‐intensified maximum temperature and salinity anomalies below the seasonal pycnocline, whereas 88% of the cyclonic eddies (CEs) are surface‐intensified. In the California Upwelling System, only 30% of the AEs are subsurface‐intensified and all of the CEs show maximum anomalies above the pycnocline. In the Canary Upwelling System, ∼40% of the AEs and ∼60% of the CEs are subsurface‐intensified with maximum anomalies extending down to 800 m depth. Finally, the Benguela Upwelling System tends to generate ∼40–50% of weak surface‐intensified eddies and ∼50–60% of much stronger subsurface‐intensified eddies with a clear geographical distribution. The mechanisms involved in the observed eddy vertical shapes are discussed.

Occurrence and characteristics of mesoscale eddies in the tropical northeastern Atlantic Ocean

“…Excluding the mooring-based pro- files, from which we only extracted eddy events, around ∼ 29 % of all profiles (Argo float and shipboard CTD profiles) were taken coincidentally inside of an eddy. This proportion is in the range of earlier results derived by Chaigneau et al (2011), who estimated that ∼ 23 % of their Argo float profiles in the eastern upwelling regions of the Pacific Ocean are conducted in eddies and Pegliasco et al (2015), who found 38 % of all their Argo float profiles in the eastern upwelling areas conducted in eddies. We could also confirm with the result of Pegliasco et al (2015) that the majority of all Argo float profile in eddies are conducted in long-lived anticyclones/ACMEs.…”

Total- and monomethyl-mercury and major ions in coastal California fog water: Results from two years of sampling on land and at sea

“…This is further discussed below. of upwelling, than in anticyclonic eddies, which are mesoscale downwelling centers (Pegliasco et al, 2015). Many more eddies were present during the June cruises compared to those in August, reflecting the seasonal nature of upwelling.…”

Phytoplankton Size Structure in Association with Mesoscale Eddies off Central-Southern Chile: The Satellite Application of a Phytoplankton Size-Class Model

“…There is also a particular type of anticyclonic eddy, called intrathermocline (ITE) or subsurface mode water eddy, which represents 30-55% of the anticyclonic eddy population in Eastern Boundary Current Systems (EBCS) [13]. These eddies (ITEs) are characterized by a typical radius of~20-60 km and have a vertical extent of~500 m, together with dome-shaped isopleths in the upper layers and a bowl shape in the lower layers, a minimum in oxygen, and high rates of phytoplankton productivity [14][15][16][17].…”