Statistics of Brazil Current rings observed from AVHRR: 1993 to 1998

Abstract

[1] A 6-year time series of sea surface temperature fields derived from NOAA polar-orbiter AVHRR 5-day composites is used to estimate the lifetime, size, and trajectory of 43 warm-core rings shed by the Brazil Current at the Southwestern Atlantic region in a consistent fashion for the first time. Ring lifetimes range from 11 to 95 days, and are not bi-modal as is the case for the Gulf Stream anticyclones. Translational speeds range from 4.2 to 27.2 km/day with a mean value of 13.1 km/day. After formation, rings are mostly elliptical with a mean major radius of 126 ± 50 km and a minor radius of 65 ± 22 km. None of the rings seem to last more than four months in the region. An attempt to explore possible connections between ring shedding variability and the Antarctic Dipole is also addressed.

Eddy-Train Encounters with a Continental Boundary: A South Atlantic Case Study

“…Lebedev and Nof 1997;Witter and Gordon 1999;Wainer et al 2000;Lentini et al 2002). The study of Arruda et al (2004) suggests that temporal variations in BC transport upstream of the zone can affect the detachment of intrusion eddies at the BMCZ.…”

An Improved Automatic Algorithm for Global Eddy Tracking Using Satellite Altimeter Data

“…The search area is an "ellipse" with a zonally oriented major axis. The western boundary of the ellipse is the distance from the eddy core, which is determined from the maximum value between 1.75 times the daily long Rossby wave propagation distance [41] and the mean mesoscale eddy propagation distance on the order of 10 km per day [42,43]. However, since 150 km was set as the minimum search range for weekly data by Chelton et al [2] and we used daily data, the maximum daily travel distance of an eddy should be approximately 21 km.…”

The impact of mesoscale eddies on the air-sea turbulent heat fluxes in the South Atlantic

“…This decay in the chlorophyll concentration at the eddy cores, was also observed on SST and SLA signals as a consequence of the mixing of the eddies with warmer and low chlorophyll concentration waters. By following the chlorophyll maximum in the eddy centers, the authors estimated a propagation velocity of ∼12 km/day, which was in accordance with the results of Lentini et al (2002). Moreover, To summarize, the dynamics of the BMC is dominated by mesoscale eddies.…”

“…The surface temperature at the eddy core was of 19. A robust statistics of warm-core mesoscale eddies shed by the BC into the BMC region was presented by Lentini et al (2002). The authors identified and followed a total of 43 anticyclonic eddies using 6 years of SST data from AVHRR.…”