Premium
Eddies in the Tropical Atlantic Ocean and Their Seasonal Variability
Author(s) -
Aguedjou H. M. A.,
Dadou I.,
Chaigneau A.,
Morel Y.,
Alory G.
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl083925
Subject(s) - climatology , eddy , altimeter , boundary current , barotropic fluid , upwelling , tropical atlantic , geology , mesoscale meteorology , oceanography , sea surface height , ocean current , latitude , sea surface temperature , amplitude , gulf stream , geography , meteorology , geodesy , physics , turbulence , quantum mechanics
We study mesoscale eddy characteristics in the tropical Atlantic Ocean, using 23 years of daily altimetry sea level anomalies. Eddies are mainly generated in the eastern boundary upwelling systems and in the Brazil Current region. Their westward propagation speed reaches 20 cm/s in equatorial areas, decreasing with latitudes. They present typical amplitudes of 1‐5 cm. The largest and most energetic eddies are observed in the equatorial region, especially in the North Brazil Current (NBC) retroflection. The seasonal cycle of the eddy characteristics shows higher amplitudes along the NBC retroflection and the western part of the North Equatorial Countercurrent. A new criterion, based on altimetry data, determines the probability that barotropic instability of mean surface currents is responsible for eddy generation. We find a strong likelihood that the latter plays a key role along the North Equatorial Countercurrent, whereas other mechanisms must be invoked for the NBC region.