On the Seasonal variability in the eastern boundary of the North
Atlantic Subtropical Gyre
Abstract
For the first time in 2015, four dedicated hydrographic cruises – one
in each season – took place around the Canary Islands to determinate
the seasonality of the flows at the eastern boundary of the North
Atlantic Subtropical Gyre. The Canary Current (CC) is the eastern
boundary current of the North Atlantic Subtropical Gyre and links the
Azores Current with the North Equatorial Current. The CC shows a
seasonal behavior in its path and strength, flowing on its easternmost
position in winter (3.4±0.3 Sv), through the Canary Islands in spring
(2.1±0.7 Sv) and summer (2.0±0.6 Sv) and on its westernmost position in
fall (3.2±0.4 Sv). At the Lanzarote Passage (LP), the dominant flow is
southward except in fall, where a northward transport is observed at
surface (1.1±0.3 Sv) and intermediate (1.3±0.2 Sv) layers. A historical
composite observational seasonal cycle is built from all the available
estimations on the area and fits the 2015 seasonal cycle. The LP
seasonal cycle and seasonal amplitude match the seasonal cycle of the
Atlantic Meridional Overturning Circulation (AMOC) measured by
the RAPID-MOCHA data array.