Transport variability in the Lanzarote passage (eastern boundary current of the North Atlantic subtropical Gyre)

Atlantic Meridional Overturning Circulation at 14.5° N in 1989 and 2013 and 24.5° N in 1992 and 2015: volume, heat, and freshwater transports

“…Since the intermediate water at 24.5 • N is composed of both AAIW and MW, the property change over time could be considered an imprint of changing relative contributions of AAIW and MW along the section. On the basin scale, a strengthening of the gyre-scale circulation would bring more AAIW on the western side from lower latitudes, while locally, for instance along the eastern margin, higher salinity in the 2015 realization than in the 1992 realization may reflect a seasonal intrusion of the less saline water near the African coast (Roemmich and Wunsch, 1985;Hernández-Guerra et al, 2005). MW has been reported to occupy a greater portion of the eastern boundary during late winter and early spring, while AAIW contributes more in late fall and early winter (Hernández-Guerra et al, 2003;Fraile-Nuez et al, 2010).…”

“…On the basin scale, a strengthening of the gyre-scale circulation would bring more AAIW on the western side from lower latitudes, while locally, for instance along the eastern margin, higher salinity in the 2015 realization than in the 1992 realization may reflect a seasonal intrusion of the less saline water near the African coast (Roemmich and Wunsch, 1985;Hernández-Guerra et al, 2005). MW has been reported to occupy a greater portion of the eastern boundary during late winter and early spring, while AAIW contributes more in late fall and early winter (Hernández-Guerra et al, 2003;Fraile-Nuez et al, 2010). Machín et al (2009Machín et al ( , 2010 explained the seasonally varying contribution of the AAIW and MW with the stretching and shrinking of the intermediate water strata.…”

Three-dimensional circulation in the NW Africa coastal transition zone

“…In the lifetime of CANIGO, permanent moorings, scientific and opportunity cruises, and remote sensing data provided an improved view of the spatio-temporal variability of the NW Africa system (e.g. Van Camp et al, 1991;Nykjaer and van Camp, 1994;Hernández-Guerra and Nykjaer, 1997;Pacheco and Hernández-Guerra, 1999;Hernández-Guerra et al, 2001;Knoll et al, 2002;Tejera et al, 2002;Hernández-Guerra et al, 2003;Pelegrí et al, 2005a;Pelegrí et al, 2005b;García-Muñoz et al, 2005;Machín et al, 2006a). One main outcome of the CANIGO program was to realize that a major fraction of the eastern boundary recirculation of central waters, or Canary Current (CC), occurs in the CTZ, a relatively narrow region where intense transfer takes place between subsurface and surface waters.…”

“…The complexity of estimating the three-dimensional (3D) flow lies on the difficulty to measure the vertical velocity. Horizontal velocities in the CTZ have been determined either from drifters (Barton et al, 2004;Sangrà et al, 2005;Sangrà et al, 2007), altimetry data (Sangrà et al, 2009), moored currentmeters (Hernández-Guerra et al, 2003), ship-borne ADCP (Knoll et al, 2002) or by applying the thermal wind relation to density profiles (Hernández-Guerra et al, 2001;Barton et al, 2004;Hernández-Guerra et al, 2005;Sangrà et al, 4 2007). The vertical velocity associated to the internal wave field may reach up to O(10 −2 ) m s −1 , therefore also being a measurable variable (van Aken et al, 2007).…”

Atlantic meridional overturning circulation at 14.5° N and 24.5° N during 1989/1992 and 2013/2015: volume, heat and freshwater fluxes

“…Locally, for instance along the eastern margin, higher salinity 10 in the 2015 realization than in the 1992 realization may reflect a seasonal intrusion of the less saline water near the African coast (Roemmich and Wunsch, 1985;Hernández-Guerra et al, 2005). MW has been reported to occupy a greater portion of the eastern boundary during late winter and early spring, while AAIW contributes more in late fall and early winter (Hernández-Guerra et al, 2003;Fraile-Nuez et al, 2010). Machín et al (2009Machín et al ( , 2010 explained the seasonally varying contribution of the AAIW and MW with the stretching and shrinking of the intermediate water strata.…”