Integrated transports


Details about the calculation of the transport timeseries can be found in McCarthy et al. (2015).

The data for the transport series are available in NETCDF, Matlab or ASCII format.

moc plot

Figure 1: Ten-day (colours) and three month (black) low-pass filtered timeseries of Florida Straits transport (blue), Ekman transport (green), upper mid-ocean transport (magenta), and overturning transport (red) for the period 2nd April 2004 to mid- October 2015. Florida Straits transport is based on electromagnetic cable measurements; Ekman transport is based on ERA winds. The upper mid-ocean transport, based on the RAPID mooring data, is the vertical integral of the transport per unit depth down to the deepest northward velocity (~1100 m) on each day. Overturning transport is then the sum of the Florida Straits, Ekman, and upper mid-ocean transports and represents the maximum northward transport of upper-layer waters on each day. Positive transports correspond to northward flow.

moc plot

Figure 2:Layer transports for thermocline recirculation (magenta) in the depth range 0 to 800m, Intermdiate Water (red - 800 to 1100m), Upper North Atlantic Deep Water (turquoise - 1100 to 3000m) and Lower North Atlantic Deep Water (purple - 3000 to 5000m). The sum of the Upper and Lower North Atlantic Deep Water Transports is the lower limb of the overturning. The correlation of this sum with the AMOC in Figure 1 is R=-0.9902. Negative transports correspond to southward flow. Statistics for these timeseries are Mean±SD : Gulf Stream 31.4±3.1 Sv; Ekman 3.6±3.0 Sv; Upper mid-ocean -18.0±3.4 Sv; MOC : 16.9±4.4 Sv; UNADW -11.9±2.5 Sv; LNADW -5.9±2.9 Sv.

Overturning streamfunction

12-hourly, 2-day low pass filtered overturning streamfunction from April 1st 2004 to October 11th 2015. The streamfunction is the integral of the meridional transport from the surface to the given depth. The MOC is defined as the maximum of the streamfunctoin. Usually the maximum is found at a depth close to 1100m.

moc plot

Figure 3: Vertical MOC structure from April 2004 to October 2015.

National Oceanography Centre Southampton University of Miami
Rosenstiel School of Marine and Atmospheric Science
Atlantic Oceanographic and Meteorological Laboratory