The dominant nutrient supply to the euphotic zone is through winds inducing large-scale upwelling of nutrients from deep waters.
Chlorophyll distribution [g/m3] over the Atlantic Ocean is shown on this map
determined from satellite observations together with the
Ekman velocity (contours in m/year). High concentrations (coloured yellow to red on the map) occur
at high latitudes and near the eastern boundary.
In these regions, the wind forcing leads to upwelling, as shown by the
positive values of Ekman velocity (solid lines). Red line shows AMT10 track.
See also Photos
ynthesis and Nutrient supply
The Ekman velocity is calculated using
NCEP
monthly mean winds, sea-surface and air temperatures covering the periods of transects AMT 1-11 (April/May and September/October 1995-2000).
Two examples of Spring (AMT2 left pannel) and Autumn (AMT3 right pannel)
Ekman velocities are shown below.
The Ekman velocity and the corresponding upwelling and nutrient supply
depends mainly on the curl of the wind stress, containig both seasonal and
interannual variability.
See our
gallery MT
(~700Kb) containing images of seasonal mean Ekman velocity for the period of AMT1 - AMT11.