  A model of aluminium has been developed and implemented in an Ocean General
Circulation Model (NEMO-PISCES). In the model, aluminium enters the ocean by
means of dust deposition. The internal oceanic processes are described by
advection, mixing and reversible scavenging. The model has been evaluated
against a number of selected high-quality datasets covering much of the world
ocean, especially those from the West Atlantic Geotraces cruises of 2010 and
2011. Generally, the model results are in fair agreement with the observations.
However, the model does not describe well the vertical distribution of
dissolved Al in the North Atlantic Ocean. The model may require changes in the
physical forcing and the vertical dependence of the sinking velocity of
biogenic silica to account for other discrepancies. To explore the model
behaviour, sensitivity experiments have been performed, in which we changed the
key parameters of the scavenging process as well as the input of aluminium into
the ocean. This resulted in a better understanding of aluminium in the ocean,
and it is now clear which parameter has what effect on the dissolved aluminium
distribution and which processes might be missing in the model, among which
boundary scavenging and biological incorporation of aluminium into diatoms.
