Abstract. Understanding phytoplankton dynamics is critical across a range
of topics, spanning from fishery management to climate change mitigation. It is
particularly interesting in the East Australian Current (EAC) system, as the region's
eddy field strongly conditions nutrient availability and therefore phytoplankton growth.
Numerical models provide unparalleled insight into these biogeochemical dynamics. Yet, to
date, modelling efforts off southeastern Australia have either targeted case studies
(small spatial and temporal scales) or encompassed the whole EAC system but focused on
climate change effects at the mesoscale (with a spatial resolution of 1/10∘).
Here we couple a model of the pelagic nitrogen cycle (bio_Fennel) to a 10-year
high-resolution (2.5–5 km horizontal) three-dimensional ocean model (ROMS) to resolve
both regional and finer-scale biogeochemical processes occurring in the EAC system. We
use several statistical metrics to compare the simulated surface chlorophyll to an ocean
colour dataset (Copernicus-GlobColour) for the 2003–2011 period and show that the model
can reproduce the observed phytoplankton surface patterns with a domain-wide RMSE of
approximately 0.2 mg Chl a m−3 and a correlation coefficient of 0.76.
This coupled configuration will provide a much-needed framework to examine phytoplankton
variability in the EAC system providing insight into important ecosystem dynamics such as
regional nutrient supply mechanisms and biogeochemical cycling occurring in EAC eddies.
A high-resolution biogeochemical model (ROMS 3.4 + bio_Fennel) of the East Australian Current system
