Trans-Atlantic Study of Calanus: Modelling the cross-shelf dispersal of Calanus

The objectives of this sub-task of the Trans-Atlantic Study
of Calanus are a) To model the finely resolved flow field
at the shelf edge in each of the following areas - S
Iceland, Faroe, Shetland, W. Norway. b) To explain the
observed seasonal evolution of Calanus distribution and
abundance in each of the above regions using particle
tracking models driven by simulated flow fields.

At present, a nested model system exists only for the
northwest Scottish shelf edge (in the NE Atlantic) as a
product of the ICOS project (MAS2-CT94-0085). In the task,
the same approach was applied to model the Faroese,
Icelandic and Norwegian shelf edge waters. Similarly,
particle tracking schemes to make use of the simulated
flow field have been developed during ICOS and were
applied to the new regions, but will require to be
extended to accommodate application of the proposed
development of circle-map models of generation cycle
characteristics (Subtask 14). The modelling of NSDW
circulation and overflow will be a completely new
development. The basis for the hydrodynamic models will
be the HAMSOM (Hamburg Shelf-Ocean Model) finite difference
coding which has evolved from an original model developed
by Backhaus (1985). The model systems will be used to carry
out a sensitivity analysis of the scope for variability in
climatological forcing at a variety of scales to
influence the success of Calanus in colonising the various
shelf regions, and in the scope for correlations in
population characteristics between shelf regions resulting
from a teleconnection through the deep water circulation.

The modelling work will be shared by three partners.
IFM will develop and apply the hydrodynamic models for the
regions. SINTEF and MLA have collaborated in developing
the particle tracking scheme in IOCS and will continue to
do so in TASC. As in ICOS, the Lagrangian simulations will
be run separately from the hydrodynamic model by
transferring the output data from the HAMSOM model to
SINTEF and MLA for further applications.