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FORTE is a coarse resolution ocean-atmosphere coupled general circulation model
capable of integrations over timescales ranging from days to thousands of years.
It is also capable of a high degree of flexibility - the model has been designed
with the intention of performing experiments using highly idealised configurations,
so it can accept new continental geometry, land surface orography and ocean bottom
topography easily; the resolution of the ocean (and to a lesser extent, the atmosphere)
is also configurable.
Its principal components are ocean and atmosphere General Circulation Models (GCMs)
originally designed for solo operation. The ocean model is MOMA (Webb,93)
a derivative of the well-known Modular Ocean Model, a z-coordinate primitive equation
model based on the GFDL code. The atmosphere is adapted from IGCM3, a spectral GCM
developed at Reading University (Hoskins,75 Forster,00). They are coupled
together using OASIS (Terray,00), a flexible coupler that allows the models to
pass data between each other whilst running.
The main advantage of this model is that it can be run with relatively modest computing
resources - a recent 100yr integration of the present day climate took ~50 hours
using a desktop PC (AMD 1800XP) and a couple of nodes of a muli-processor Origin 2000,
and initial trials indicate that a higher performance PC (AMD 1900XP) could equal
this on its own.
Currently the model is being run at 4*4 degree resolution using the periodic coupling
method of Sausen and Voss (Sausen,96). Two 100yr control integrations of present day
climate have been run (one with periodic coupling, one without), which reproduced many
of the features of the current state, although it appears that the usual flux adjustments
will be required to iron out some of the less realistic features. The model has also
been tested with a Pangaea like continent as a demonstration of its flexibility, and
is now integrating a 'WaterWorld' scenario in an attempt to reproduce a possible climate
for an entirely water-covered Earth - the first time this has been done with a model of
this complexity.
The ability to run for millennial timescales makes this model suitable for paleo-climate
runs, and there are plans to apply it to geographies similar to those thought to be
present during the cretaceous period in an attempt to provide information about the sort
of climate states that are compatible with that configuration.
Although still beta-level, the model is currently being used by 3 groups
(two here at the Southampton Oceanography Centre and one at Liverpool University) and
the code is being made available as a tool for the modelling community at large. For
more information, email Robin Smith or
Bablu Sinha.
Last Updated :
06 November 2002
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