Introduction to the shelf seas - Introduction to the Physical and Biological Oceanography of Shelf Seas - page 22

the real ocean operates. If the model fails, then we conclude that one or more aspects
of the conceptual model need revision. Generally there is a presumption that we
favour the simplest model (hypothesis); i.e. we follow the approach of Occam's razor,
where we only trade model simplicity for a demonstrable increase in explanatory
power. 1 Thus, only when the simplest model has been convincingly shown to fail do
we proceed to introduce additional features to the model. Following this approach,
models are built up in a logical step-by-step sequence, and by working with the
simplest hypothesis, we keep to a minimum the number of adjustable parameters
which are not well-constrained by theory or observations. Complex, coupled models
of ocean physics, biogeochemistry and ecology can generate outputs that are very
seductive. However, in our view, leaping straight into a complex model without
either sufficient data to set the multitude of driving parameters, or sufficient obser-
vations with which to test the model outputs, is unlikely to lead to any reliable new
insight into how the real world works.
Models of course have other uses. In principle, if well validated, they can be
used to make predictions of, for instance, the response of the ocean to sea level
rise or climate change. They can also be used to answer 'what if' questions such as
those arising from, say, proposals to build a major tidal barrage and the need to
assess near- and far-field changes to a region's tidal characteristics. In the physics
domain such prognostic use of models can be undertaken with some confidence,
but the ability of models to make useful predictions of biological changes in the
shelf seas has not yet been established and remains as a major challenge for our
science.
Throughout this topic we use model-generated examples of the physics and coupled
physics-biogeochemistry of the shelf seas. In all cases we have chosen models that
satisfy our condition of simplicity, and that provide clear insight into the process(es)
under consideration. We have also included a series of model systems on the topic
website ( www.cambridge.org/shelfseas ) that we have developed over the past 20 years
or so in the context of our teaching and research; again, simplicity and insight are
the characteristics we aim for with these models and the exercises based on them.

1.7 The future challenge and rewards of interdisciplinary studies

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We have already indicated that the shelf seas present a major challenge to science
requiring a high degree of interdisciplinary collaboration between physical, chemical
and biological disciplines in order to elucidate the diverse processes of the shelf seas
and their interaction. Given recent improvements in technology, which have greatly
enhanced our capacity to undertake detailed process studies, and the strong founda-
tion in physical understanding which has recently been established, we now see

1 Father William d'Ockam was an English theologian in the fourteenth century. See http://en.wikipedia.
org/wiki/Occam's_razor for a detailed account.