SOES6002, Modelling in Environmental and Earth System Science Tim Henstock Toby Tyrrell

One view of modelling: Using maths as a tool to understand parts of the Earth system –Underlying principles may be well or poorly understood –May use numerical or analytical approaches to problem (often both) –May find very complex behaviour in what looks like a simple system

Well-understood principles: Theoretical underpinning (eg physics) all known, and in principle all included in model –Propagation of seismic waves –Effect of mass anomaly on gravitational field –Propagation of EM signals Typically use modelling to explain observations in terms of parameters within the Earth

Poorly-understood principles: Theoretical underpinning (eg physics) in question – may not known what factors important, or have to approximate –Ocean circulation –Ecological systems –Magmatic/hydrothermal processes Typically use modelling to determine which factors are most important, or what types of behaviour are produced by range of parameters

Modelling process: Define important aspects of system Generate equations to describe the interaction of these aspects Use the equations to improve understanding –Analytical solution (maybe symbolic maths) –Numerical modelling –Dimensional/scaling analysis to understand numerical results

Hands-on course on the art and science of numerical modelling Problem with conventional modelling courses: Progress from –Numerical principles (applied mathematics) to –Coding & debugging to –Application (using the model) By the time it comes to the last point, the semester is over!

Here: Focus on intelligent use of models –Models as experimental tools –Practical aspects take centre stage –Lectures (theory) support computer labs Elements of philosophy of modelling –Relationship between simple and complex models –Relationship between models and data Multidisciplinary –Climate; biogeochemical cyles; geophysics –Investigate distinct problems from different disciplines to considerable depth

Assessment: –Entirely through reports based on computer labs (assignments) –Encourage scientific discussion among students and with staff –Write-up of assessments must be by individual alone, although we encourage you to discuss the models you run and the results –Deadlines are strictly enforced (you cannot focus on two assignments simultaneously)

Three modules: –Illustrate uses of modelling in different disciplines –Illustrate different types of modelling approach Geophysics –EM propagation. Forward/inverse modelling Physical oceanography –Thermohaline circulation. Box models, analytical/numerical approaches Ecology –Nutrient systems.

In addition: –Different perspectives on modelling philosophy –You should draw comparisons of the different approaches over the course