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Evaluation and implementation of different time dependency schemes in a trajectory model

The TRACMASS code calculates Lagrangian trajectories in the ocean and the atmosphere off-line, i.e. after a circulation model has been integrated and the 3D velocity fields have been computed and stored. The code has two different schemes. One based on time stepping and one that solves the time dependence analytically.

The code is written in Fortran 95 and runs on unix platforms. The calculated trajectories describe passive advection of particles and are used in studies of the ocean and the atmosphere circulation in order to answer questions ranging from the global climate change to pollution in the Baltic Sea.
The students will need to have good knowledge of finite differences and will do the programming in Fortran 90.

In the present project the students will compare the two TRACMASS trajectory schemes with a Runge-Kutta trajectory scheme.
This will be done by doing the following tasks:

1) Compare the results from the TRACMASS code and the Runge-Kutta code by using a simple analytical velocity field. Find out which scheme is more accurate, and other advantages and disadvantages of the schemes. Both the time-step version of the time analytical version TRACMASS should be tested.

If the time permits, there are additional optional tasks:

2) The provided Runge-Kutta code is of the second order accuracy. Implement a 4th order Runge-Kutta scheme in this code.

3) Evaluate this 4th order Runge-Kutta scheme compared to the other schemes in the same way as in task 1.

4) Suggest how a possible implementation of the Runge-Kutta schemes could be implemented in the TRACMASS code.

Uppdaterad  2010-02-19 11:59:49 av Maya Neytcheva.