Boundary treatment

[juan-park]

Line 92 of tracker.py is
I = grid.atsea(X1, Y1)
shouldn't it be
I = grid.onland(X1, Y1)?

[bjornaa]

This works as supposed.

The old particle position is (X, Y) while (X1, Y1) is the candidate for the new particle position.
Line 92 is the final check, if the (X1, Y1) is at sea it becomes the new position.
If the position is on land, it does not move i.e. (X, Y) is retained as the new position.

In lines 77+ the opposite logic is used. If the new position is outside the grid, X1 is replaced by
the old position X. This is inconsistent coding and may be confusing. This will be cleaned up in the
next revision of the code.

Another issue is if this is the best way to handle the land boundary. I plan to include different options. For some applications, like pollution transport, it may be better to let the particle move onto land and become stranded.

Bjørn