Inconsistent zeta and w in two-way nesting - bug or irrelevant?
When I activate 2-way nesting, erroneous horizontal circulation (appearing in the time-mean) appears at certain parts of the boundary of my child domain as reported by Vincent, as well greatly (100x) amplified surface-intensified vertical velocities across the area the child domain occupies within the parent grid and a serious SSH discontinuity across the parent-child interface. The vertical velocities and SSH anomalies do not appear within the child grid itself (i.e. croco_his.nc.1), only within the area occupied by the child domain in the parent grid. This issue appears to be entirely related to 2-way nesting being activated - it is not affected by bottom-friction, timestep, resolution, boundary sponging, or initial conditions, and is not present when 1-way nesting is active. What perplexes me is that such a significant SSH discontinuity, if actually in the model, should generate geostrophic currents - but if you ignore the child domain within the parent grid, the solution looks perfect and continuous.
The fix suggested in the other thread (defining AGRIF_UPDATE_DECAL) removes the erroneous horizontal currents at the boundary, but it does not solve the vertical velocities/SSH. So my two questions are as follows:
1) Is it possible that there's a bug dumping incorrect SSH/w fields for the area occupied by the child domain in the parent grid?
2) Or, are perturbations within the child domain in the parent grid unable to propagate across the child-parent domain interface (and if so, why?)
Figures:
Zeta:
W: (scale goes up to 1E-4 m/s, actual vertical velocities in the child-domain can exceed 1E-2m/s - despite this, the model is stable and returns sensible solutions for other parameters)
