Here a series of runs are compared where the details of the filtering strategy
are changed. All runs were performed with the Aug 2 2024 (99698724377) master
branch code, but the behavior of the filter was changed using simple hacks.
The test case is the New Zealand Deepwave case using 4 km horizontal spacing
and 1 km vertical. The entire duration of the forcing is 2 hours and the
simulation time is shifted by 8 hours in order to match with UTC time from the
observations.
The movie below shows a comparison of the vertical velocity for three cases:
(1) The stock code where the filter weights are variable in both space
and time. The stock values of the filter weight adjustment in time are also
used and these more or less prevent the weights from decreasing in time. (2) A
hacked version where the filter weights do not very in space, but do vary in
time. The filter weight adjustment parameters were also changed so that the
weights can decrease in time. (3) A hacked version where the filter weights
are constrained to be fixed in both space and time. This case should mimic
the old filtering strategy. The constant filter weight was set at 0.20, which
is close to the stability bound (the code will run with a weight of 0.175, but
visible oscillations are present in the solution).
