Patch/pcfill

[WPringle]

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[WPringle]

@SorooshMani-NOAA @pvelissariou1 Takis, I made some changes and added this test to compare our filling results to yours for the Chavas et al. (2025) and Courtney and Knaff (2009) methods.

What I found is:

• For Chavas results they are the same (within 1 kt) of each other, just different due to rounding. The exception is if the background pressure is different (due to the filling algorithm we apply) or for the first time snap, it seems we have a different way to calculate the storm speed (we just copy the value from the second time snap at the moment I think).

• For Courtney results they are also the same much of the time, but for some time snaps they can be 8 hPa or more different. I don't know where this could come from because I checked equations, and the example time snap where the difference is larger and the values are not at any lower limit or something like that. I was thinking it could come from difference in storm speed but then I would expect that this gives a difference for Chavas results as well.

Could you run this test (tests/test_pcfill.py) from this branch and double-check yours and ours code and comparisons to see if any reason for discrepancy? Thanks