Investigate Aircraft Vertical Velocity in the prepobs code

[nicholasesposito]

Aircraft Vertical Velocity (AVV) is a variable derived in the prep code and is necessary for the bias correction Tasks:

• [x] Investigate the derivation in the prep code.
• [x] Convert the derivation code (pspl.f90, sub2mem_mer.f, pietc.f90)
• [ ] Generate an IODA file (issue #652)
• [ ] Make the AVV code run with the IODA converter. Undecided if it will be separate from the converter or part of it.
• [ ] compare the output to the aircraft prepbufr. The AVV will need to be comparable to the instantaneousAltitudeRate variable in the aircraft prepbufr.

[nicholasesposito]

I received some documents from Jim Purser about splining and the theory behind it, which I reviewed. I'm currently in the middle of converting the pspl.f and sub2mem_mer.f90 files to python. Once they're as close to completion as I can make them, I'll finish the aircft/aircar converter, then put it all together and try to run it, and debug from there.

[nicholasesposito]

• pspl.f90 has been converted to python. Variables like u0,u1, etc from pietc.f90 that were used by pspl.f90 have been replaced with their actual values (meaning u0, u1 etc) will not be found in the python converter and instead are replaced with 0, 1, or whatever they represented. Certain variables like halfgate are still in it though.
• Certain functions in pmat2.f90 have been converted to python
• I initially converted orders.f from NCEPLIBS-w3emc to python.
• sub2mem_mer.f has been partially converted. The initial code uses a lot of multi-dimension variables, but the python converter will not. I'm going to try to re-write this code in a way that uses 1D arrays.

The tasks in the first comment will be updated 2/8 with the work expected.