Update calibration coefficients to PATMOS-X version 2023

[sfinkens]

Update calibration coefficients to PATMOS-X version 2023.

Source: https://cimss.ssec.wisc.edu/patmosx/calibration/

I've declared them "provisional", because MetOp-B visible channels are degrading and the PATMOS team is investigating the issue. Service alert by EUMETSAT from 2023-08-15 (https://uns.eumetsat.int/?filter=metopbavhrr):

AVHRR channel 3A (1.61 microns) reached its Signal to Noise Ratio limit of 20:1 with a trend to further degradation. Furthermore, the other Near Visible channels 1 and 2 are also degrading.

Edit: As requested by @kgkarl I set S1=0.1 for channel 3a on NOAA-15 (instead of zero). So pygac can at least produce finite results for the small periods where channel 3a is active. This deviates from the original PATMOS coefficients.

[sfinkens]

@kgkarl If you have time, please review the changes :slightly_smiling_face:

[codecov[bot]]

Codecov Report

Merging #124 (cbf2d7c) into main (a8b68a3) will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #124   +/-   ##
=======================================
  Coverage   74.39%   74.39%           
=======================================
  Files          32       32           
  Lines        2882     2882           
=======================================
  Hits         2144     2144           
  Misses        738      738           

Files Changed	Coverage Δ
pygac/calibration.py	94.73% <ø> (ø)
pygac/tests/test_calibrate_klm.py	100.00% <100.00%> (ø)
pygac/tests/test_calibrate_pod.py	100.00% <100.00%> (ø)