Add the reader for the fci L1C Africa files

[ClementLaplace]

I have added the possibility to read the data for AFRICA files related to the FCI instrument for the L1C level.

• Tests added
• Fully documented
• Add your name to AUTHORS.md if not there already

[ameraner]

Thanks Clement for this nice work! I have left some comments and hints in the code.

Please also expand in the Filehandler docstring the fact that we support also the African data now, with link to the AfricaPUG.

[codecov]

Codecov Report

Attention: Patch coverage is 97.36842% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 95.95%. Comparing base (f5a8532) to head (54fbb11).
Report is 124 commits behind head on main.

Files	Patch %	Lines
satpy/readers/fci_l1c_nc.py	63.63%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2778      +/-   ##
==========================================
+ Coverage   95.94%   95.95%   +0.01%     
==========================================
  Files         379      379              
  Lines       53673    53958     +285     
==========================================
+ Hits        51494    51774     +280     
- Misses       2179     2184       +5     

Flag	Coverage Δ
behaviourtests	4.08% <0.00%> (-0.01%)	⬇️
unittests	96.04% <97.36%> (+0.01%)	⬆️

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[coveralls]

Pull Request Test Coverage Report for Build 9205754552

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 148 of 152 (97.37%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+96.0%) to 96.03%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
satpy/readers/fci_l1c_nc.py	7	11	63.64%

Totals
Change from base Build 8732515933:	96.0%
Covered Lines:	51646
Relevant Lines:	53781

---

💛 - Coveralls

[sjoro]

a general comment about the fci_l1c_nc.yaml-file. this file repeats key required_netcdf_variables 18 times under different file-types and it seems to be the same set for each file-type. has anyone tried using "anchors and aliases" in these files? that is, create anchor &required_netcdf_variables only once somewhere at the top of the file and use an alias *required_netcdf_variables where needed... should look something like:

&required_netcdf_variables:
  - attr/platform
  - data/{channel_name}/measured/start_position_row
  - data/{channel_name}/measured/end_position_row
  - data/{channel_name}/measured/radiance_to_bt_conversion_coefficient_wavenumber
  - data/{channel_name}/measured/radiance_to_bt_conversion_coefficient_a
  - data/{channel_name}/measured/radiance_to_bt_conversion_coefficient_b
  - data/{channel_name}/measured/radiance_to_bt_conversion_constant_c1
  - data/{channel_name}/measured/radiance_to_bt_conversion_constant_c2
  - data/{channel_name}/measured/radiance_unit_conversion_coefficient
  - data/{channel_name}/measured/channel_effective_solar_irradiance
  - data/{channel_name}/measured/effective_radiance
  - data/{channel_name}/measured/x
  - data/{channel_name}/measured/y
  - data/{channel_name}/measured/pixel_quality
  - data/{channel_name}/measured/index_map
  - data/mtg_geos_projection
  - data/swath_direction
  - data/swath_number
  - index
  - state/celestial/earth_sun_distance
  - state/celestial/subsolar_latitude
  - state/celestial/subsolar_longitude
  - state/celestial/sun_satellite_distance
  - state/platform/platform_altitude
  - state/platform/subsatellite_latitude
  - state/platform/subsatellite_longitude
  - time

fci_l1c_af_vis_06:
  file_reader: !!python/name:satpy.readers.fci_l1c_nc.FCIL1cNCFileHandler
  file_patterns:
    [
      "{pflag}_{location_indicator},{data_designator},MTI{spacecraft_id:1d}-{data_source}-1C-RRAD-3KM-{coverage}-VIS06-{component1}-x-{component3}-{purpose}-{format}_{oflag}_{originator}_{processing_time:%Y%m%d%H%M%S}_{facility_or_tool}_{environment}_{start_time:%Y%m%d%H%M%S}_{end_time:%Y%m%d%H%M%S}_{processing_mode}_{special_compression}_{disposition_mode}_{repeat_cycle_in_day:>04d}_{erraneous_count_in_repeat_cycle:>04d}.nc",
      "{pflag}_{location_indicator},{data_designator},MTI{spacecraft_id:1d}-{data_source}-1C-RRAD-1KM-{coverage}-VIS06-{component1}-x-{component3}-{purpose}-{format}_{oflag}_{originator}_{processing_time:%Y%m%d%H%M%S}_{facility_or_tool}_{environment}_{start_time:%Y%m%d%H%M%S}_{end_time:%Y%m%d%H%M%S}_{processing_mode}_{special_compression}_{disposition_mode}_{repeat_cycle_in_day:>04d}_{erraneous_count_in_repeat_cycle:>04d}.nc",
    ]
  expected_segments: 1
  required_netcdf_variables:
    *required_netcdf_variables
  variable_name_replacements:
    channel_name:
      - vis_06

if this works it would reduce the number of lines in the file by 400+ lines (already 2500 lines long!!) and would be easier to read and maintain.
here's a short tutorial i found:
https://batalin.dev/posts/yaml-anchors-and-aliases/

@ClementLaplace can you make a quick test and see if it works? if yes, please modify the PR accordingly.

[sjoro]

nice work @ClementLaplace ! a few comments/questions for improved(?) readability and maintainability.

[sjoro]

last nitpicks and editorial comments. thanks clement for taking care of this feature!

[sjoro]

LGTM

[mraspaud]

Nice work, especially with refactoring the tests! They are still quite intricate, but it's getting better :) some quick fixes mentioned inline, but after that it's good to merge IMO