Add ABI Day Cloud Type ("cloud_type") RGB

[djhoese]

New ABI composite. Almost the exact same thing as day cloud phase distinction but different red channel.

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.18%. Comparing base (f15bd3b) to head (c5dca11).
Report is 19 commits behind head on main.

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  Coverage   96.18%   96.18%           
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  Files         391      391           
  Lines       56633    56633           
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  Misses       2162     2162           

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[coveralls]

Pull Request Test Coverage Report for Build 14538111256

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• Overall coverage remained the same at 96.286%

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Covered Lines:	54725
Relevant Lines:	56836

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💛 - Coveralls

[strandgren]

Just for your information, there is also the cimss_cloud_type RGB available in visir.yaml, but that one uses slightly different stretching and gamma. Here is the guide from Eumetrain providing the recipes for both variants: https://resources.eumetrain.org/data/7/736/navmenu.php?tab=3&page=1.0.0. I guess this is a good candidate for RGB recipe standardization during this weeks RGB workshop 😄

[gerritholl]

satpy also has a version that uses the sunz_reduced modifier (for FCI). In DWD, we have swapped this for the solar_pathlength_corrected modifier (similar to effective_solar_pathlength_corrected but with different parameters).

satpy/satpy/etc/composites/fci.yaml

Lines 317 to 331 in 0a00879

	cloud_type:
	description: >
	Equal to cimss_cloud_type recipe, but with additional sunz_reducer modifier to avoid saturation at the terminator.
	references:
	EUMETRAIN Quick Guide: https://resources.eumetrain.org/rgb_quick_guides/quick_guides/CloudTypeRGB.pdf
	Recipe: https://resources.eumetrain.org/RGBguide/recipes/RGB_recipes.pdf
	compositor: !!python/name:satpy.composites.GenericCompositor
	prerequisites:
	- name: nir_13
	modifiers: [sunz_corrected, sunz_reduced]
	- name: vis_06
	modifiers: [sunz_corrected, sunz_reduced]
	- name: nir_16
	modifiers: [sunz_corrected, sunz_reduced]
	standard_name: cimss_cloud_type

I understand sunz_corrected is already applied to ABI data, but is this reduced near the terminator in any way?

[djhoese]

I understand sunz_corrected is already applied to ABI data, but is this reduced near the terminator in any way?

VIIRS SDR has the sunz corrected applied in the reader, but not ABI. ABI requires it to be specified in the composite recipe if it is desired. And no reduction is done other than max_sza and correction_limit of the modifier class in satpy/modifiers/geometry.py.

@strandgren Thanks. Maybe I'll add that URL to this recipe. I had noticed the CIMSS variant but also that it didn't match what the CIRA/NASA/NOAA guide had. I do not like RGBs.

[mraspaud]

At the RGB workshop, it was decided this composite should be called day_cloud_type.
Also, just cloud_type can potentially conflict with the level 2 product of the same name. I wonder is satpy is smart enough to sort this out depending on the kind of input file it has.

[djhoese]

Yeah I will rename this one and I'll probably make a separate PR to rename and deprecate other RGBs for ABI. For example, convection -> day_convection.

The enhancements can be configured by "reader" so there is at least that control. I did actually need to do that in my Polar2Grid project for this RGB where Satpy was matching with a L2 product clavrx product's enhancement for "cloud_type" versus this one. I had to add "reader" to the L2 version.

Anyway...I'll try to find time for this and the other RGBs today.

[djhoese]

@mraspaud can you double check this? I think I made all the changes you requested.