Review Land Variables Mapping for CMIP7

[rbeucher]

This pull request introduces several improvements and new features to the land and vegetation fraction calculations in the access_moppy derivations module. The changes enhance support for CMIP compliance by converting outputs to percentages, add new generalized mass pool calculations, and improve documentation and usability for vegetation-type handling. The most important changes are grouped below:

Land and vegetation fraction calculations:

• The extract_tilefrac function now outputs tile fractions as percentages (0-100%), supports an optional vegetation type dimension for CMOR character-type variables, and provides improved documentation, error handling, and vegetation type mapping. [1] [2]
• The calc_landcover function has been updated to output land cover fractions as percentages and to include descriptive vegetation type labels for both CABLE and CMIP6 models, with expanded documentation and examples. [1] [2]

Generalized mass pool calculations:

• Added new functions: calc_mass_pool_kg_m2, calc_carbon_pool_kg_m2, and calc_nitrogen_pool_kg_m2 for generalized calculation of mass pools (carbon, nitrogen, etc.) with tile weighting, spatial integration, and unit conversion to kg m-2. [1] [2] [3]
• Added calc_cland_with_wood_products for calculating total land carbon including wood products with proper weighting and conversion. [1] [2] [3]

API and naming changes:

• Deprecated average_tile in favor of the new weighted_tile_sum function, which provides clearer semantics for tile-weighted calculations. [1] [2] [3]

[codecov]

Codecov Report

❌ Patch coverage is 14.20613% with 308 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.17%. Comparing base (bc36128) to head (ec6dbef).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/access_moppy/utilities.py	4.93%	212 Missing ⚠️
src/access_moppy/base.py	27.63%	55 Missing ⚠️
src/access_moppy/derivations/calc_land.py	27.27%	16 Missing ⚠️
src/access_moppy/atmosphere.py	22.22%	14 Missing ⚠️
src/access_moppy/driver.py	42.10%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #161      +/-   ##
==========================================
- Coverage   57.55%   52.17%   -5.39%     
==========================================
  Files          18       18              
  Lines        2403     2739     +336     
==========================================
+ Hits         1383     1429      +46     
- Misses       1020     1310     +290     

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