What's New

v2026.03.b1 - 30th March 2026

New Features

• Introduction of NEMODataArray object, including manual and NEMODataTree constructors:

  • NEMODataArray properties to support grid-aware computation (e.g., .mask, .metrics, .grid etc.).

  • NEMODataArray methods:

    • Masking: .apply_mask().
    • Selections: .sel_like().
    • Grid Operators: .diff(), .derivative(), .integral(), .depth_integral().
    • Statistics: .weighted_mean(), .masked_statistic().
    • Interpolation: .interp_to().
    • Grid Transformations:.transform_vertical_grid().

• Addition of .depth_integral() method to integrate a variable defined on a given NEMO model grid in depth coordinates between two depth limits.

• Addition of .weighted_mean() method to perform a grid-aware weighted mean of a variable defined on a NEMO model grid.

• Update to NEMODataTree constructors:

• NEMODataTree supports NEMO model outputs using the linear free-surface approximation (i.e., time-independent vertical scale factors) via key_linssh=True.

• Defined Pixi workspace & environments (pixi.toml) to support NEMO Cookbook development.

New Recipes

• Two additional NEMO Cookbook Recipes:
• Upper Ocean Heat Content - recipe_heat_content.ipynb
• Meridional Ocean Heat Transport - recipe_heat_transport.ipynb

Breaking Changes

• .transform_to() method to linearly interpolate a variable to a neighbouring NEMO grid renamed to interp_to().

• Using dictionary syntax to access a variable from a NEMODataTree no longer returns a land-sea masked variable. Instead, an unmasked NEMODataArray is returned, which can be subsequently masked using the .masked attribute.

• Started Deprecation Cycle for legacy NEMODataTree methods & included deprecation warnings for affected methods. These methods will be removed from NEMO Cookbook in v2026.05 later this year.

Bug Fixes

• Fix .add_geoindex() using xoak.SklearnGeoBallTreeAdapter & added xoak dependency.
• Fix .extract_section() to improve boundary indexing and add land-sea masks
• Fix nested test class TestNEMODataTreeUtils() in test_nemodatatree.py
• Fix potential NameError in create_section_polygon() where section endpoints share same latitude.
• Fix TypeError (keep_dims=None) in compute_binned_statistic() in stats.py.
• Fix alignment error in interpolate_grid() utility function.

Documentation

• Reorganise User Guide to add NEMO Fundamentals section and improve NEMODataArray description.
• Update contributing guidance in docs to add getting started with Pixi & GitHub.
• Add .ipynb template and GitHub Issue template for NEMO Cookbook recipes.
• Update How To... guide to include NEMODataArray usage.

Full Changelog: https://github.com/NOC-MSM/nemo_cookbook/compare/v2026.01.0b1...v2026.03.0b1

v2026.01.b1 - 18th January 2026

New Features

• Introduction of NEMODataTree object, including .from_paths() and .from_datasets() constructors.
  • NEMODataTree methods to calculate model grid cell properties (e.g., .cell_area()).
  • NEMODataTree methods to perform grid-aware scalar and vector operations (e.g., .gradient(), .integral().
  • NEMODataTree methods to calculate grid-aware masked and binned statistics (e.g., .masked_statistic(), .binned_statistic())
  • NEMODataTree methods to transform model grid coordinates (e.g., .transform_to())

New Recipes

• NEMO Cookbook Recipes, including
  1. Meridional overturning stream function in an arbitrary tracer coordinates.
  2. Meridional overturning stream function in depth coordinates (z/z*).
  3. Meridional heat & salt transports.
  4. Surface-forced water mass transformation in potential density coordinates.
  5. Volume census in T-S coordinates.
  6. Masked statistics using bounding boxes and polygons.
  7. Extracting volume transports and properties along the Overturning in the Subpolar North Atlantic array.
  8. Vertical coordinate transformations.
  9. Barotropic stream functions.

Full Changelog: https://github.com/NOC-MSM/nemo_cookbook/commits/v2026.01.0b1