# Petrel Fuel — Layers — release notes

Rolling version history for the Petrel Fuel **Layer** — the Scott & Burgan 40
(FM40) surface fuel-model class at native ~270 m (9 arcsec) globally, from a
deterministic land-cover × climate crosswalk. Newest release first.

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## v1.0 · 2026-08

- **Initial release.** A global Scott & Burgan **FM40 surface fuel-model class**
  raster at **native ~270 m (9 arcsec)**, assigned deterministically from ESA
  WorldCover 2021 land cover × Beck Köppen-Geiger climate: land cover sets the
  fuel family (non-burnable / grass / grass-shrub / shrub / timber-understory /
  timber-litter) and climate refines it (e.g. Mediterranean shrub → SH5,
  tropical forest → TL9, boreal forest → TU5). Feeds the surface-fuel grid of
  the Petrel Wildfire Hazard (Cell2Fire), and works standalone for fuels mapping
  and fire-behavior work.
- **Free and commercial-clean (CC-BY-4.0).** This is the whole point of v1.0: it
  derives only from CC-BY-4.0 sources — no Meta canopy (CC-BY-NC), no LANDFIRE,
  no share-alike inputs — so it is fully **commercially redistributable** with
  attribution. It **replaces the earlier CC-BY-NC ML fuel line**
  (`fuel_v0.1/v0.2_global_ml`) as the free fuel layer.
- **Globally consistent by construction.** The crosswalk applies the same rules
  everywhere, fixing the US-trained ML line's abroad errors — Mediterranean
  shrub read as grass, tropical/boreal forest families confused, and open water
  read as grass are all corrected.
- **Class only in v1.0.** Ships the FM40 class raster; the four canopy
  attributes (cover, stand height, canopy base height, bulk density) are a
  documented **v1.1** item (real per-pixel values from the CC-BY ETH global
  canopy-height layer). Validation is biome plausibility plus US LANDFIRE
  family agreement — not a per-pixel accuracy score.