Units and Conventions

All canonical half-lives are SQLite REAL values in years, including short-lived nuclides and biological retention components. The loader restores nuclide and plant half-lives as astropy.units.year quantities.

Other fixed units are encoded in column names or explicit unit columns:

• deposition velocity: m/s
• plant biomass and yield: kg fresh mass/m2
• water film: mm
• soil mass: kg/m2
• consumption/feed ration: kg/day
• inhalation: m3/h
• storage/mast duration: day
• skin area: m2
• skin retention: hour
• ingestion/inhalation factor: Sv/Bq

Days of year remain explicit calendar coordinates and are not interchangeable with durations or elapsed simulation days. LAI and biomass curve days are zero-based. Plant growth-start, harvest-start, and harvest-end scenario days, and hay preparation dates, retain the workbook's one-based 1..365 seasonal coordinates. At an event boundary the engine converts the event date to a one-based seasonal coordinate before comparing it with those fields. In a leap year the canonical seasonal March 1 date remains March 1; Gregorian elapsed time separately counts February 29. See the development history (§4.1) for the oat-harvest boundary trace.

NULL means optional/not supplied. Numeric zero remains an explicit model value. The workbook importer defaults to the historical parsing policy, which can supply defaults or omit malformed entries and records those choices as diagnostics. Strict import rejects these fallbacks. See the parameter-set guide for the bundled-workbook diagnostic baseline and the distinction between import policy and database validation.

See export_excel_data/CANONICAL_CONVENTIONS.md for the authoritative convention record.