# Persistence, 1 degree

Holds the most recent analysis constant at every lead hour, on a 1 degree
global grid (181 x 360, pole to pole inclusive, longitude 0-360).

Input is a 0.25 degree analysis; the 1 degree grid is a strict subset of it, so
the model selects the collocated points rather than interpolating. No values are
invented.

Output is `temperature_2m` in Kelvin, shaped `(lead, lat, lon)`, at 6-hourly
steps to +168h.

## Why persistence

Persistence is the standard reference forecast in meteorology. It is trivial to
compute and its error curve is known in advance -- small at short leads, growing
steadily -- which makes it useful as a skill floor and as a check that a scoring
pipeline is behaving.

## Files

- `predict.py` -- `run(inputs, declaration, init_time)`
- `earthboi.yaml` -- the declaration: variables, lead hours, grid

## Licence

MIT.