Roadmap#

Note

PYSTILT is alpha software (the 0.1.0a series). The public API may change between releases until v1.0.

Current status#

These parts are stable and covered by the test suite:

HYSPLIT trajectories and footprints
Footprints that match uataq/stilt (STILT-R) at rtol=1e-7 per cell
Running locally and on Slurm
Reruns that skip finished simulations, judged by which output files exist
Variants, which run the same receptors under several named settings in one project. Transport-error ensembles and extra footprints are variants too.
Helpers for column and satellite observations

Footprints can also be summed onto other geometries. A footprint is computed on a rectangular grid and then summed onto a stilt.Grid, a stilt.Mesh (from shapefiles, H3 hexagons, or windows around points), or stilt.Zones (groups of cells), using cached overlap weights. Grid.from_geometry picks a grid for a geometry, the geometry footprint setting names one in YAML, and Trajectories.footprint makes new footprints from saved particles.

Most new work is on column and slant-column workflows for satellite and ground-based instruments (see Future plans below). The execution and service code is maintained but not growing.

Execution and orchestration (from stiltctl)#

stiltctl runs STILT on cloud infrastructure. PYSTILT uses the same call path. The CLI calls Model, and Model hands the work to an execution backend.

Feature	Status
Pull-mode queue workers (`stilt pull-worker`)	Implemented
Long-lived streaming mode (`stilt serve`)	Implemented
PostgreSQL-backed work queue for distributed coordination	Implemented
Thin CLI → `Model` → worker call path	Implemented
Kubernetes worker deployment	Partial
Cloud object store outputs (GCS, S3)	In scope

Column and satellite science (from X-STILT)#

X-STILT extends STILT for column and slant-path satellite retrievals. PYSTILT ports X-STILT’s ideas for handling observations and weighting columns. It does not try to match every X-STILT feature.

Feature	Status
`stilt.observations` helpers (overpass grouping, sounding selection, jitter, slant geometry)	Implemented
Column receptor support	Implemented
Averaging-kernel and pressure-weighting particle transforms	Implemented
First-order lifetime decay transform	Implemented
Declarative transforms in config YAML (default or per variant)	Implemented
Slant-column receptor support	Implemented (see the Slant Columns guide)
Slant altitudes from a retrieval’s pressure levels (`pressure_altitudes`)	Implemented
User-defined transforms via `kind: my.module.Class`	Implemented
Per-sounding averaging kernels in batch runs (`averaging_kernel` with `table:`)	Implemented
Product readers (OCO-2/3, TROPOMI, TCCON)	Implemented (see Reading Retrieval Products); other instruments as one module each
Transport error on the modelled enhancement (`transport_error`)	Implemented
Modelled enhancement from a flux field (`Footprint.enhancement`)	Implemented
Background from a mole-fraction field at the trajectory endpoints (`background`)	Implemented
Satellite-derived plume background (forward trajectories)	Implemented (see the Plume Background guide)
Forward runs (positive `n_hours`) for plume and dispersion studies	Implemented (see the Plume Background guide)
Emission-error propagation to the modelled enhancement	A recipe on `Footprint.enhancement` (see the Transport Error guide); the correlated case is fips’s `prior_obs_error`
Inventory readers	Out of scope; a flux field is an xarray array

Future plans#

In priority order:

Readers for the instruments people bring, such as EM27/SUN and MethaneAIR/MethaneSAT. Which ones come first depends on who is using column receptors.
A YAML form for stilt.Zones, so the geometry footprint setting can name groups of cells.