CFS_Reforecast_FX

class earth2studio.data.CFS_Reforecast_FX(

cache=True,

verbose=True,

async_timeout=600,

async_workers=16,

retries=3,

)

Global

NCEP CFSv2 6-hourly 9-month reforecast (pressure-level product).

The CFS reforecast is a 30-year offline integration of CFSv2 produced by NCEP to support training and bias-correction of the operational system. Cycles are launched every 5 days from 1981-12-12 to 2011-03-27; each 5-day cycle directory contains four 6-hourly initial conditions (00/06/12/18 UTC) integrated forward to roughly 9 months in 6-hour steps. Only ensemble member 01 of the operational 1-4 set is published in this 9-month series.

This class exposes the pressure-level (pgbf) product on the same 1 degree regular lat-lon grid (181 x 360) as the operational CFS_FX. Variable definitions are taken verbatim from CFSLexicon, which the grib2 inventories match.

Parameters:

• cache (bool, optional) – Cache data source on local memory, by default True. Cached files are large (~22 MB per (IC, lead) pgbf file) and are reused across variable requests for the same file.

• verbose (bool, optional) – Print download progress, by default True.

• async_timeout (int, optional) – Total timeout in seconds for the entire fetch operation, by default 600.

• async_workers (int, optional) – Maximum number of concurrent async fetch tasks, by default 16. Each task downloads one whole grib file.

• retries (int, optional) – Number of retry attempts per failed fetch task with exponential backoff, by default 3.

Warning

This is a remote data source and can potentially download a large amount of data to your local machine for large requests. Unlike the operational archive, the reforecast bucket has no .idx companions; every variable request triggers a full grib-file download (~22 MB) if not already cached.

Note

The reforecast 9-month series only publishes ensemble member 01; no member constructor argument is exposed.

Note

Additional information on the data repository:

• https://www.ncei.noaa.gov/products/weather-climate-models/climate-forecast-system

• https://www.ncei.noaa.gov/data/climate-forecast-system/access/reforecast/6-hourly-by-pressure-level-9-month-runs/

• https://www.ncei.noaa.gov/data/climate-forecast-system/access/reforecast/6-hourly-flux-9-month-runs/

__call__(time, lead_time, variable)

Retrieve CFS reforecast data.

Parameters:

• time (datetime | list[datetime] | TimeArray) – Initial-condition timestamps to return data for (UTC).

• lead_time (timedelta | list[timedelta] | LeadTimeArray) – Forecast lead times to fetch (6-hour increments, 0 to ~9 months).

• variable (str | list[str] | VariableArray) – Variable identifier(s). Must be in the source’s lexicon.

Returns:

CFS reforecast data array with dimensions [time, lead_time, variable, lat, lon].

Return type:

xr.DataArray

async fetch(time, lead_time, variable)

Async fetch of CFS reforecast data.

Parameters:

• time (datetime | list[datetime] | TimeArray) – Initial-condition timestamps (UTC).

• lead_time (timedelta | list[timedelta] | LeadTimeArray) – Forecast lead times.

• variable (str | list[str] | VariableArray) – Variable identifier(s). Must be in the source’s lexicon.

Returns:

CFS reforecast data array.

Return type:

xr.DataArray

classmethod available(time)

Check whether a CFS reforecast initial condition is available.

Performs offline validity checks (6-hour cycle, history range); the every-5-days cycle calendar is not enforced here because it shifts slightly across leap-year boundaries. Off-schedule requests are surfaced as FileNotFoundError at fetch time.

Parameters:

time (datetime | np.datetime64) – Initial-condition date time to check.

Returns:

Whether the offline checks pass.

Return type:

bool