chelsa CHELSADaily

rslearn.data_sources.chelsa.CHELSADaily

CHELSA-daily is a global (~1km) climate dataset with one GeoTIFF per day and variable. See the official CHELSA-daily dataset page.

This data source currently targets: - URL base: https://os.unil.cloud.switch.ch/chelsa02/chelsa - Dataset path: global/daily/{variable}/{year}/CHELSA_{variable}_{dd}_{mm}_{yyyy}_V.2.1.tif - Default time range: 1979-01-01 to 2025-08-29 (inclusive)

Use query_config.space_mode = SINGLE_COMPOSITE so all matching daily items are returned in one group.

Configuration

{
  "class_path": "rslearn.data_sources.chelsa.CHELSADaily",
  "init_args": {
    // CHELSA variable names to read (if omitted, inferred from layer_config bands).
    // For precipitation, either "pr" or "prec" works: rslearn automatically
    // switches URL variable by year (before 2020 -> "pr", after 2020 -> "prec",
    // overlap year 2020 preserves your requested alias).
    "band_names": ["tas", "pr"],

    // Optional dataset bounds (inclusive). Can be date or YYYY-MM-DD string.
    // Tighten this to your actual window time range to avoid preparing extra days.
    "start_date": "2017-01-01",
    "end_date": "2025-08-29",

    // Optional AOI as [min_lon, min_lat, max_lon, max_lat].
    // With ingest=true this clips each daily GeoTIFF before storing it in the
    // tile store, avoiding explicit full-global downloads/re-encoding for local
    // projects.
    "bounds": [-8.7, 49.8, 2.1, 60.9],

    // Optional override for file naming version suffix.
    "version": "V.2.1"
  },
  "query_config": {
    "space_mode": "SINGLE_COMPOSITE"
  }
}

CHELSA-daily is distributed as global GeoTIFFs. For regional work, set bounds to the area of interest. If bounds is omitted, ingestion stores the full global source GeoTIFF for every matched day.

Precipitation Alias Handling

CHELSA daily precipitation has two variable names: - pr in years before 2020 (and also available in 2020) - prec in years after 2020 (and also available in 2020)

When you configure either precipitation alias (pr or prec), rslearn automatically chooses the URL variable for each item date so multi-year runs across the transition work without manual layer changes.

Supported Variables

Code	Name	Unit	Description
clt	Total Cloud Cover Percentage	percent	Total cloud area fraction (reported as percentage) for the full atmospheric column, including large-scale and convective cloud.
hurs	Near-Surface Relative Humidity	percent	Relative humidity with respect to liquid water for T > 0°C and with respect to ice for T < 0°C.
pr	Precipitation	kg m-2 day-1	Daily precipitation including both liquid and solid phases.
prec	Precipitation	kg m-2 day-1	Alias of CHELSA daily precipitation used in later years.
ps	Surface Air Pressure	hPa	Surface pressure (not mean sea-level pressure).
rsds	Surface Downwelling Shortwave Flux in Air	W m-2	Surface solar irradiance, commonly used for UV-related calculations.
sfcWind	Near-Surface Wind Speed	m s-1	Near-surface (usually 10 m) wind speed.
tas	Daily Mean Near-Surface Air Temperature	K	Near-surface (usually 2 m) daily mean air temperature.
tasmax	Daily Maximum Near-Surface Air Temperature	K	Near-surface (usually 2 m) daily maximum air temperature.
tasmin	Daily Minimum Near-Surface Air Temperature	K	Near-surface (usually 2 m) daily minimum air temperature.
tz	Air Temperature Lapse Rate	K m-1	Rate of change in air temperature with altitude (centennial-period lapse-rate product).