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Climate Options

This page explains every option in Climate Options for WEPPcloud end users:

  • what each option is best for,
  • what climate data it uses,
  • where that data is available,
  • how station selection modes work,
  • how CLIGEN uses .par and .prn files,
  • when to use each spatial mode,
  • what each advanced option does and when to use it.

Where to find this in WEPPcloud

  1. Open your run.
  2. Open Climate Options.
  3. Choose a climate dataset, station selection mode, and (if available) spatial mode.
  4. Expand Advanced options only when you need to tune behavior.

Opinionated recommendations

If you want the shortest defensible answer instead of a full option review:

  • For probability/risk assessments, start with Stochastic PRISM Modified.
  • For historical modeling, start with Observed DAYMET (GRIDMET wind).

Climate Datasets (Each Climate Option)

Vanilla CLIGEN

Suitable for

  • Long-term stochastic (probability/risk) analysis.
  • Baseline climate generation when you do not need a specific observed historical sequence.

Recommendation

  • Use this when you explicitly want plain CLIGEN behavior.
  • If your main goal is a probability/risk assessment and Stochastic PRISM Modified is available, prefer that option instead.

Data it uses

  • CLIGEN station statistics from the selected station.
  • Your selected simulation length (Number of years to simulate).

Where available

  • Broadly available across interfaces/locales.

Station selection modes available

  • Auto (-1), Distance ranking (0), Multi-factor ranking (1).

Spatial modes available

  • Single (0), Multiple (1).
  • Interpolated multiple (2) is not available for this dataset.

Notes

  • In Multiple mode, WEPPcloud applies a PRISM revision routine to create per-hillslope climates.

Stochastic PRISM Modified

Suitable for

  • Recommended default for probability/risk assessments.
  • Stochastic runs where you want PRISM-adjusted climate behavior.
  • BAER-style risk/probability workflows when strict historical replay is not required.

Recommendation

  • Start here when your question is probabilistic: "What is the range of likely runoff/erosion response over many possible years?"
  • Prefer this over observed historical modes when you are not trying to reproduce a specific real-world period.

Data it uses

  • CLIGEN station source + PRISM-informed adjustment workflow.
  • Stochastic simulation years you choose.

Where available

  • Available in many U.S.-centric contexts.
  • Blocked in locales configured as GHCN-only in current catalog (au, alaska, hawaii, nigeria).

Station selection modes available

  • Auto (-1), Distance ranking (0), Multi-factor ranking (1).

Spatial modes available

  • Single (0), Multiple (1).

Notes

  • Marked RAP-compatible in the current catalog.
  • In Multiple mode, PRISM revision generates per-hillslope climate files.

Observed DAYMET (GRIDMET wind)

Suitable for

  • Recommended default for historical modeling.
  • Historical/observed-condition calibration.
  • Streamflow and disturbance-validation work where observed weather is preferred.

Recommendation

  • Start here when you want to model a real historical period rather than a stochastic climate sequence.
  • This is the opinionated first choice for hindcasting, calibration, and other observed-period analyses.

Data it uses

  • DAYMET observed daily climate.
  • Optional GRIDMET wind fill (when Use GRIDMET wind when applicable is enabled).

Where available

  • Year window in catalog metadata: 1980 to 2024.
  • Blocked in GHCN-only configured locales (au, alaska, hawaii, nigeria).

Station selection modes available

  • Auto (-1), Distance ranking (0), Multi-factor ranking (1).

Spatial modes available

  • Single (0), Multiple (1), Multiple Interpolated (2).

Notes

  • In Multiple mode (1), PRISM revision is applied after base build.
  • In Multiple Interpolated mode (2), build is routed to the DAYMET interpolated hillslope workflow (no PRISM revision step in that branch).
  • Marked RAP-compatible in the current catalog.

Observed GRIDMET

Suitable for

  • Historical/observed-condition modeling using GRIDMET.
  • Workflows where observed wind/radiation/dewpoint fields from GRIDMET are desired.

Recommendation

  • Use this when you specifically want GRIDMET-native observed fields or need to compare sensitivity against DAYMET.
  • If you want one default historical option, prefer Observed DAYMET (GRIDMET wind) first.

Data it uses

  • GRIDMET observed daily climate fields.
  • Observed year window you provide.

Where available

  • Catalog description: 1980 to present.
  • Blocked in GHCN-only configured locales (au, alaska, hawaii, nigeria).

Station selection modes available

  • Auto (-1), Distance ranking (0), Multi-factor ranking (1).

Spatial modes available

  • Single (0), Multiple (1), Multiple Interpolated (2).

Notes

  • In Multiple mode (1), PRISM revision is applied after base build.
  • In Multiple Interpolated mode (2), build uses the GRIDMET interpolated hillslope workflow.
  • Marked RAP-compatible in the current catalog.

DEP NEXRAD Breakpoint

Suitable for

  • Observed breakpoint-style climate workflows where high-resolution breakpoint data is required.
  • Cases where you may want to override daily variables with PRISM/GRIDMET/DAYMET options.

Data it uses

  • DEP Mesonet breakpoint climate retrieval by centroid/hillslope coordinates.
  • Optional daily-variable overrides:
    • PRISM (tmax, tmin, tdew)
    • GRIDMET (tmax, tmin, rad, tdew, w-vl, w-dir)
    • DAYMET (tmax, tmin, rad, tdew)

Where available

  • Help text indicates 2007 to present coverage.
  • Blocked in GHCN-only configured locales (au, alaska, hawaii, nigeria).

Station selection modes available

  • Auto (-1), Distance ranking (0), Multi-factor ranking (1).

Spatial modes available

  • Single (0), Multiple (1).

Notes

  • Not marked RAP-compatible in the current catalog.

Future CMIP5

Suitable for

  • Climate-change impact analysis using projected (not historical observed) climate forcing.

Data it uses

  • CMIP5/RCP8.5 timeseries retrieval.
  • CLIGEN station + generated observed-style .prn -> .cli workflow.

Where available

  • Blocked in GHCN-only configured locales (au, alaska, hawaii, nigeria).
  • Future-year inputs are constrained in code to 2006 to 2099.

Station selection modes available

  • Auto (-1), Distance ranking (0), Multi-factor ranking (1).

Spatial modes available

  • Single (0), Multiple (1).

Notes

  • Labeled experimental in current help text.
  • Not marked RAP-compatible in the current catalog.

User-Defined Climate (.cli)

Suitable for

  • Research and validation runs where you already have a vetted CLIGEN .cli file.

Data it uses

  • Your uploaded .cli file.

Where available

  • Generally available as a user-exposed dataset.

Station selection modes available

  • User-defined (4) only.

Spatial modes available

  • Single (0), Multiple (1).

Notes

  • In this mode, Upload .cli is the primary action.
  • Climate build button behavior differs from other modes (upload-driven flow).
  • If spatial mode is Multiple, PRISM revision is applied after upload processing.

E-OBS Modified (Europe)

Suitable for

  • European observed-climate workflows.

Data it uses

  • E-OBS-based modified climate build path for EU locales.

Where available

  • EU-only (allowed_locales = eu).

Station selection modes available

  • Auto (-1), Distance ranking (0), Multi-factor ranking (1), EU heuristic (2).

Spatial modes available

  • Single (0), Multiple (1).

Notes

  • Default spatial mode is Multiple in current catalog metadata.
  • Not marked RAP-compatible in current catalog.

Region/System-Managed Climate Options

These catalog options exist in code but are not normally exposed in the standard Climate Options dataset picker:

  • Observed Climate Database (observed_db, mode 6)
  • Future Climate Database (future_db, mode 7)
  • AGDC (Australia) (agdc, mode 10)

These are ui_exposed=False in the current catalog and are primarily system/configuration driven.

Station Selection Mode

Station selection mode controls how WEPPcloud chooses or ranks station candidates for the selected dataset.

Auto (-1)

What it does

  • Uses FindClosestAtRuntime behavior.
  • The station dropdown is not actively refreshed from ranking endpoints in this mode.

When to use

  • Default workflow when you do not need to inspect or force ranked station choices.

Where available

  • Most non-user-defined datasets.

Distance ranking (0)

What it does

  • Calls the closest-stations endpoint and ranks candidates by distance to the watershed centroid.

When to use

  • When nearest-station proximity is your primary criterion.

Where available

  • Most standard datasets and several system-managed datasets.

Multi-factor ranking (1)

What it does

  • Calls heuristic station ranking.
  • For eu locale this routes to EU heuristic logic; for au locale it routes to AU heuristic logic.

When to use

  • When representativeness is more important than pure distance.

Where available

  • Available where the selected dataset includes station mode 1.

EU heuristic (2)

What it does

  • Uses the dedicated EU heuristic endpoint.

When to use

  • European runs where explicit EU heuristic ranking is desired.

Where available

  • In the current catalog, effectively tied to E-OBS Modified (Europe).

AU heuristic (3)

What it does

  • Dedicated AU heuristic endpoint exists in backend.

When to use

  • Australia-specific heuristic ranking (advanced/specialized contexts).

Where available

  • Backend supports it, but current shipped dataset metadata does not generally expose mode 3 directly.
  • In au locale, multi-factor mode (1) already routes to AU heuristic search logic.

User-defined (4)

What it does

  • Used with uploaded user-defined .cli workflows.
  • Station list refresh is skipped and station select options are cleared in that flow.

When to use

  • When supplying your own climate file.

Where available

  • User-Defined Climate (.cli) dataset.

Tenerife-specific station mode constraints

When a run uses the Tenerife station catalog (tenerife_stations.db), runtime constraints intentionally narrow options:

  • Supported dataset options are reduced to vanilla_cligen and user_defined_cli.
  • Station modes are reduced to:
    • (-1, 0) for vanilla_cligen
    • (4) for user_defined_cli
  • Unsupported climate/spatial/station combinations are rejected by backend validation.

How CLIGEN Uses .par and .prn Files

CLIGEN is the weather engine that produces the .cli file WEPP uses.

.par files

A station .par file stores long-term monthly climate statistics (for example mean precipitation, wet/dry transition probabilities, and monthly temperature arrays). In WEPPcloud:

  • Your station selection resolves to station metadata that includes the .par path.
  • The Station PAR preview panel in Climate Options shows the active station .par contents.

.prn files in observed workflows

In observed modes, WEPPcloud typically:

  1. Builds daily observed series from a source dataset.
  2. Writes those daily values into CLIGEN .prn format.
  3. Calls CLIGEN run_observed(...) to generate the final .cli.

This pattern is used across observed DAYMET, observed GRIDMET, PRISM-observed style paths, SNOTEL-support paths, and interpolated observed workflows.

Input file specifications

Spatial Climate Modes

Single climate (0)

What it does

  • Builds one climate for the watershed.

When to use

  • Fastest option.
  • Good default for many small-to-medium watersheds.

Multiple climates (1)

What it does

  • Produces per-hillslope climate outputs.
  • For many modes, this applies the PRISM revision routine after base climate build.

What PRISM revision does (plain language)

  • Retrieves PRISM ppt, tmin, and tmax rasters for the watershed extent.
  • Computes watershed-level monthly values and hillslope-level monthly values.
  • Revises the base climate to hillslope-specific climates using monthly precipitation scaling plus monthly temperature offsets.

Multiple climates (Interpolated) (2)

What it does

  • Uses dedicated interpolated observed-climate build paths.
  • Supported only for observed DAYMET / observed GRIDMET mode families (ObservedPRISM / GridMetPRISM).

When to use

  • When spatial heterogeneity is important and you are on supported observed modes.

Performance and practical guidance

  • Slower than Single.
  • In operator experience, this mode has produced some of the best calibrated results for certain Pacific Northwest watersheds.
  • It is often a strong candidate for larger watersheds or watersheds with micro-climate variation.
  1. Start with Single for speed and first-pass calibration.
  2. Move to Multiple when hillslope-scale variation appears important.
  3. Try Multiple Interpolated on supported observed modes when you need higher spatial climate fidelity and can afford extra runtime.

Advanced Options

Advanced options are visible for non-Tenerife station-catalog workflows.

Use GRIDMET wind when applicable

Function

  • Toggles the run-level use_gridmet_wind_when_applicable behavior.

Purpose

  • Injects GRIDMET wind fields for observed workflows that require wind support.

Recommended use cases

  • Enable when observed mode requires wind forcing and GRIDMET wind is appropriate.

Adjust MX .5 P Values

Function

  • Toggles adjust_mx_pt5 behavior during CLIGEN observed processing.

Purpose

  • Scales monthly MX .5 P intensity values based on observed/localized monthly precipitation ratio logic.

Recommended use cases

  • When station-normal intensity assumptions appear mismatched with your local observed precipitation behavior.

Important behavior details

  • Scaling is constrained in code (clamped to a bounded factor range).
  • Very low-precipitation months can be skipped by adjustment logic.

Post-CLIGEN precipitation scaling modes

No scaling (0)

Function/Purpose

  • No precipitation scaling is applied after build.

Recommended use case

  • Baseline control runs.

Scalar scaling (1)

Function/Purpose

  • Applies one scalar multiplier (precip_scale_factor) to precipitation.

Recommended use case

  • Fast sensitivity analysis (for example +/- 10%).

Monthly scaling (2)

Function/Purpose

  • Applies 12 month-specific multipliers.

Recommended use case

  • Seasonal bias correction.

Reference scaling (3)

Function/Purpose

  • Derives monthly scaling from a selected reference dataset (prism, daymet, or gridmet) over your observed year window.

Recommended use case

  • Aligning generated precipitation totals with an external gridded climate reference.

Important constraints

  • For PRISM reference scaling, start year must satisfy PRISM availability constraints in validation.

Spatial scaling from map (4)

Function/Purpose

  • Uses a scale-factor raster map path to apply spatially varying precipitation scaling.

Recommended use case

  • Advanced workflows with vetted external scale-factor maps.

Important constraints

  • Map path must exist.
  • Out-of-range scale factors are skipped.
  • In current UI this option is present but disabled/read-only for most users.

Practical tuning guidance

  1. Change one advanced setting at a time.
  2. Rebuild climate and rerun WEPP.
  3. Compare calibration metrics after each change.
  4. Record the setting change and rationale for reproducibility.