G-P19 · TOPIC · reproducible-modellingGCRI dossier · service level R0
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Topic dossier · Systems Science and Modelling

Reproducible modelling

A model result should be reproducible: others should be able to rerun the model with the same code, data and settings and get the same result, and inspect every step. Many published models cannot be rerun because code, data or environments are missing. This page sets out how reproducible modelling is practised, how it is checked, and what evidence serves the modellers, publishers and institutions who depend on it.

01In brief

The short answer.

Reproducible modelling is the practice of making model results rerunnable and inspectable by others, using the same code, data and settings. It depends on archived code and inputs with identifiers, recorded software environments, workflows that record every step and versioning that lets corrections be traced.

02Geography

Hazards and exposure in North America.

For reproducible modelling, in GCRI's spatial-intelligence reading, the map opens on true-colour imagery, land cover and night lights with relief in 3D, framed on North America; every other NASA layer, live feed and forecast waits in the layer list.

The interactive map needs JavaScript; the layer list and sources are below.

Layers 3

Hazards and exposure, for this page

Latest available

NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth

Loading the latest NASA imagery.

Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.

For reproducible modelling, in GCRI's spatial-intelligence reading, the map opens on true-colour imagery, land cover and night lights with relief in 3D, framed on North America; every other NASA layer, live feed and forecast waits in the layer list.Satellite and model products as NASA publishes them, each with its own date; indicators, not assessments of any place; claim ceiling INTEGRATED.

Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONET · GDACS · Copernicus Sentinel-2 L2ASources and licences

  • We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • VIIRS Black Marble night-time lights, NASA Goddard Space Flight Center; distributed by the NASA Level-1 and Atmosphere Archive and Distribution System (LAADS DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • Center for International Earth Science Information Network (CIESIN), Columbia University. 2018. Gridded Population of the World, Version 4 (GPWv4): Population Density, Revision 11. NASA Socioeconomic Data and Applications Center (SEDAC). Licensed under CC BY 4.0. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). CC BY 4.0
  • GPM IMERG precipitation, NASA Precipitation Processing System; distributed by the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
  • © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). ODbL
  • Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
  • Globe: MapLibre GL JS 6.9.1, BSD-3-Clause, © MapLibre contributors.
  • Live: NASA EONET Events are indicative, not official warnings.
  • Live: GDACS (EC JRC / UN OCHA) Events are indicative, not official warnings.
  • Observed (EO): Copernicus Sentinel-2 L2A (contains modified Copernicus Sentinel data 2026), Microsoft Planetary Computer
  • Optional layers (35 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.

Layers and dates

  • True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
  • Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
  • Night-time lights, daily: VIIRS Black Marble (VNP46A2), NASA LAADS DAAC · 12 Oct 2026
  • Population density, 2020: Population: CIESIN, Columbia University, Gridded Population of the World v4.11 (2018), NASA SEDAC, CC BY 4.0 · static
  • Flood water, 3-day composite: VIIRS Global Flood Product, NASA LANCE · 14 Oct 2026
  • Precipitation rate, daily mean: GPM IMERG, NASA GES DISC · 12 Oct 2026

03The question

Reproducible modelling: how the risk develops.

Versioned models, data lineage and re-runnable results. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.

Mechanism

Code and data must be available

Without the exact code and inputs, a result cannot be checked. Archiving them with identifiers makes reruns possible.

Mechanism

Environments decay

Software dependencies change over time. Recording environments with containers or lock files keeps models runnable for longer.

Mechanism

Workflows record steps

Workflow tools record every step from raw data to final figures, removing undocumented manual steps from the chain.

Mechanism

Versioning supports correction

When errors are found, versioned models and data let corrections be traced and affected results updated.

04Key terms

Terms used on this page.

Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.

TermDefinition
Computational reproducibilityObtaining the same results by rerunning the same code on the same data in the same environment.
Lock fileA file recording the exact versions of software dependencies used.
Research softwareSoftware created for or used in research, such as models and analysis code.
05Indicators

What is measured, and how well.

Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.

IndicatorUnitCadenceSource typeLabel
Models with archived codepercent of published modelsper reviewCode archive checksOBSERVED
Successful independent rerunspercent of attempted rerunsper auditReproduction studiesOBSERVED
Models with recorded environmentspercentper reviewRepository checksOBSERVED
Software with persistent identifierscountannualArchive recordsOBSERVED
Corrections issuedcount with reasoncontinuousCorrection logsOBSERVED
Models meeting FAIR4RS criteriapercentper assessmentFAIR assessmentESTIMATED
06Canvas

From sources to decisions.

The topic as a computational graph: named sources feed the methods, an evidence review gates the outputs, and the decisions stay with the authorities that hold them.

Pipeline canvas · Reproducible modelling as a run graphDesign, not a record
Reproducible modelling: build, test and release in Nexus FoundryA request opens a workspace; data are ingested and validated; the model is built and tested on held-out data; an independent gate approves release with limits; the workspace is stood down and the record kept. Design of the process, not a record of a run.

Fig. 02Nodes carry their type, two metric rows and a state; connectors show what feeds what; dashed frames name the owners; the timeline is the cadence. Design of the pipeline, not a record of a run.

07Sources

Where the evidence comes from.

Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.

SourceWhat it givesLicence class
Software Heritage archiveArchived source code with identifiersOpen, archive terms
Zenodo and institutional repositoriesDeposited models and data with DOIsOpen, licence per record
FAIR principles for research software (FAIR4RS)Principles for reusable research softwareOpen, CC BY 4.0
CoMSES Net and model archivesArchived models with documentationOpen, licence per model
Reproducibility studies in computational scienceMeasured reproduction ratesLicence per publication
08Decisions

Who decides, and what the evidence serves.

Systems Science and Modelling prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.

Who decidesThe questionEvidence this page serves
Modelling teamsHow to package models so others can rerun themChecklists; archiving guides
Publishers and report editorsWhat reproducibility evidence to requireRerun audits
FundersWhether to fund archiving and research software engineeringReproduction rate evidence

Outputs this topic produces

  • Reproducibility checklists for models
  • Model archiving and versioning guides
  • Rerun audits of published model results
  • Open teaching material on reproducible modelling
09Core questions

What experts ask about reproducibility.

  • Is the exact model version used for a result recorded and retrievable?
  • Can the input data be traced back to their sources, with every processing step?
  • Are software environments, random seeds and hardware differences documented?
  • Can an independent team re-run the analysis without the original authors?
  • How are errors found after publication corrected and communicated?
10Mechanisms and drivers

Why modelling results fail to reproduce.

Models change constantly as code is fixed and improved. Without version control, it may be impossible to know which version produced a published result. Input data are revised, cleaned and transformed through steps that are often undocumented. Software libraries change behaviour between versions, and stochastic models depend on random seeds.

Coupled models multiply these problems, since each component has its own versions, data and settings. A result may depend on a particular combination that is never recorded.

Incentives play a role: documenting and sharing models takes time that is rarely rewarded. But irreproducible results cannot be verified, and errors in widely used models can spread into many decisions.

11Methods and data

Practices and their limits.

  1. 01

    Version control

    Recording every change to code and configuration. It requires discipline and shared conventions.

  2. 02

    Data lineage

    Documenting sources and processing steps for every input, using statistical and data stewardship practice. Some data cannot be shared.

  3. 03

    Computational environments

    Capturing software dependencies so models can be re-run. Long-term preservation remains difficult.

  4. 04

    Independent re-runs

    Having another team reproduce key results before publication. Costly but highly effective.

Reproducibility does not make a model right; it makes it checkable. Replication with independent models and data is a further step, covered in model intercomparison.

12Methods

How it is studied, and what the methods cannot say.

  1. High-performance, cloud and edge computingEnsemble design within budgets · Workflow orchestration · Reproducible environmentsApplied here
  2. Systems engineeringRequirements for decision models · Interface control for coupled modelsApplied here
  3. Probability and statisticsBayesian calibration · Proper scoring of predictions · Ensemble statisticsApplied here
13Questions

Questions and answers.

What is computational reproducibility?
The ability to obtain the same results by rerunning the same code on the same data in the same computational environment.
Why archive model code?
Because without the exact code, others cannot check how results were produced, and errors cannot be found or corrected.
What are the FAIR4RS principles?
Principles adapting FAIR to research software, so that software is findable, accessible, interoperable and reusable.
Is open-source code required?
Open code helps reproducibility but is not always possible. Where code cannot be shared, independent re-runs and detailed documentation are designed to compensate.
What is data lineage?
A record of where each input came from and every step applied to it, so that it can be traced and re-created.
Does reproducibility mean the model is correct?
No. It means the result can be checked. Correctness requires validation and comparison.
How are errors corrected?
Through dated corrections linked to the original result, reported via the platform's trust page.
Systems Science and Modelling

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