Cited by 213Meteorological Phenomena and SimulationsForecasting Techniques and ApplicationsClimate variability and models

Measures of skill and value of ensemble prediction systems, their interrelationship and the effect of ensemble size

Richardson, David S.·2001·Quarterly Journal of the Royal Meteorological Society

Abstract

Ensemble forecasts provide probabilistic predictions for the future state of the atmosphere. Usually the probability of a given event E is determined from the fraction of ensemble members which predict the event. Hence there is a degree of sampling error inherent in the predictions. In this paper a theoretical study is made of the effect of ensemble size on forecast performance as measured by a reliability diagram and Brier (skill) score, and on users by using a simple cost‐loss decision model. The relationship between skill and value, and a generalized skill score, dependent on the distribution of users, are discussed. The Brier skill score is reduced from its potential level for all finite‐sized ensembles. The impact is most significant for small ensembles, especially when the variance of forecast probabilities is also small. The Brier score for a set of deterministic forecasts is a measure of potential predictability, assuming the forecasts are representative selections from a reliable ensemble prediction system (EPS). There is a consistent effect of finite ensemble size on the reliability diagram. Even if the underlying distribution is perfectly reliable, sampling this using only a small number of ensemble members introduces considerable unreliability. There is a consistent over‐forecasting which appears as a clockwise tilt of the reliability diagram. It is important to be aware of the expected effect of ensemble size to avoid misinterpreting results. An ensemble of ten o…

Integrity signals

Registry

Crossref · 10.1002/qj.49712757715

Cites

9 of 9 references verified0 citation errors · 0 not checkable

Statistics

Recomputing p-values needs the paper’s full text.

Claims the paper makes

This paper’s full text isn’t openly available, so its claims and self-check weren’t run. The registry and citation checks still apply.

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • For a perfectly reliable forecast system, RPSS depends on ensemble size N according to the relationship given in the paper.

    “Generalizing the results of Richardson (2001) and Tippett et al. (2007), the RPSS of a perfectly reliable forecast system depends on ensemble size N according to (see appendix B for details):”

    From Skill of Multimodel ENSO Probability Forecasts (2008) · cites this paper as Richardson (2001)

  • Richardson (2001) showed that a reliable forecast system's Brier score depends on ensemble size N according to the given formula.

    “Richardson (2001) showed that the Brier score (BS) of a reliable forecast system depends on ensemble size N according to ͗BS͑N͒͘ ϭ ͩ 1 ϩ 1 N ͪ͗ BS͑ϱ͒͘, ͑B1͒”

    From Skill of Multimodel ENSO Probability Forecasts (2008) · cites this paper as Richardson (2001)

  • Machine learning models have significantly higher computational efficiency, facilitating the generation of a large number of ensemble members which are crucial for prediction skill and reliability.

    “Machine learning models have the advantages of significantly higher computational efficiency, facilitating the generation of a large number of ensemble members which are crucial for prediction skill and reliability24.”

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Authors
Richardson, D. S.
Affiliations
European Centre for Medium-Range Weather Forecasts (GB)
Corresponding author
Richardson, David S.
Venue
Quarterly Journal of the Royal Meteorological Society
Publisher
Wiley
Published
2001-10
Volume
127
Issue
577
Pages
2473-2489
ISSN
  • 0035-9009 (ISSN-L)
  • 1477-870X
OpenAlex
W2089463042
Cited by
212
References
9
Citations by year
2026: 8 · 2025: 9 · 2024: 10 · 2023: 8 · 2022: 11 · 2021: 7 · 2020: 6 · 2019: 13 · 2018: 14 · 2017: 6 · 2016: 8 · 2015: 8 · 2014: 12 · 2013: 7 · 2012: 6
FWCI
3.05
Type
journal article
Language
en
Open access
closed
Locations
Quarterly Journal of the Royal Meteorological Society (publishedVersion)
Topics
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Meteorological Phenomena and Simulations
  • Social Sciences › Decision Sciences › Management Science and Operations Research › Forecasting Techniques and Applications
  • Physical Sciences › Environmental Science › Global and Planetary Change › Climate variability and models
Keywords
ensemble prediction systems, ensemble size, Brier skill score, reliability diagrams, forecast reliability, sampling error, forecast value, probabilistic forecasting, predictability, extreme events, user sensitivity

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review