Student or educator? Sign up with your school email and get 6 months of Pro free.
Cited by 668

The DOI matches its Crossref record; 31 of the 31 references it cites were found in a registry or an index.

The ECMWF implementation of three‐dimensional variational assimilation (3D‐Var). I: Formulation

Courtier, P., Andersson, E., Heckley, W., Vasiljevic, D., Hamrud, M., Hollingsworth, A., Rabier, F., Fisher, M., Pailleux, J.·1998·Quarterly Journal of the Royal Meteorological Society

Abstract

In the first of this set of three papers, the formulation of the European Centre for Medium‐Range Weather Forecasts (ECMWF) implementation of 3D‐Var is described. In the second, the specification of the structure function is presented, and the last is devoted to the results of the extensive numerical experimentation programme which was conducted. The 3D‐Var formulation uses a spherical‐harmonic expansion, much as the ECMWF optimal interpolation (OI) scheme used an expansion of Bessel functions. This formulation is introduced using a convolution algebra over the sphere expressed directly in spectral space. It is shown that all features of the OI statistical model can be implemented within 3D‐Var. Furthermore, a non‐separable statistical model is described. In the present formulation, geostrophy is accounted for through a Hough‐modes separation of the gravity and Rossby components of the analysis increments. As in OI, the tropical analysis remains essentially non‐divergent and with a weak mass‐wind coupling. The observations used, as well as their specified statistics of errors, are presented, together with some implementation details. In the light of the results, 3D‐Var was implemented operationally at the end of January 1996.

Overview

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1002/qj.49712455002

Cites

31 of 31 references verified0 citation errors · 0 not checkable

Statistics

Verification

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Citations

Cites

Show all 31 references

Cited by

See all 668

Metadata

Authors
Courtier, P., Andersson, E., Heckley, W., Vasiljevic, D., Hamrud, M., Hollingsworth, A., Rabier, F., Fisher, M., & Pailleux, J.
Venue
Quarterly Journal of the Royal Meteorological Society
Publisher
Wiley
Published
1998-07
Volume
124
Issue
550
Pages
1783-1807
ISSN
  • 0035-9009 (ISSN-L)
  • 1477-870X
OpenAlex
W2104355414
Cited by
668
References
31
FWCI
18.48
Type
journal article
Language
en
Open access
closed

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

How to cite

Cite CoChat for the checks on this page, and the paper for its own findings.

This page
CoChat. (2026). Citation check: The ECMWF implementation of three‐dimensional variational assimilation (3D‐Var). I: Formulation. https://app.cochat.ai/papers/10.1002/qj.49712455002
The paper
Courtier, P., Andersson, E., Heckley, W., Vasiljevic, D., Hamrud, M., Hollingsworth, A., Rabier, F., Fisher, M., & Pailleux, J. (1998). The ECMWF implementation of three‐dimensional variational assimilation (3D‐Var). I: Formulation. Quarterly Journal of the Royal Meteorological Society. https://doi.org/10.1002/qj.49712455002

Data sources

Bibliographic data: Semantic Scholar, OpenAlex, Crossref.

Contains information from the Semantic Scholar Academic Graph Datasets, made available under the ODC Attribution License (ODC-BY 1.0).

Semantic Scholar’s data is described in: Kinney, R., et al. (2023). The Semantic Scholar Open Data Platform. arXiv:2301.10140.