Data processing and forecasting systems meeting of the joint expert teams on long-range forecasting

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Basic properties

Temporal resolution.

Monthly averages/accumulations for a season
Spatial resolution.

2.5 x 2.5 (note: selected to match resolution of current verification data)
Spatial coverage. Global

(separate areas of interest to users, down to sub-regions of a continent or ocean basin, may be provided on special request from Members)

Lead time. 0-4 months for seasonal forecasts. Note on definition of lead time: for example, a three-monthly forecast issued on 31 December has a lead time of 0 months for a January-to-March forecast, and a lead time of 1 month for February-to-April forecast, etc.
Issue frequency. Monthly and/or quarterly
Output types. Gridded numerical values, area-averaged values and indices, and/or images. GRIB-2 should be used for products posted on FTP-sites or disseminated through the GTS or the Internet
Indications of skill including hindcast must be provided, in accordance with recommendations from CBS on the Standardised Verification System( attachment II-8). The minimum required is level 1 and level 2 verification. The verification of Nino3.4 index will only apply to those centres producing such indices. However GPCs are encouraged to provide level 3 verification. Verification results over the hindcast period are mandatory.

Content of basic forecast output: (some products are intended as directly meeting NMS requirements with regard to information needed for end-user applications [direct or further processed]; others are to assist the contributing global centres in product comparison and in the development of multimodel ensembles. These products are regarded as feasible from current systems).

  1. Calibrated outputs from ensemble prediction system showing the mean and spread of the distribution for:


1. These fields are to be expressed as departures from normal model climate.

2. SST used as boundary conditions for (two-tiered) AGCM predictions should be made available.

  1. Calibrated probability information for forecast categories. Tercile categories should be provided, consistent with present capabilities. Information for larger numbers of categories (e.g. deciles) is foreseen, however, as capabilities increase and to match better the anticipated end-user requirements. These targets are implied also for forecasts from statistical/empirical models.

Note: information on category boundaries should be included.

  • 2 metre temperature over land

  • SST (Atmospheric coupled models only)

  • Precipitation

(Note: "Calibrated" implies correction based on systematic errors in model climatology, using at least 15 years of retrospective forecasts.)

Annex to paragraph 4.3

  1. Lead Centre role

WMC Melbourne (Australian Bureau of Meteorology - BoM, Australia) and RSMC Montreal (Canadian Meteorological Centre – CMC) have been nominated co-lead centres for the development and maintenance of the Web Site for exchange of SVSLRF verification results. It is recognized that the role of the Lead Centre is to facilitate the availability of information to assess the skill of long-range forecasts but not to provide a direct inter-comparison between the GPCs’ models. The role of the Lead Centre is mainly:



To develop and maintain the SVSLRF web site.

WMC Melbourne and RSMC Montreal

To host the SVSRLF web site.

WMC Melbourne

To develop the structure of the SVSLRF web site (HTML code, etc.).

WMC Melbourne

To provide access to verification datasets on the SVSLRF web site.

RSMC Montreal

To update the verification datasets on the SVSLRF web site on a yearly basis provided that new data is made available.

RSMC Montreal

To develop and provide specifications defining the format of the data to be sent to the Lead Centre for graphics preparation. The infrastructure to generate all graphics posted on the SVSLRF web site will have to be developed.

WMC Melbourne

To make available on the web site the digital verification information as specified at levels 1, 2 and 3 in Attachment II.9 of the Manual on GDPS. This implies that a structured database will be developed to store digital verification results.

WMC Melbourne

To ensure that clear and concise documentation explaining the verification scores, graphics and data is available and maintained up-to-date on the SVSLRF web site.

RSMC Montreal and WMC Melbourne

To consult with the GPCs to make sure that the verification data is correctly displayed before making available their verification results on the SVSLRF web site.

WMC Melbourne and RSMC Montreal

To ensure that the verification results placed on the SVSLRF web site comes from officially recognized global producing centres with operational guidance commitments.

WMC Melbourne and RSMC Montreal

To provide and maintain software to calculate the verification scores (ROC curves, ROC score, MSSS, contingency table scores, hit rates…)..

RSMC Montreal

To ensure that appropriate hypertext links to participating GPCs are available on the SVSLRF web site.

WMC Melbourne and RSMC Montreal

To publicise the SVSLRF web site to other organizations involved in verification (such as WGSIP, COLA etc.) and establish contacts in order to receive feedback and facilitate discussion for further development and improvement.

WMC Melbourne and RSMC Montreal

Once the SVSLRF web site is operational, to provide progress reports every two years to CBS, prior to its meetings.

WMC Melbourne and RSMC Montreal

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