New cluster products

Operational Upgrades

Seasonal Forecast System 4 New cluster products Migration to GRIB 2 GRIB API in 36r2 Horizontal resolution increase Unified VarEPS-Monthly Prediction System Soil Hydrology Scheme in 32r3 Seasonal Forecast System 3

Related

User guide of ECMWF products History of ECMWF model's cycle changes Full scientific and technical documentation of the IFS

Manuals

GRIB API

ECMWF has developed a new clustering application for the EPS. These products are now available operationally in dissemination, MARS and on the web. For the time being the new products will be provided in parallel to the old products. The new products are computed on a new European domain (domain=H). For type cluster means they will replace the old products and a new type cluster representative (type=CR) will be added. Type cluster standard deviations will not be produced.

The new cluster products have been added to the Catalogue of ECMWF Real-Time Products on 8.3.2011.

Current Member State users of cluster products are invited to modify their requests, see below for more details.

• Old cluster products
• New cluster products
• Technical characteristics of the new cluster products
• Actions required
• Document versions

For further information and advice regarding the upgrade, or to report any problems with the new products, please contact User Support .

Old cluster products

The old operational clustering algorithm is based on the RMS differences between the 500 hPa geopotential height ensemble forecasts, averaged from +120h to +168h taking the synoptic continuity into account. More details can be found in the Forecast User Guide.

The graphical products for the old clustering algorithm have been discontinued.

Products in GRIB code using local definition 2 are available from MARS and dissemination as follows:

For the time being the products listed in above table will be produced in parallel to the new products. .

The new cluster products will replace the old Cluster means and introduce the new type Cluster representatives.

New cluster products

The new clustering method combines a daily clustering of EPS forecasts, similar in principle to the old EPS clustering, with a set of fixed climatological regimes for each season, computed from 29 years of reanalysis data (ERA-Interim and ERA-40). Weather scenarios derived from the daily clustering and defined as the ensemble members closest to the centroid of each cluster are called cluster representative members in MARS language (type=CR). A more detailed description of the clustering method is available online.

The new graphical cluster products are available for the time windows 72-96, 120-168, 192-240 and 264-360 hours.

Products in GRIB code using local definition 32 are available from MARS and dissemination as follows:

Note that the new products, based on 500 hPa geopotential, are computed in a new domain H (30° - 75° N, 20° W - 40° E).

Further details about the dissemination requirements can be found in the Dissemination Manual.

Technical characteristics of the new cluster products

As the new products have been coded using local definition 32, they have to be handled with the following software versions:

• libemos 372 onwards
• grib_api 1.9.0 onwards

All software packages installed at ECMWF (Metview, MARS, grib_api, ...) support local definition 32.

Actions required

All Member State users retrieving the old cluster products are invited to modify their MARS and dissemination requests to comply with the requirements for the new cluster products.

All software packages installed at ECMWF (Metview, MARS, grib_api, ...) support local definition 32. However, users in Member States might have to upgrade their libemos and/or their grib_api to a version that supports this data.

Member States wishing to retrieve these products using their local MARS installation need to upgrade MARS to version 20100914.

Document versions