TIGGE, the THORPEX Interactive Grand Global Ensemble, is a key component of the World Weather Research Programme intended to accelerate improvements in 1-day to 2-week weather forecasts. Centralized archives of ensemble model forecast data, from many international centers, will be used to enable extensive data sharing and research. The designated TIGGE archive centers include the Chinese Meteorological Administration (CMA), The European Center for Medium-Range Weather Forecasts (ECMWF), and The National Center for Atmospheric Research (NCAR). Scientific data requirements and archive planning solidified in late 2005, and archive collection was initiated in September 2006. This paper will review the status and plans for TIGGE at NCAR and ECMWF.

The Unidata Internet Data Distribution (IDD) system is used to transport the ensemble model data from the providers to the archive centers. Currently, the output from the ECMWF and UK Met Office (UKMO) global models, totaling 130 GB/day, is moved at 10 GB/hour from ECMWF to NCAR. When other international centers (from Australia, Brazil, Canada, China, Korea, Japan, France and the US) join the TIGGE data effort, the flow is expected to top 200 GB/day and be well within the capacity for the IDD. By requirement the parameter fields, atmospheric levels, and physical units are consistent across all data from the providers and encoded in WMO GRIB-2 format (http://tigge.ecmwf.int). In contrast, each provider may submit their model output in a resolution they choose.

TIGGE data are available to the public for non-commercial research, with a 48-hour delay after forecast initialization time. At NCAR, users can discover data through the TIGGE portal (http://tigge.ucar.edu) and directly download complete forecast files for the most current two-week period. Forecast files are organized by level type (single level, pressure level, potential vorticity level, and potential temperature level), and forecast time-step for a specified model. All ensemble members are included in each forecast file. At ECMWF, users can discover and download data through a web interface linked to the Meteorological Archival and Retrieval System (MARS) (http://tigge.ecmwf.int). Each center will offer fast access to terabytes of data kept online and delayed access to the long term archives preserved in their archive systems. Planned future additions to the TIGGE portals include user specified sub-setting and uniform interpolation across multiple center output, and web services that will give users a common interface to request data at all archive centers.