The objective of the NCEP’s Regional Reanalysis (RR) is to create a long-term set of consistent climate data on a regional scale, for the North American domain. The RR, or North American RR (NARR), on its domain, is/will be superior to the completed NCEP/NCAR Global Reanalysis (GR), in both resolution and accuracy. This is being achieved using the GR to drive the RR system, and taking advantage of the regional Eta Model, and of the various advances that have been made in regional modeling and data assimilation since the GR system starting time of 1995. These advances include assimilation of precipitation, direct assimilation of radiances, the use of additional data as well as improved data processing efforts, and several Eta Model developments, in particular those arrived at within the NCEP’s land-surface effort. Thus, the NARR data will be the premier North American data set for a variety of climate, NWP, predictability, water resources, and numerous other application purposes.

The resolution of the RR is 32 km/ 45 layers, and the domain used is the same as that of the operational Eta Model, covering most of North America and large parts of the adjacent oceans. The products archived consist of analysis and first guess fields, as well as free forecasts, to 72 h every 2.5 days. At the time of this writing, archival of various subsets of the RR data at three and perhaps four centers additional to NCEP is planned. The period to be covered is 25 years, 1979-2003. Once the 25 years are completed, the RR will continue to be run in real-time, like the “Climate Data Assimilation System” is being run as a real-time continuation of the GR.

As this is being submitted, the RR production is in progress on what until recently was the NCEP operational mainframe machine. Four streams are run simultaneously, of 6 years each, and various streams are more than half or close to one half done. At the end of the 6 year periods, the earlier streams will overlap and supersede the initial periods of the later streams, for minimization of the soil wetness and related spin-ups.

At the presentation, comparisons of the RR analysis as well as first guess fields against those of the GR will be presented, including temperature, wind, and relative humidity fits to radiosonde data, and 2 m temperature and 10 m wind comparisons against observations. These results are generally favorable to the RR, in particular those of the analysis fields. Also, monthly precipitation verifications will be shown, demonstrating a very high realism of the obtained RR precipitation fields. Information will also be given on a DVD to be out at the time of presentation, with a much more comprehensive set of results, including several cases of interest, some monthly means, selected twice-daily data, MOLTS, a free forecast, and additional statistics of the RR vs GR data. The monitoring tools used will be summarized, and answers to FAQ given: a list of products saved, what projections and frequency, file sizes, archiving situation and mechanisms for obtaining data as these are in place at the time of presentation. Finally, information on the RR Users Workshop to be done in early 2004 will be given.