Global And Regional Scales

So far several different reanalysis projects have been carried out both at the global and regional scales by organizations in the United States, Japan, and Europe, including the National Center for Environmental Prediction (NCEP), National Center for Atmospheric Research (NCAR), United States Department of Energy (DoE), Japan Meteorological Agency (JMA) and the European Centre for Medium-Range Weather Forecasts (ECMWF).

The NCEP and NCAR commenced a joint project, in 1991, to produce a global reanalysis dataset over the period 1957-96 which is continuing beyond the initial period. The model has a T62 (about 130 mi. or 210 km.) horizontal resolution with 28 vertical levels; the data are provided at the 6-hour, daily, and monthly scales. This reanalysis product is often called NCEP/ NCAR Reanalysis 1. Reanalysis 1 has been widely used in climate modeling communities to provide boundary conditions for general circulation models.

The NCEP/DoE AMIP-II Reanalysis (Reanalysis 2) is an updated version, but not the next generation of Reanalysis 1. Based on Reanalysis 1, Reanalysis 2 was developed by improving parameterization of physical processes and fixing errors in Reanalysis 1, with data coverage since 1979.

Japanese 25-year ReAnalysis (JRA-25) was created by JMA in collaboration with Central Research Institute of the Electric Power Industry for the period 1979-2004 and was transitioned to Japanese Reanalysis Project-Categorical Data Analysis System (JMA-CDAS) after 2005.

The global model has a T106 (about 68 mi. or 110 km.) horizontal resolution with 40 vertical layers. It is the first reanalysis project to use wind profile retriev als surrounding tropical cyclones (TCR), Special Sensor Microwave/Imager (SSM/I) snow coverage and digitized Chinese snow depth data.

The European Centre for Medium-Range Weather Forecasts (ECMWF) developed the ERA 15 Re-Analysis project in association with various organizations around the world. ERA 15 Re-Analysis incorporated various observational data including NOAA satellite radiance data for the 15-year period, the Comprehensive Ocean-Atmosphere Data Set (COADS) ship data, the First GARP Global Experiment (FGGE) and the Alpine Experiment (ALPEX) data, and pseudo-observational data from the Australian Bureau of Meteorology. The dataset spans from January 1979 through February 1994 and is available on a 2.5 degrees latitude x 2.5 degrees longitude grid.

North American Regional Reanalysis (NARR) is "a long-term, consistent, high-resolution climate dataset for the North American domain" with major improvements in both resolution and accuracy compared to previous global reanalysis datasets. It has a spatial resolution of 20 sq. mi. (32 sq. km.), a vertical resolution of 45 layers and a temporal resolution of 3 hours from 1979 to the present. It uses the NCEP Eta forecast model with lateral boundary conditions provided by the NCEP-DoE Reanalysis 2 and the Eta model Data Assimilation System. Data added or improved upon for NARR include precipitation measured over the United States, Mexico and Canada, wind and moisture from Reanalysis 2, pressure, wind, moisture from NCAR, ship and buoy data from NCEP/EMC (Environmental Modeling Center), snow depth from Air Force Weather Agency, Great Lakes sea-surface temperature, sea and lake ice data on Canadian lakes and Great Lakes, and tropical cyclones from Lawrence Livermore National Laboratory. The most striking feature of NARR is the successful assimilation of precipitation observations, which lead to the more realistic hydrological cycle.

SEE ALSO: Climate Models; Climatic Data, Cave Records; Climatic Data, Ice Observations; Climatic Data, Lake Records; Climatic Data, Sea Floor Records; Climatic Data, Sediment Records; Climatic Data, Tree Ring Records.

BIBLIOGRApHY. American Meteorological Society (AMS), Glossary of Meteorology 2nd ed. (AMS, 2000); Lennart Bengtsson, Michael Ghil, and Erland Kallen (eds.), Dynamic

Meteorology: Data Assimilation Methods (Springer-Verlag, 1981); Eugenia Kalnay, Atmospheric Modeling, Data Assimilation, and Predictability (Cambridge University Press, 2003); Eugenia Kalnay et al., Bulletin of the American Meteorological Society (AMS, 1996); Masao Kanamitsu et al. Bulletin of the American Meteorological Society (AMS, 20023), Fedor Messinger et al., Bulletin of the American Meteorological Society (AMS, 2006).

Woonsup Choi University of Manitoba

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