Summary

Description

The North America Regional Reanalysis (NARR) Project is a reanalysis of historical observations using a 32-km version of the National Centers for Environmental Prediction (NCEP) 1993 operational ETA model and ETA data assimilation system (EDAS). The objective is to create a long-term set of consistent climate data on a regional scale for the North American domain. The domain of analyses includes North and Central America as well as small parts of the United Kingdom, Eastern Asia, South America, and areas of the Pacific and Atlantic Oceans. The period of the reanalyses is from October 1978 to the present and analyses were made 8 times daily (3 hour intervals). Horizontal boundary conditions are derived from the NCEP/DOE Global Reanalysis. Advantages over the widely used NCEP/NCAR Reanalysis (180 km) are its higher spatial and temporal resolutions (32 km grid, 45 vertical layers, every three hours) and better treatment of the land surface. This is achieved through the use of a better land-surface model (Noah LSM), the assimilation of more observational data (precipitation, upper air and surface winds), and through a better representation of the terrain (heights, vegetation, soil type). This data set contains "conventional" atmospheric analyses as well as model-derived fields that contain estimates of subsurface, surface, and radiative properties. This data set is encoded in WMO GRIB format version 1 using the NCEP GRIB table 131. The model used a native, "E-grid" for its calculations, however data were interpolated to a Lambert Conformal Conic projection, also known as NAM 221 AWIPS Grid - High Resolution North American Master Grid (32-km Resolution). All vector components are earth relative rather than grids relative which is the convention for operational NCEP model. The list of fields produced by the NARR ETA model differ from the operational ETA model. NARR data files that are compatible with the Grid Analysis and Display System (GrADS) are available.