The NCEP–DOE AMIP-II Reanalysis (R-2) is an updated version of the NCEP–NCAR reanalysis (R-1), covering 1979–present. It includes improved physics, observed soil moisture forcing, and fixes several previous errors. R-2 was developed to address human processing errors in R-1 and incorporates upgrades to the forecast model and diagnostic package. It is not a next-generation reanalysis but an improved version of R-1 with corrections for human errors. R-2 provides better reanalysis results and is recommended for users affected by R-1 errors. It includes improvements in soil wetness, snow cover, radiation fluxes, and other key variables. R-2 also features a more accurate representation of cloud cover, snow budget, and land surface hydrology. However, some changes in model physics may have led to inaccuracies in certain areas, such as tropical warm pool OLR and upper-level moisture. R-2 is available for public use and is used for climate monitoring and seasonal prediction. It is also used for studies involving Southern Hemisphere case studies, near-surface temperatures, soil wetness, and snow budget analysis. R-2 is available online and is compared with R-1 in various publications. The project was supported by the NERSC and involved collaboration with the PCMDI. R-2 is considered an updated version of R-1, not a next-generation reanalysis.The NCEP–DOE AMIP-II Reanalysis (R-2) is an updated version of the NCEP–NCAR reanalysis (R-1), covering 1979–present. It includes improved physics, observed soil moisture forcing, and fixes several previous errors. R-2 was developed to address human processing errors in R-1 and incorporates upgrades to the forecast model and diagnostic package. It is not a next-generation reanalysis but an improved version of R-1 with corrections for human errors. R-2 provides better reanalysis results and is recommended for users affected by R-1 errors. It includes improvements in soil wetness, snow cover, radiation fluxes, and other key variables. R-2 also features a more accurate representation of cloud cover, snow budget, and land surface hydrology. However, some changes in model physics may have led to inaccuracies in certain areas, such as tropical warm pool OLR and upper-level moisture. R-2 is available for public use and is used for climate monitoring and seasonal prediction. It is also used for studies involving Southern Hemisphere case studies, near-surface temperatures, soil wetness, and snow budget analysis. R-2 is available online and is compared with R-1 in various publications. The project was supported by the NERSC and involved collaboration with the PCMDI. R-2 is considered an updated version of R-1, not a next-generation reanalysis.