National Temperature Index
In early 2014, the National Oceanic and Atmospheric Administration's (NOAA's) National Centers for Environmental Information (NCEI, known then as the National Climatic Data Center) began using a divisional data set based on 5 km resolution gridded temperature data. The new divisional data set, nClimDiv, differs from USHCN in several ways. In particular, nClimDiv makes use of a much larger set of stations (over 10,000) and includes observations from many networks not included in USHCN (e.g., RAWS and SNOTEL). nClimDiv also uses a different computational approach known as climatologically aided interpolation, which helps address topographic variability and changes in the station network through time. As a result, NCEI began using nClimDiv data to compute contiguous (CONUS) temperatures, replacing USHCN as the official CONUS temperature data set. Notably, both datasets use the same bias adjustment approach for addressing historical changes in station location, temperature instrumentation, observing practice, and siting conditions.