@article{,
title= {noaa-ncei-us-historical-climatology-network-v2-v2.5},
journal= {},
author= {Claude N. Williams and Matthew J. Menne and Peter W. Thorne},
year= {},
url= {https://www.ncei.noaa.gov/products/land-based-station/us-historical-climatology-network},
abstract= {U.S. Historical Climatology Network (USHCN) data are used to quantify national and regional-scale temperature changes in the contiguous United States (CONUS). The dataset provides adjustments for systematic, non-climatic changes that bias temperature trends of monthly temperature records of long-term COOP stations. USHCN is a designated subset of the NOAA Cooperative Observer Program (COOP) Network, with sites selected according to their spatial coverage, record length, data completeness, and historical stability. 

Version 2.5 was released as a revision to the version 2.0 dataset In October 2012. The processing steps for version 2 and 2.5 are essentially the same, but the version number change reflects modifications to the underlying database as well as coding changes to the pairwise homogenization algorithm (PHA) that improve its overall efficiency. Table 1 (below) lists these modifications. NCEI Technical Reports GHCNM-12-01R (Williams et al., 2012a) and GHCNM-12-02 (Williams et al. 2012b) provide details regarding the PHA modifications.

Version 2 monthly temperature data incorporated an expanded database of raw temperature values from COOP stations, a new set of quality control checks, and a more comprehensive homogenization algorithm. The version 2 temperature dataset and processing steps detailed description are in Menne et al. (2009).
Please see the readme file in the v2.5 directory for information on downloading and reading the v2.5 data. The status file provides information about the processing of the USHCN v2.5 data. 



Pairwise Homogeneity Algorithm (PHA) software (Menne and Williams 2009

) version 52i is used to detect and adjust for documented and undocumented inhomogeneities in the USHCN version 2.5 monthly temperature dataset.

PHA version 52d was used to adjust the v2 dataset

Please refer to the readme file in these directories for guidance on how to download, deuncompress, compile, and run the pairwise homogenization software. The "tar/g zipped" file contains all of the necessary software to run the pairwise homogenization procedure. A simulated test dataset is included with the software along with a file of the expected output. Use the file of the expected output to verify proper execution of the code.

},
keywords= {NOAA, NCEI, USHCN, CONUS, monthly temperature records, COOP, },
terms= {},
license= {},
superseded= {}
}