Status of the U.S. Historical Climatology Network Monthly Data Version 2
(Additional information can be found in the readme.txt file)

10 January 2013
USHCN version 2 monthly raw and adjusted data are no longer updated.  
For the latest USHCN monthly data updates, users should use USHCN v2.5 
(which superseded v2.0 in October 2012). Data for v2.0 will continue to 
be available in static form with data provided through December 2012.  

11 April 2011
Updating of the 9641C_* files has resumed.

08 April 2011
In anticipation of the Government shutdown, updating of the 9641C_* files
has been suspended.

19 February 2010
The ./software directory has been created and the USHCN_v52d.20100217.tar.gz
and its README have been uploaded. This is the first public release of the
Pairwise Homogeniety Algorithm code, documentation for use and a benchmark case.

22 October 2009
The station list has been renamed to ushcn-v2-stations.txt to avoid
any confusion with the composition of station records in the 
version 1 ushcn data releases.

The station list has also been updated using the latest coordinates 
and station names from NCDC's MASTER_STN_HIST.TXT metadata file.  Most 
coordinates have changed only slightly; however, the longitude for 
station 214106 was incorrect by two degrees.  


07 August 2009
Raw (unadjusted) data series and series adjusted only for the Time of 
Observation bias (TOB) have been added.  See the readme.txt file for
file naming conventions and data formats. 

03 April 2009
U.S. HCN monthly data files are back on line. Some errors in the 
data flags (FLAG1, FLAG2, ...) have been corrected. 

04 February 2009
U.S. HCN data files are temporarily offline

29 January 2009
Estimates for the uncertainty associated with the adjusted mean monthly
maximum and minimum temperatures have been added (see the readme.txt 
file for the format).  Uncertainty estimates cover the period of 
record ending in 2007.

04 December 2008 
Bias adjustments for the current version of U.S. HCN monthly data have been 
determined using data for the period of record ending in
December 2007, and with version 52d of the parwise homogenization algorithm
(see Menne and Williams, 2009; J. Climate, 22, 1700-1717). 
Monthly data since 2007 are continually updated, but without any 
reevaluation of the bias adjustments.