February 14, 2013

An omission in the USHCN Time of Observation bias (TOB) correction process 
prevented the seasonally varying TOB adjustments from being applied 
to the USHCN version 2.5 "FLs.52i" temperature data.  This ommission
began on Oct. 22, 2012.  The ommission was rectified on February 12, 2013 
when the seasonally varying TOB adjustment resumed in the processing o
f the FLs.52i files.

Between October 22, 2012 and February 12, 2013, the Pairwise Homogeneization 
Algorithm (PHA) continued to function and provided an annual mean 
correction for the time of observation bias in the processing of 
the "FLs.52i" files. 

Additional details on may be found at 
http://www.ncdc.noaa.gov/sotc/national/2013/1/supplemental/page-5 


04 October 2012
USHCN v2.5 data are expected to be deployed to this ftp directory
during the week of October 8, 2012