Modified pyrgeometer calibration procedures were implemented beginning in December 2003.
These modified procedures introduced a calibration bias in the longwave data. The
previous procedures were re-implemented at all sites between December 2005 and February 2006 to
restore proper calibrations.
The data collected while the incorrect procedures were in place are
being reprocessing to remove the calibration bias. Note, this also affected standard
deviation, maximum and minimum data fields.