SGP/IRT/C1 - Reprocess: Some min and max values swapped

During the time period specified the minimum and maximum sky_ir_temp
values for the first record of each hour are swapped with the minimum
being reported as sky_ir_temp_max and the maximum being reported as
sky_ir_temp_min.

• sky_ir_temp_max
• sky_ir_temp_min

SGP/IRT/C1 - Reprocess: Longwave Calibration error

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.

• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)
• Instantaneous Upwelling Longwave Hemispheric Irradiance, Pyrgeometer(inst_up_long_hemisp)

SGP/IRT/C1 - UPS failing

The IRT data were intermittently bad during this period due to a failing UPS. The problem 
was corrected by replacing the UPS.

• internal_voltage
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)
• sfc_ir_temp_std
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• Effective Surface (Skin) Temperature(sfc_ir_temp)

SGP/IRT/C1 - Contamination of 25M lens

The IRT exhibited a positive bias compared to PIR. The problem was corrected by cleaning 
the lens.

• Effective Surface (Skin) Temperature(sfc_ir_temp)
• Instantaneous Surface Infra-red Temperature(inst_sfc_ir_temp)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• sfc_ir_temp_std
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)