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

SGP/IRT/C1 - Measurement range

The ground surface temperature exceeded the maximum measurement of 50C on some days. The 
maximum was increased to 60C for IRT10m on 10/1/2012 at 15:25 and for IRT25m on 10/9/2012 
at 21:45.

• Effective Surface (Skin) Temperature(sfc_ir_temp)
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)

• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)
• Effective Surface (Skin) Temperature(sfc_ir_temp)

SGP/IRT/C1 - 25m IRT ground surface temperature

The 10m IRT was measuring lower ground surface temperature than the 25m IRT. The 25m lens 
was cleaned on 12/24/2012 and replaced on 2/8/2013 but the difference in temperature 
appears to be due to the seasonal difference in surface cover - tall grass vesus bare soil.

• Effective Surface (Skin) Temperature(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)

SGP/IRT/C1 - Degraded hardware

The surface temperature from the 25m IRT was ~10K less than measured from the PIR. The 
lens was replaced on 2/8/2013 but there is still a bias. The problem was corrected when the 
IRT (and that at 10m) was upgraded to a newer model.

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