SGP/BRS/C1 - Reprocess: Incorrect Calibration Coefficients

Lightening strike on or near 6/2/2004 took the BRS NIP(31747E6) out of service, on or near 
6/15 the NIP was replaced and the datalogger program was changed to reflect the new 
NIP(31343E6). On 8/5/2004 the DIR (Downwelling longwave) instrument was changed out and a new 
program was loaded to reflect a new DIR.  The new program contained the original 
installed shortwave instrument calibration coefficients including NIP 31747E6. Thus from 8/5 to 
when the shortwave instruments were changed out on 12/3 the wrong s/n and calibration 
factor (i.e. 31747E6) was applied to the actual NIP(31343E6)installed at BRS C1.

• Shortwave Direct Normal Irradiance, Pyrgeometer(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Maxima(short_direct_normal_max)

• Instantaneous Direct Normal Shortwave Irradiance, Pyheliometer Thermopile
  Voltage(inst_direct_normal)

• null(Raw data stream - documentation not supported)

SGP/BRS/C1 - low downwelling shortwave readings

Downwelling shortwave (DS) values frequently drop below -10 W/m^2 at night, and are 
consistently 20-40 W/m^2 less than the calculated downwelling shortwave during the day in 
clear-sky conditions. Corrective maintenance on 12/17/2004 corrected this offset.  It is not 
clear which CM action corrected the problem since the DS instrument cable was grounded to 
a new location and the DS ventilator fan was found in poor condition and was replaced.  
Either of these issues could have led to the problem observed in this instrument.

• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Standard
  Deviation(down_short_hemisp_std)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Down-welling unshaded pyranometer voltage(down_short_hemisp)

• Instantaneous Downwelling Hemispheric Shortwave, Unshaded Pyranometer Thermopile
  Voltage(inst_global)

• null(Raw data stream - documentation not supported)

SGP/BRS/C1 - Reprocessed: Longwave Calibration error

Modified pyrgeometer calibration procedures were implemented beginning in June 2004. 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 have been reprocessed to 
remove the calibration bias.  The reprocessed 60 second averaged data are based on 3 
instantaneous 20 second data records rather than on 60 1 second instantaneous data records. 
Still, these data are considered far superior to the originally processed data. The 
reprocessed data were archived in November 2006.

• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer(down_long_hemisp_shaded)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Pyrgeometer(up_long_hemisp)
• Upwelling Longwave Hemispheric Net Infrared(up_long_netir)
• Downwelling Longwave Hemispheric Net Infrared(down_long_netir)