NSA/SKYRAD/C1 - itermittant IRT bias

A problem with the SKYRAD IRT that itermittantly produced a gradual increase in the sky 
temperature measurement then a sudden correction, as compared to AERI, appears to have been 
caused by a combination of a failing IR detector, a poor signal cable, a contaminated 
(with condensation or frost) mirror or lens, and low ambient temperatures. The positive 
bias was apparently not consistant in either frequency or duration but on days when the 
unusual behavior is observed, it usually occurred from about 00:00 to 06:00 local time. 

The instrument was repaired and recalibrated and the signal cable replaced.

• Sky Infra Red Temperature Minima(sky_ir_temp_min)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)
• Sky Infra-Red Temperature(sky_ir_temp)

NSA/SKYRAD/C1 - IRT failure

The IRT failed and was replaced with a spare.

• Sky Infra Red Temperature Minima(sky_ir_temp_min)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)
• Sky Infra-Red Temperature(sky_ir_temp)

NSA/SKYRAD/C1 - Power outage affecting some SKYRAD instruments

During the power outage the downwelling global measurement from the PSP instrument and 
downwelling diffuse 8-48 instrument shows a slight increase from -5 to +0 W/m2.  This is due 
to removal of thermal offsets induced by the AC heater during the power outage.  This 
heater is installed within the PSP ventilator - it is necessary for the NSA/C1 climate.
The downwelling longwave PIR instrument is unaffected due to case and dome temperature 
corrections.
The IRT is AC powered and was not operational during this time period.

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)

• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Down-welling unshaded pyranometer voltage(down_short_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Standard
  Deviation(down_short_hemisp_std)
• Sky Infra-Red Temperature(sky_ir_temp)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Standard Deviation(down_short_diffuse_hemisp_std)

• Instantaneous Downwelling Hemispheric Shortwave, Unshaded Pyranometer Thermopile
  Voltage(inst_global)
• Instantaneous Sky/Cloud Infrared(inst_sky_ir_signal)
• Instantaneous Uncorrected Downwelling Shortwave Diffuse, Shaded Pyranometer
  Thermopile Voltage(inst_diffuse)

NSA/SKYRAD/C1 - Instrument noise

Skyrad data appears affected by noise creating bias in analog voltage readings on 
02/15/2006 from 1300-1800GMT and again on 02/16/2006 from 1300-1500GMT.  The second night the 
noise is attenuated significantly.  By 02/17 no bias/noise is detectable. The thermistor 
measurements in PIR1 and PIR2 were unaffected during these excursions and showed no 
deviation from normal during the problem period.  In addition, the onboard logger temperature and 
battery voltage read normal throughout.  The problem has not reappeared as of 4/25/2006.

• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Down-welling unshaded pyranometer voltage(down_short_hemisp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Minima(down_long_hemisp_shaded1_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2, Minima(down_long_hemisp_shaded2_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp_shaded1)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Standard
  Deviation(down_short_hemisp_std)
• Sky Infra-Red Temperature(sky_ir_temp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp_shaded2)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Minima(short_direct_normal_min)
• Sky Infra Red Temperature Minima(sky_ir_temp_min)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Maxima(short_direct_normal_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Maxima(down_long_hemisp_shaded1_max)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2, Maxima(down_long_hemisp_shaded2_max)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)
• Shortwave Direct Normal Irradiance, Pyrgeometer(short_direct_normal)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Standard
  Deviation(down_long_hemisp_shaded1_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2, Standard
  Deviation(down_long_hemisp_shaded2_std)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Standard Deviation(down_short_diffuse_hemisp_std)

• Instantaneous Downwelling Pyrgeometer Thermopile, Shaded Pyrgeometer2(inst_down_long_hemisp_shaded2_tp)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Shaded
  Pyrgeometer1(inst_down_long_shaded1_dome_resist)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Shaded
  Pyrgeometer2(inst_down_long_shaded2_dome_resist)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Shaded
  Pyrgeometer1(inst_down_long_shaded1_case_resist)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Shaded
  Pyrgeometer2(inst_down_long_shaded2_case_resist)
• Instantaneous Sky/Cloud Infrared(inst_sky_ir_signal)
• Instantaneous Downwelling Pyrgeometer Thermopile, Shaded Pyrgeometer1(inst_down_long_hemisp_shaded1_tp)
• Instantaneous Downwelling Hemispheric Shortwave, Unshaded Pyranometer Thermopile
  Voltage(inst_global)
• Instantaneous Direct Normal Shortwave Irradiance, Pyheliometer Thermopile
  Voltage(inst_direct_normal)
• Instantaneous Uncorrected Downwelling Shortwave Diffuse, Shaded Pyranometer
  Thermopile Voltage(inst_diffuse)

NSA/SKYRAD/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.

• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp_shaded1)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp_shaded2)