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_ir_temp_min
• sky_ir_temp_std
• sky_ir_temp_max
• Temperature, Sky Infra-Red(sky_ir_temp)

NSA/SKYRAD/C1 - IRT failure

The IRT failed and was replaced with a spare.

• sky_ir_temp_min
• sky_ir_temp_std
• sky_ir_temp_max
• Temperature, Sky Infra-Red(sky_ir_temp)

NSA/GNDRAD/C1 - power outage affecting some GNDRAD sensors

During the power outage the upwelling global measurement from the PSP 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 upwelling 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.

• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Maxima(up_short_hemisp_max)
• up_short_hemisp_std
• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Minima(up_short_hemisp_min)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• sfc_ir_temp_std
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)
• Effective Surface (Skin) Temperature(sfc_ir_temp)
• Radiation, shortwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_short_hemisp)

• Raw data stream - documentation not supported

• inst_sfc_ir_signal

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

• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_diffuse_hemisp_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• down_short_hemisp_std
• Temperature, Sky Infra-Red(sky_ir_temp)

• inst_global
• inst_diffuse
• inst_sky_ir_signal

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.

• down_long_hemisp_shaded2_std
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• sky_ir_temp_min
• sky_ir_temp_max
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• down_long_hemisp_shaded2_max
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• down_long_hemisp_shaded1_max
• down_short_hemisp_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• short_direct_normal_std
• Temperature, Sky Infra-Red(sky_ir_temp)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• down_long_hemisp_shaded2_min
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_diffuse_hemisp_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• sky_ir_temp_std
• down_long_hemisp_shaded1_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• down_long_hemisp_shaded1_min

• inst_down_long_shaded1_case_resist
• inst_down_long_shaded1_dome_resist
• inst_sky_ir_signal
• inst_direct_normal
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• inst_global
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded2_dome_resist
• inst_down_long_shaded2_case_resist
• inst_diffuse

NSA/SKYRAD/C1 - Summer solstice shading of radiometers

On and around the summer solstice, the NIP (Direct Normal shortwave measurement) and PSP 
(global hemispheic shortwave measurement) radiometers are shaded by other instruments or 
support structures.  Shading azimuths have been determined for this site.  The radiometer 
mentor suggests not using the data from the NIP and PSP radiometers when the sun is 
within the following azimuth bounds (typically from May 8th to August 5th of each year):
Instrmt Obstruction     AzStart     AzEnd     
NIP     rad table       346         358
NIP     met tower       13          15
PSP     mfrsr           6           16

• psps_sd
• psp1_sd
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• psps_mean
• psps_min
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• nip_sd
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• psp1_min
• psp1_max
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• nip_mean
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• nip_min
• psps_max
• nip_max
• psp1_mean
• down_short_hemisp_std
• short_direct_normal_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)

NSA/GNDRAD/C1 - Incorrect calibration coefficients

BarrowC1, Gndrad. On Aug 11th the PSP-US was changed out and the Campbell program was 
changed to reflect this.  However, an old program that uses the 4 coefficient PIR cal factors 
was used. The PIR-UIR was not changed out, however, the logger program coeffs reverted 
back to the 4 Coeffcients.  The Eppley PIR-UIR coefficients for this S/N 30168F3 are :  
K0=0.0, K1(aka k)=.25253, K2= 1.0, K3=-4, Kr=0.0.

• net_min
• pir1_mean
• net_std
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Maxima(up_long_hemisp_max)
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Minima(up_long_hemisp_min)
• pir1_sd
• net_mean
• net_sd
• up_long_hemisp_std
• net_max
• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)
• pir1_max
• pir1_min

• Raw data stream - documentation not supported

• pir1_case_therm
• inst_up_long_hemisp_tp
• inst_up_long_case_resist
• pir1_dome_therm
• pir1_voltage
• inst_up_long_dome_resist

• inst_up_long_dome_resist
• inst_up_long_hemisp_tp
• inst_up_long_case_resist