NSA/SKYRAD/C2  - Solar tracker problem.

Beginning on 6/13, there was a problem with the solar 
tracker/shading at Atqasuk.  The observed downwelling shortwave
was not in good agreement with the theoretical value calculated 
from the direct, diffuse, and solar zenith angle, which usually 
indicates a tracking problem. The direct (NIP) data occasionally 
exhibited a stair-step pattern of dropping off slightly for a few 
minutes, then rising, then dropping off again, rather than the 
smooth increase during the hours of greater sunlight that is 
normally observed in clear sky conditions.

This problem was resolved on the morning of 6/20.

• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(down_short_diffuse_hemisp_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Standard Deviation(short_direct_normal_std)

NSA/SKYRAD/C1 - IRT incorrect min/max value

The values of valid_min and valid_max for field sky_ir_temp were incorrectly assigned to 
-49.7 and +50.0 C, respectively. The actual values should be -60 and +40 C.

• Sky/Cloud Infra-Red Temperature Minima(sky_ir_temp_min)
• Sky/Cloud Infra-Red Temperature Maxima(sky_ir_temp_max)
• Sky/Cloud Infra-Red Temperature(sky_ir_temp)

NSA/SKYRAD/C2  - IRT incorrect min/max values

The values of valid_min and valid_max for field sky_ir_temp were incorrectly assigned to 
-49.7 and +50.0 C, respectively. The actual values should be -60 and +40 C.

• Sky/Cloud Infra-Red Temperature Maxima(sky_ir_temp_max)
• Sky/Cloud Infra-Red Temperature Minima(sky_ir_temp_min)
• Sky/Cloud Infra-Red Temperature(sky_ir_temp)

NSA/SKYRAD/C1 - Missing data due to Logger Failure

Logger failure resulted in missing data during the specified period.

• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Unshaded
  Pyrgeometer(inst_down_long_unshaded_case_resist)
• east longitude for all the input platforms.(lon)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Shaded
  Pyrgeometer(inst_down_long_shaded_case_resist)
• Instantaneous Downwelling Pyrgeometer Thermopile Voltage, Shaded Pyrgeometer(inst_down_long_hemisp_shaded_tp)
• north latitude for all the input platforms.(lat)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Shaded
  Pyrgeometer(inst_down_long_shaded_dome_resist)
• altitude above sea levelaltunits(alt)
• Instantaneous Downwelling Ultraviolet Biometer Temperature(inst_down_uvb_temp)
• Instantaneous PIR2 case thermistor(pir2_case_therm)
• Instantaneous Uncorrected Downwelling Ultraviolet Irradiance, UV Biometer(inst_down_uvb_irradiance)
• Instantaneous Downwelling Pyrgeometer Thermopile, Unshaded Pyrgeometer(inst_down_long_hemisp_unshaded_tp)
• Instantaneous PIR2 dome thermistor(pir2_dome_therm)
• Time offset of tweaks from base_time(time_offset)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Unshaded
  Pyrgeometer(inst_down_long_unshaded_dome_resist)
• GPS raw data filename(filename)
• Instantaneous PIR1 case thermistor(pir1_case_therm)
• Instantaneous UVB temperature(uvb_temp)
• Instantaneous UVB uncorrected irradiance(uvb_uncorr_irradiance)
• Instantaneous PIR2 uncorrected irradiance(pir2_uncorr_irradiance)
• Instantaneous PIR1 uncorrected irradiance(pir1_uncorr_irradiance)
• Instantaneous PIR1 dome thermistor(pir1_dome_therm)
• Time offset from base_time(base_time)

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

• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer(down_short_hemisp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer(down_long_hemisp_shaded)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_shaded_std)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• Sky/Cloud Infra-Red Temperature(sky_ir_temp)
• IRT1 minimum(irt1_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Maxima(down_long_hemisp_shaded1_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_unshaded_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Bit data. See details.(bit_data)
• PSP1 unshaded mean(psp1_mean)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(down_short_diffuse_hemisp_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Minima(down_long_hemisp_shaded1_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Maxima(down_long_hemisp_unshaded_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2, Minima(down_long_hemisp_shaded2_min)
• GPS raw data filename(filename)
• PSP1 unshaded minimum(psp1_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Time offset from base_time(base_time)
• PIR1 unshaded minimum(pir1_min)
• UVB minimum(uvb_min)
• PIR shaded minimum(pirs_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Sky/Cloud Infra-Red Temperature Maxima(sky_ir_temp_max)
• PIR1 unshaded standard deviation(pir1_sd)
• Internal voltage(internal_voltage)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2, Maxima(down_long_hemisp_shaded2_max)
• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)
• IRT1 maximum(irt1_max)
• Internal Logger Temperature(logger_temp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Standard
  Deviation(down_long_hemisp_shaded1_std)
• east longitude for all the input platforms.(lon)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Maxima(down_short_hemisp_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp_shaded1)
• NIP maximum(nip_max)
• PIR shaded maximum(pirs_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Standard
  Deviation(down_short_hemisp_std)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp_shaded2)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• PSP shaded minimum(psps_min)
• PSP1 unshaded standard deviation(psp1_sd)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Standard Deviation(short_direct_normal_std)
• UVB mean(uvb_mean)
• Time offset of tweaks from base_time(time_offset)
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• NIP minimum(nip_min)
• Sky/Cloud Infra-Red Temperature Standard Deviation(sky_ir_temp_std)
• Shortwave Direct Normal Irradiance, Pyrheliometer(short_direct_normal)
• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)
• UVB standard deviation(uvb_sd)
• north latitude for all the input platforms.(lat)
• PIR shaded standard deviation(pirs_sd)
• PIR shaded mean(pirs_mean)
• NIP standard deviation(nip_sd)
• NIP mean(nip_mean)
• Downwelling Ultra-Violet Irradiance, UV Biometer, Standard Deviation(down_uvb_std)
• PSP shaded mean(psps_mean)
• Sky/Cloud Infra-Red Temperature Minima(sky_ir_temp_min)
• UVB maximum(uvb_max)
• PIR1 unshaded mean(pir1_mean)
• PSP shaded standard deviation(psps_sd)
• altitude above sea levelaltunits(alt)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer(down_long_hemisp_unshaded)
• IRT1 standard deviation(irt1_sd)
• PIR1 unshaded maximum(pir1_max)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Minima(down_long_hemisp_unshaded_min)
• External voltage(external_voltage)
• PSP shaded maximum(psps_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Minima(down_short_hemisp_min)
• PSP1 unshaded maximum(psp1_max)
• IRT1 mean(irt1_mean)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2, Standard
  Deviation(down_long_hemisp_shaded2_std)

NSA/SKYRAD/C2 - IRT measurements during precipitation events

The IRT measurement of sky/cloud temperature was in question during
precipitation events because rain or snow could accumulate in the 
upward-pointed lens barrel. This was corrected by reorienting the
IRT to measure the sky temperature as reflected by a gold mirror.

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

NSA/SKYRAD/C1 - IRT measurements during precipitation events

The IRT measurement of sky/cloud temperature was in question during
precipitation events because rain or snow could accumulate in the
upward-pointed lens barrel. This was corrected by reorienting the
IRT to measure the sky temperature as reflected by a gold mirror.

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

NSA/SKYRAD/C1 - Noisy PIR data at Barrow

PIR1 data is noisy throughout the entire period, though there is still a definite signal 
through the noise.

• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Minima(down_long_hemisp_shaded1_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Standard
  Deviation(down_long_hemisp_shaded1_std)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Maxima(down_long_hemisp_shaded1_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp_shaded1)

• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Standard
  Deviation(down_long_hemisp_shaded1_std)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Minima(down_long_hemisp_shaded1_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp_shaded1)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1, Maxima(down_long_hemisp_shaded1_max)

NSA/SKYRAD/C1 - Downwelling IRT bias

The downwelling IRT was measuring higher sky/cloud temperatures than the AERI. The problem 
was corrected when the mirror was replaced.

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

NSA/SKYRAD/C1 - Tracker Inoperative

A blown fuse resulted in the tracker not shading the PIR and B&W
and the NIP not following the sun.

• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Standard Deviation(short_direct_normal_std)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(down_short_diffuse_hemisp_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer(short_direct_normal)

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

NSA/SKYRAD/C2 - 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):
Instr   Obstruction   AzStart   AzEnd
NIP     rad table     356       17
PSP     mfrsr         341       353

Note: There are a number of objects near the NW,N and NE horizon that may affect sunrise 
data near the summer soltice.

• PSP1 unshaded standard deviation(psp1_sd)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Minima(down_short_hemisp_min)
• PSP shaded standard deviation(psps_sd)
• PSP shaded mean(psps_mean)
• NIP maximum(nip_max)
• NIP mean(nip_mean)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer(down_short_hemisp)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Standard Deviation(short_direct_normal_std)
• PSP1 unshaded maximum(psp1_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Standard
  Deviation(down_short_hemisp_std)
• NIP minimum(nip_min)
• NIP standard deviation(nip_sd)
• PSP1 unshaded minimum(psp1_min)
• PSP shaded minimum(psps_min)
• PSP1 unshaded mean(psp1_mean)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Maxima(down_short_hemisp_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer(short_direct_normal)
• PSP shaded maximum(psps_max)

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

• Shortwave Direct Normal Irradiance, Pyrheliometer, Standard Deviation(short_direct_normal_std)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer(down_short_hemisp)
• NIP maximum(nip_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Standard
  Deviation(down_short_hemisp_std)
• NIP standard deviation(nip_sd)
• NIP minimum(nip_min)
• PSP1 unshaded minimum(psp1_min)
• PSP shaded maximum(psps_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer(short_direct_normal)
• NIP mean(nip_mean)
• PSP shaded minimum(psps_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Minima(down_short_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• PSP shaded mean(psps_mean)
• PSP1 unshaded maximum(psp1_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• PSP1 unshaded standard deviation(psp1_sd)
• PSP shaded standard deviation(psps_sd)
• PSP1 unshaded mean(psp1_mean)