NSA/SKYRAD/C2 - wrong calibration coefficent for PIRd in ATQ

Due to confusion over ARM calibration policy, a revised calibration was installed
and was in place for the duration of the time period indicated.  When the error
was noted, the original calibration was re-installed.

Users may notice discontinuities in PIRd data at the time boundaries of this
DQR.

• Instantaneous Downwelling Pyrgeometer Thermopile Voltage, Shaded Pyrgeometer(inst_down_long_hemisp_shaded_tp)

• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_shaded_std)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer(down_long_hemisp_shaded)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Minima(down_long_hemisp_shaded_min)

• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_shaded_std)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer(down_long_hemisp_shaded)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Maxima(down_long_hemisp_shaded_max)

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

NSA/SKYRAD/C1 - Shaded PIR data unreasonable

Scientificly unreasonable data values, the problem disappeared after the datalogger was 
exchanged with the spare. The data logger was exchanged on 11/7 at 20:10 GMT.

• PIR shaded maximum(pirs_max)
• PIR shaded standard deviation(pirs_sd)
• PIR shaded minimum(pirs_min)
• PIR shaded mean(pirs_mean)

• PIR shaded mean(pirs_mean)
• PIR shaded minimum(pirs_min)
• PIR shaded maximum(pirs_max)
• PIR shaded standard deviation(pirs_sd)

NSA/SKYRAD/C1 - Noise in Unshaded PIR data

Noise increased and an offset from shaded PIR became apparent during this period.

• PIR1 unshaded standard deviation(pir1_sd)
• PIR1 unshaded minimum(pir1_min)
• PIR1 unshaded maximum(pir1_max)
• PIR1 unshaded mean(pir1_mean)

• PIR1 unshaded minimum(pir1_min)
• PIR1 unshaded maximum(pir1_max)
• PIR1 unshaded mean(pir1_mean)
• PIR1 unshaded standard deviation(pir1_sd)

NSA/SKYRAD/C1 - NIP shaded by skyrad stand around local midnight

Around local midnight 9:30-10:30 GMT during summer clear sky the normal incidence 
pyranometer is shaded by the instrument stand.This causes the reading to be 0 W/m2. If cosine 
correction is applied for irradiance calulations this effect is negligible due to the low 
solar angle.

• NIP maximum(nip_max)
• NIP standard deviation(nip_sd)
• NIP minimum(nip_min)
• NIP mean(nip_mean)

• NIP maximum(nip_max)
• NIP standard deviation(nip_sd)
• NIP minimum(nip_min)
• NIP mean(nip_mean)

NSA/SKYRAD/C1 - PSP shaded by MFRSR after local midnight

Just past local midnight (11:00-11:40 GMT during summer clear sky) the global 
hemispherical pyranometer is shaded by the MFRSR instrument for about 40 minutes. This causes the 
reading to be 0 W/m2. This effect would be negligible in a daily average due to the low 
solar angle.

• PSP1 unshaded mean(psp1_mean)
• PSP1 unshaded minimum(psp1_min)
• PSP1 unshaded maximum(psp1_max)
• PSP1 unshaded standard deviation(psp1_sd)

• PSP1 unshaded maximum(psp1_max)
• PSP1 unshaded standard deviation(psp1_sd)
• PSP1 unshaded mean(psp1_mean)
• PSP1 unshaded minimum(psp1_min)

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 Infra Red Temperature Minima(sky_ir_temp_min)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky 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 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 - NSA B&W nighttime offset in Barrow too large

This problem only became apparent as NSA C1 nights became long enough for full darkness. 
The shaded global diffuse instrument (Eppley 8-48) showed a negative nighttime offset 
larger than the expected 0 to -4 W/m2. Typically -5 to -8 W/m2. This size of offset is not 
uncommon with Eppley PSPs but not observed with Eppley 8-48s.  The problem was corrected 
with replacement of mounting screws which were creating a ground loop.

• PSP shaded minimum(psps_min)
• PSP shaded maximum(psps_max)
• PSP shaded mean(psps_mean)
• PSP shaded standard deviation(psps_sd)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Standard Deviation(down_short_diffuse_hemisp_std)

• 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)
• PSP shaded maximum(psps_max)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• PSP shaded minimum(psps_min)
• PSP shaded mean(psps_mean)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• PSP shaded standard deviation(psps_sd)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Standard Deviation(down_short_diffuse_hemisp_std)

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, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Down-welling unshaded pyranometer voltage(down_short_hemisp)
• NIP maximum(nip_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, 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, Pyrgeometer(short_direct_normal)
• NIP mean(nip_mean)
• PSP shaded minimum(psps_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Minima(short_direct_normal_min)
• PSP shaded mean(psps_mean)
• PSP1 unshaded maximum(psp1_max)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Maxima(short_direct_normal_max)
• PSP1 unshaded standard deviation(psp1_sd)
• PSP shaded standard deviation(psps_sd)
• PSP1 unshaded mean(psp1_mean)