TWP/SKYRAD/C3 - Reprocess: PIR identified as unshaded is really shaded

From the initial installation of the Darwin SKYRAD suite of instruments, two shaded PIRs 
were installed rather than one shaded and one unshaded PIR as 
documented in the netcdf header information.

• Instantaneous Downwelling Pyrgeometer Dome Thermistor Temperature, Pyrgeometer2(inst_down_long_hemisp2_dome_temp)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Minima(down_long_hemisp2_min)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Maxima(down_long_hemisp2_max)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2(down_long_hemisp2)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Temperature, Pyrgeometer2(inst_down_long_hemisp2_case_temp)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Standard Deviation(down_long_hemisp2_std)
• Instantaneous Downwelling Pyrgeometer Thermopile, Pyrgeometer2(inst_down_long_hemisp2_tp)

TWP/SKYRAD/C3  - IRT incorrect min/delta values

For field sky_ir_temp, the value of valid_min was incorrectly assigned to -49.7 C and no 
value of valid_delta was assigned. The actual values should be -60 and 50 C, respectively.

• 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)

TWP/SKYRAD/C3 - Incorrect NIP cal coefficient

During our site visit comparison at Darwin we observed that the skyrad NIP was reading 
about 50 w/m2 lower than the comparison cavity radfiometer and the replacement NIP on the 
comparison stand. We found that the calibration coefficient for the NIP (responsivity at 
45o)was put in as 8.64X10-6. The NIP was new and had not been calibrated at SGP. The 
factory number was 8.04X10-6. We corrected the calibration coefficient and the instruments 
agreed to better than 5 w/m2.

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

TWP/SKYRAD/C3 - Reprocess: NIP calibrations incorrect

On 05/20 during installtion of the new Campbell datalogger system and associated program 
the NIP (S/N 33551E6) was assigned an incorrect calibration coefficient.  A coefficient of 
116.01 W/m2/mV was applied when it should have been 124.378 W/m2/mV.
TWP reports SV0405D and SV0409D detail the activities which lead to this DQR.

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

• null(Raw data stream - documentation not supported)

TWP/SKYRAD/C3 - tracker inoperative

A lightning strike at Darwin removed the tracker from service.  Instruments installed on 
the tracker were rendered either inoperative or were not shaded during this time period.  
The longwave hemispheric instruments PIR1 and PIR2 appear to have been unaffected.  They 
are not suseptable to incorrect tracker operation.  The downwelling hemispheric shortwave 
PSP instrument mounted on Skyrad will not be affected by incorrect tracker operation.

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

• Instantaneous Direct Normal Shortwave Irradiance, Pyheliometer Thermopile
  Voltage(inst_direct_normal)
• Instantaneous Uncorrected Downwelling Shortwave Diffuse, Shaded Pyranometer
  Thermopile Voltage(inst_diffuse)

• null(Raw data stream - documentation not supported)

TWP/SKYRAD/C3 - IRT damaged

The analog output of the IRT was damaged by a lightning strike. The problem was corrected 
by replacing the instrument with a spare. The damaged IRT was returned to the vendor for 
repair.

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

• Instantaneous Sky/Cloud Infrared(inst_sky_ir_signal)

TWP/SKYRAD/C3 - NIP Failure

Skyrad normal incident shortwave irradiance (NIP) started reporting impossible values for 
direct normal irradiance starting 16 November approx 2100GMT corresponding to a rain 
event at the same time.

The NIP was replaced fixing the problem.

Direct normal data are not recoverable.  However, the NIP data can be calculated from the 
global hemsipherical shortwave and global hemispherical diffuse datastreams by using the 
following relationship:
Global Horizontal = Direct Normal x cos(Z) + Diffuse Horizontal 
where Z is the zenith angle.

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

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

TWP/SKYRAD/C3 - NIP instrument failure

The NIP (Short Direct Normal) was replaced after it displayed symptoms of failure 
associated with either unknown precipitation related issues or a possible lightning strike.

NIP data are not recoverable.  Direct normal data can be reconstructed from global 
hemispheric and global diffuse data using the following relationship:
   global hemispheric = direct*cos(sza) + diffuse hemispheric

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

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

• null(Raw data stream - documentation not supported)

TWP/SKYRAD/C3 - IRT power supply

The 12-to-24V DC converter the provides power to the IRT had shut down and was restarted 
by power-cycling.

• 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)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)

TWP/SKYRAD/C3 - Contamination

The IRT exhibited a positive bias compared to AERI. The problem was corrected when the 
lens and mirror were cleaned.

• 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)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)

TWP/SKYRAD/C3 - Direct normal instrument failure

The NIP instrument (short_direct_normal data stream) failed giving bad data during this 
time period.  The failure start time coincides with a reported DC power failure but no 
connection between the reported power failure and the failure of this instrument could be 
determined. 

Ops also reported the tracker clock running 2.9 minutes slow during maintenance on 12/22 
0300GMT (see CS-2008-0714).  Again, the slow clock is not suspect and did not appear to 
affect alignment.

Ops replaced the NIP instrument on 12/30 and short_direct_normal data resumed normal 
operation.

Disregard the short_direct_normal (NIP) data during this time period or calculate using 
the global and diffuse instruments and the following relationship:
short_direct_normal = ((down_short_hemisp - down_short_diffuse_hemisp))/cos(zenith angle)

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

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

TWP/SKYRAD/C3 - Tracker inoperative

The tracker at Darwin failed 01/23.  The tracker was power cycled on 01/27 and it returned 
to normal operation.

The affected data streams are short_direct_normal (NIP) and down_short_diffuse_hemisp 
(8-48).  

The down_short_hemisp are not affected.  

The down_long_hemisp1 and 2 (PIR1 and PIR2) should not be affected but direct sun can 
affect individual instrument performance.

• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Minima(down_long_hemisp2_min)
• Shortwave Direct Normal Irradiance, Pyrgeometer(short_direct_normal)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Maxima(down_long_hemisp2_max)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer1, Maxima(down_long_hemisp1_max)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer1, Minima(down_long_hemisp1_min)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Standard Deviation(down_short_diffuse_hemisp_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Instantaneous Downwelling Pyrgeometer Thermopile, Pyrgeometer1(inst_down_long_hemisp1_tp)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Temperature, Pyrgeometer2(inst_down_long_hemisp2_case_temp)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Standard Deviation(down_long_hemisp2_std)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Temperature, Pyrgeometer2(inst_down_long_hemisp2_dome_temp)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Temperature, Pyrgeometer1(inst_down_long_hemisp1_case_temp)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer1, Standard Deviation(down_long_hemisp1_std)
• Instantaneous Downwelling Pyrgeometer Thermopile, Pyrgeometer2(inst_down_long_hemisp2_tp)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Minima(short_direct_normal_min)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Temperature, Pyrgeometer1(inst_down_long_hemisp1_dome_temp)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2(down_long_hemisp2)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer1(down_long_hemisp1)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Maxima(short_direct_normal_max)

• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Pyrgeometer1(inst_down_long_hemisp1_case_resist)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Pyrgeometer2(inst_down_long_hemisp2_case_resist)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Pyrgeometer1(inst_down_long_hemisp1_dome_resist)
• Instantaneous Downwelling Pyrgeometer Thermopile, Pyrgeometer1(inst_down_long_hemisp1_tp)
• Instantaneous Downwelling Pyrgeometer Thermopile, Pyrgeometer2(inst_down_long_hemisp2_tp)
• Instantaneous Direct Normal Shortwave Irradiance, Pyheliometer Thermopile
  Voltage(inst_direct_normal)
• Instantaneous Uncorrected Downwelling Shortwave Diffuse, Shaded Pyranometer
  Thermopile Voltage(inst_diffuse)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Pyrgeometer2(inst_down_long_hemisp2_dome_resist)