PYE/SKYRAD/M1 - Reprocessed: Installation problems

The installation of the SKYRAD instrument was not without problems.  During all or part of 
the time period specified the calibrations were incorrect or incomplete, the downwelling 
diffuse and direct normal leads were switched, and the shadowband was severely out of 
alignment.

These data have been reprocessed to apply corrections as follows:

1) NIP & PSP-diffuse leads swapped 20050214-20050412.1645
     - swapped the NIP and PSP columns in the raw data files
     - backed out the original, incorrect calibrations 
     - applied correct calibrations
2) PSP-diffuse calibration error 050214-050215
     - backed out the original, incorrect calibration
     - applied correct calibrations
3) PSP-DS cal error 050214-050215
     - backed out the original, incorrect calibration
     - applied correct calibration
4) NIP cal error 050214-050215 and 050218-050401
     - backed out the original, incorrect calibrations
     - applied correct calibration

The reprocessed data were archived in February, 2007.

Users are encouraged to still use these data with caution only after a thorough quality 
review to be certain the data meet their requirements.

• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• inst_down_long_shaded1_case_temp
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• down_long_hemisp_shaded2_min
• inst_down_long_shaded2_dome_temp
• IR Brightness Temperature(sky_ir_temp)
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• sky_ir_temp_max
• short_direct_normal_std
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• down_long_hemisp_shaded1_min
• down_long_hemisp_shaded1_std
• sky_ir_temp_std
• sky_ir_temp_min
• inst_down_long_shaded2_case_temp
• down_long_hemisp_shaded2_max
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• down_short_diffuse_hemisp_std
• down_long_hemisp_shaded2_std
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• inst_down_long_shaded1_dome_temp
• down_short_hemisp_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• down_long_hemisp_shaded1_max
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)

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

PYE/SKYRAD/M1 - Reprocessed: IRT configuration and calibration

The configuration of the IRT was inadvertently set to default and the program of the data 
loggers were changed to that used at TWP.C3.  This caused the calibration of the data to 
be wrong. It was corrected by reconfiguring the IRT and changing the conversion factors 
in the data logger program.

These data have been reprocessed to apply correct calibrations and the reprocessed data 
were archived in February, 2007.

• sky_ir_temp_std
• sky_ir_temp_min
• sky_ir_temp_max
• IR Brightness Temperature(sky_ir_temp)

• Raw data stream - documentation not supported

• inst_sky_ir_signal

PYE/SKYRAD/M1 - IRT bias

The SKYRAD IRT measured lower sky temperatures than the AERI.  This may have been due to a 
dirty mirror or lens.

• sky_ir_temp_std
• sky_ir_temp_min
• sky_ir_temp_max
• IR Brightness Temperature(sky_ir_temp)

NIM/SKYRAD/M1 - IRTs do not agree with AERI

Since deployment at PYE, and then at NIM, the AMF SKYRAD IRT measured about 10K higher sky 
temperatures than the AERI and the MWRP IRT measureed about 20K higher than the AERI.  
Several actions were taken to diagnose the problem including confirming the correct 
configuration of the IRTs and data logger, cleaning the mirror and lens, and replacing the mirror.

After several days of rain beginning 6/2/2006, the three instruments came into agreement. 
It is unknown whether this was a problem with the AERI, MWRP-IRT or SKYRAD-IRT.

• sky_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_max

NIM/SKYRAD/M1 - Instrument ventilator problem

Data quality office first reported that PIR1 and PIR2 appear to be deviating more than 
typical during the daylight hours.  It was found that the Skyrad PIR ventilator fans were 
building up debris on the intake air filter.  Obstructed air flow results in solar heating 
of the PIR ventilator housing in the later part of the day and biasing the incomming IR 
irradiance values. The slow buildup was insidious and wasn't discovered and corrected 
(i.e. ventilator fans cleaned on a regular and frequent basis) until Feb 23rd. On or around 
December 23rd was when this problem may have first started.  We are unable to quantify the 
extent of the problem in W/m2.  Normal deviation between PIRs is typically 3-5 W/m2.

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

• inst_down_long_shaded2_dome_temp
• down_long_hemisp_shaded1_std
• down_long_hemisp_shaded1_min
• down_long_hemisp_shaded1_max
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• down_long_hemisp_shaded2_min
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• down_long_hemisp_shaded2_max
• inst_down_long_shaded1_dome_temp
• down_long_hemisp_shaded2_std
• inst_down_long_shaded2_case_temp
• inst_down_long_shaded1_case_temp
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)

• Raw data stream - documentation not supported

NIM/SKYRAD/M1 - 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.

• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)

PYE/SKYRAD/M1 - 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.

• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)

NIM/SKYRAD/M1 - Unknown problem with PIR1

Spikes in Shaded 1 occur frequently during this time period, resulting in differences b/t 
shaded1 and shaded2 exceeding 20W/m2.  Instrument connections were checked and a spare 
PIR instrument was tried in the place of PIR1 (shaded1).  After returning the original PIR1 
to its original location data again looked good and very close to PIR2.  Problem appears 
resolved but exact cure is unknown.

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

• inst_down_long_shaded2_dome_temp
• down_long_hemisp_shaded1_std
• down_long_hemisp_shaded1_min
• down_long_hemisp_shaded1_max
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• down_long_hemisp_shaded2_min
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• down_long_hemisp_shaded2_max
• inst_down_long_shaded1_dome_temp
• down_long_hemisp_shaded2_std
• inst_down_long_shaded2_case_temp
• inst_down_long_shaded1_case_temp
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)

• Raw data stream - documentation not supported

NIM/SKYRAD/M1 - Tracker inoperative

Starting on 9/12 the NIM radiometer tracker drifted enough due to sinking supports and a 
drifting clock that the direct normal measurments (NIP) and the downwelling hemispheric 
diffuse shortwave measurments (8-48) were adversely affected in the afternoon hours.  The 
shortwave hemispheric global instrument (PSP) and downelling hemispheric longwave shaded1 
and shaded2 (PIR) are unaffected by this problem. 

The tracker problem greatly affected direct measurements and affected the diffuse 
measurement to a lesser extent. There are no redundant measurements for these instruments.  
However, during this time range the data collected before local noon (aprox 1140GMT) for all 
shortwave Skyrad instruments appear to be good.

• inst_diffuse
• inst_direct_normal

• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• down_short_diffuse_hemisp_std
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• short_direct_normal_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)

• Raw data stream - documentation not supported

PYE/SKYRAD/M1 - Datalogger program error affected downwelling longwave

The excitation delays used in measuring the PIR1 case thermistor, "Case1", and the PIR2 
dome thermistor, "Dome2", were discovered to have been incorrectly set to 0 in the Skyrad 
datalogger program when the new CR23X based Skyrad loggers were installed.  The result of 
no delay in these measurements results in an error in the measured resistance of the 
thermistors, Case1 and Dome2, and thus the calculated PIR1 and PIR2 irradiances.  The 
absolute value of the errors are inversely proportial to temperature.

At Pt Reyes, we are unable to determine if the excitation delay problem was present.  The 
first Skyrad datalogger program installed at PYE was correct but later versions modified 
and uploaded in March and April of 2005 may have had the Delay0 problem.

The problem also can not be determined from the data.  Pt. Reyes temperature fluctuations 
throughout the year are maritime and fall into a relatively narrow range in 2005 between 
2.5-20C.  The Delay0 problem introduces larger errors into PIR1 and PIR2 irradiance 
calculations as the temperature drops.  At the lowest temperature at Pt Reyes in 2005 (approx 
2.5C occurring in March) the largest PIR1 error would be -.48 W/m2 and PIR2 +.38 W/m2.  
The scale of these errors are smaller than the resolution of the instrument and are lost 
in the normal variation of the instrument readings. Cursory review of the thermistor data 
during cold periods does not show any discernable biases.  Furthermore, the data logger 
programming "error" due to the Delay0 problem is an order of magnitude less than the total 
estimated measurement uncertainty of the pyrgeometer data from any ARM installation (+/- 
5 W/sq m for 4-coeff and +/- 10 W/sq m for 2-coeff calibrations).

Due to these issues, no Delay0 corrections will be applied to PYE Skyrad data.

• inst_down_long_shaded2_case_temp
• down_long_hemisp_shaded2_max
• down_long_hemisp_shaded2_std
• inst_down_long_shaded1_dome_temp
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• inst_down_long_shaded1_case_temp
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• down_long_hemisp_shaded2_min
• inst_down_long_shaded2_dome_temp
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• down_long_hemisp_shaded1_max
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• down_long_hemisp_shaded1_min
• down_long_hemisp_shaded1_std

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

NIM/SKYRAD/M1 - station setup and troubleshooting

This station was collecting data for the first time at this location - There were multiple 
instrument setup problems (PIR cabling, IRT setup, tracker operation)that were being 
corrected during this time.  Radiometer data is unreliable during this period.

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

• inst_down_long_shaded2_dome_temp
• down_long_hemisp_shaded1_std
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• down_long_hemisp_shaded1_min
• down_long_hemisp_shaded1_max
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• down_short_hemisp_std
• inst_down_long_shaded1_dome_temp
• down_long_hemisp_shaded2_std
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• inst_down_long_shaded2_case_temp
• short_direct_normal_std
• inst_down_long_shaded1_case_temp
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• sky_ir_temp_max
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• IR Brightness Temperature(sky_ir_temp)
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• down_long_hemisp_shaded2_min
• down_long_hemisp_shaded2_max
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• sky_ir_temp_min
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• down_short_diffuse_hemisp_std
• sky_ir_temp_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)

• Raw data stream - documentation not supported

FKB/SKYRAD/M1 - Instrument setup incorrect data

FKB station initial setup and configuration - all radiometer data before the end date of 
this time range is suspect. If this data is needed refer to DQ flags and manual assessment 
to determine if data is usable.

• alt
• inst_down_long_hemisp2_dome_resist
• inst_down_long_hemisp2_case_resist
• inst_direct_normal
• lat
• inst_global
• inst_diffuse
• inst_down_long_hemisp1_case_resist
• inst_down_long_hemisp1_tp
• base_time
• inst_down_long_hemisp1_dome_resist
• inst_down_long_hemisp2_tp
• time
• time_offset
• inst_sky_ir_signal
• lon

• Raw data stream - documentation not supported

• lon
• sky_ir_temp_std
• down_long_hemisp1_min
• sky_ir_temp_min
• base_time
• down_long_hemisp2_max
• logger_temp
• down_long_hemisp2_std
• vBatt
• time_offset
• lat
• sky_ir_temp_max
• inst_down_long_hemisp2_tp
• time
• inst_down_long_hemisp2_dome_temp
• inst_down_long_hemisp1_case_temp
• down_long_hemisp2_min
• down_long_hemisp1_max
• down_long_hemisp1_std
• inst_down_long_hemisp1_dome_temp
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• short_direct_normal_std
• down_short_hemisp_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• alt
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• inst_down_long_hemisp1_tp
• down_short_diffuse_hemisp_std
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• inst_down_long_hemisp2_case_temp
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• IR Brightness Temperature(sky_ir_temp)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)

FKB/SKYRAD/M1 - IRT bias

On several days (especially in April, September, and December), the sky temperature 
measurement from the IRT exhibited a positive bias from the AERI measurement from about 20:00 
to 07:00. This diurnal variation is highly correlated with the measurement of relative 
humidity so was most-likely due to the contribution of the temperature of water vapor, fog, 
and/or condensation on the lens and/or mirror.

• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_min
• sky_ir_temp_max

HFE/SKYRAD/M1 - IRT bias

The sky temperatures exhibited a positive bias compared to AERI, especially when < 230K. 
This is indicative of an incorrect emissivity setting (to compensate for the gold mirror) 
or a poor calibration. A similar problem with the same instrument occurred during the FKB 
deployment that was attributed to water vapor.

• sky_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_max

GRW/SKYRAD/M1 - Tracker inoperative

The solar tracker arms were caught and pulled way out of alignment. Problem corrected by 
OPs at 0815Z May 11th.  All bolts tightened and alignment and tracking checked. 

Down_short_hemisp_diffuse (8-48 instrument)is incorrect and not recoverable. 
short_direct_normal (NIP instrument) is suspect during this time as well.  down_short_hemisp (PSP 
instrument) was unaffected.

• inst_direct_normal
• inst_diffuse

• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• down_short_diffuse_hemisp_std
• short_direct_normal_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)

GRW/SKYRAD/M1 - Reprocessed: IRT configuration

The SKYRAD IRT was used in testing a revised serial communication program. During the 
testing, the analog output configuration was to changed to default values (used at TWP and 
NSA sites) that are different than those used at AMF. So, the IRT's analog output was set 
to a scale of 25K/V and an offset of 213.2K but the logger converted the signal using a 
scale of 26K/V and an offset of 173.2K. 

The sky temperature measurements were corrected using the following equation

        Tnew = (25/26)(Told-173.2K)+213.2K

and the data were reprocessed.  The reprocessed data were archived in April 2011.

• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_min
• sky_ir_temp_max

GRW/SKYRAD/M1 - Possible dirty dome

The difference between downwelling shortwave hemispheric irradiance and derived 
downwelling shortwave hemispheric irradiance was larger than normal (>50W/m2) and was most 
noticeable at lower zenith angles.  The problem spontaneously resolved itself on 7/16 without any 
specific callouts by the GRW cleaning personnel on their reports.  Short_direct_normal 
datastream is suspected to be low due to potentially dirty NIP instrument window during 
this time period.  The commencement of this problem corresponds with a rain event early 
7/12. The possibility of other radiometers affected by dirty domes is also possible. 
Longwave instruments are typically immune to this level of contamination.

• inst_global
• inst_diffuse
• inst_direct_normal

• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_hemisp_std
• down_short_diffuse_hemisp_std
• short_direct_normal_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)

GRW/SKYRAD/M1 - Daily brief instrument shading

Due to the persistent cloudy conditions at this site this shading of the NIP and PSP is 
rarely evident in the data. But from approximately 1745 to 1810 GMT from 8/26 to 10/23 and 
from 3/01 to 4/18 during the AMF deployment years 2009 and 2010, the NIP and PSP are 
shaded by the 10m met tower to the SE of the Skystand. 

Data review indicates that the NIP (short_direct_normal) and PSP (down_short_hemisp) are 
shaded by a single tower pole and possibly other tower mounted objects.  The data are not 
correctable but the azimuth and zenith windows to avoid are:
short_direct_normal (NIP instrument)
	     Zenith angle > 62 deg
  254 deg < Azimuth angle < 262 deg
primary obstruction at 255 deg Az

down_short_diffuse(PSP instrument)
	     Zenith angle > 59 deg
  246 deg < Azimuth angle < 257 deg
primary obstruction at 251.5 deg Az


Date ranges this problem will exist for are:
20090301-20090418 (pre-official deployment, data exist)
20090826-20091023
20100301-20100418
20100826-20101023

The QCrad VAP should flag bad data points via its QC logic.  Users should either exclude 
the data within the windows above or review data for outliers in these zenith, azimuth 
angles.

• inst_direct_normal
• inst_global

• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• down_short_hemisp_std
• short_direct_normal_std
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)

GRW/SKYRAD/M1 - IRT grounding

The IRT analog output line appears to have adversely affected the
SKYRAD datalogger grounding.  This resulted in intermittent anomalous readings across all 
SKYRAD datalogger channels including logger voltage.

The problem was corrected by regrounding the analog cable.

• inst_down_long_hemisp2_case_resist
• inst_down_long_hemisp1_dome_resist
• inst_down_long_hemisp1_tp
• inst_down_long_hemisp2_dome_resist
• inst_global
• inst_diffuse
• inst_down_long_hemisp2_tp
• inst_sky_ir_signal
• inst_down_long_hemisp1_case_resist
• inst_direct_normal

• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• inst_down_long_hemisp1_case_temp
• short_direct_normal_std
• sky_ir_temp_max
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• down_long_hemisp2_min
• down_long_hemisp2_max
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• IR Brightness Temperature(sky_ir_temp)
• inst_down_long_hemisp2_tp
• logger_temp
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_hemisp_std
• down_short_diffuse_hemisp_std
• sky_ir_temp_std
• sky_ir_temp_min
• inst_down_long_hemisp2_case_temp
• inst_down_long_hemisp1_dome_temp
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• inst_down_long_hemisp1_tp
• vBatt
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• down_long_hemisp2_std
• inst_down_long_hemisp2_dome_temp
• down_long_hemisp1_std
• down_long_hemisp1_max
• down_long_hemisp1_min

GRW/SKYRAD/M1 - AOS tower Obstruction

Due to the persistent cloudy conditions at this site the shading is rarely evident in the 
data. But at approximately 1010GMT everyday during from approximately 12/2/2009 to 
1/11/2010 the NIP is shaded by the AOS tower.  Data review indicates that only the NIP 
(short_direct_normal) is obstructed when the sun is at 130 to 132 deg azimuth during the time 
period specified.

NIP data are not recoverable.  However, short_direct_normal can be reconstructed by 
applying the following formula:

Short_direct_normal = (down_short_hemisp-down_short_diffuse_hemisp)/cos(Zenith angle)

• inst_direct_normal

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• short_direct_normal_std

GRW/SKYRAD/M1 - Short direct normal questionable

Starting on 05/08/2010 values of short_direct_normal from the NIP instrument were reading 
low (up to 50W/m2).  This was most apparent during sunny/partly sunny periods.  The 
values spontaneously returned to normal on 5/14 with no Ops intervention.  Data system checks 
after that date revealed no apparent problems with instruments or datalogger. The problem 
has not recurred.

Only the short_direct_normal values during this time period are suspect.  If direct normal 
values are needed they can be re-constructed using the following relationship for each 
minute of data:
down_short_hemisp = short_direct_normal * cos(zenith angle) + down_short_diffuse_hemisp

• inst_direct_normal

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• short_direct_normal_std

GAN/SKYRAD/M1 - Degraded IRT mirror

The gold mirror was worn and needed to be replaced. Degradation of the mirror occurs 
gradually and it is difficult to determine when it begins to affect the measurement. To 
estimate the beginning of the problem, I used the time when the difference in IR sky 
temperature from the MWR3C was consistantly greater that 2.4K (2 times the resolution of the IRT 
measurement).

The problem was corrected when the mirror was replaced.

• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_std
• sky_ir_temp_min
• sky_ir_temp_max

GAN/SKYRAD/M1 - PIR2 failure

Increasing difference between PIR1 and PIR2 beginning December 12.  Suspected problem with 
PIR2 thermistor bridge or instrument thermistor.  OPS replaced PIR2 unit with a spare. 
The data from PIR2 after replacement appears to be normal.

• down_long_hemisp2_max
• down_long_hemisp2_min
• inst_down_long_hemisp2_case_temp
• down_long_hemisp2_std
• inst_down_long_hemisp2_tp
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• inst_down_long_hemisp2_dome_temp

• inst_down_long_hemisp2_case_resist
• inst_down_long_hemisp2_tp
• inst_down_long_hemisp2_dome_resist

SBS/SKYRAD/M1 - Noise in downwelling SW hemispheric

Downwelling Shortwave Hemispheric signal varies wildly between missing (-9999) and large 
positive values over this period.

• inst_global

• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• down_short_hemisp_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)

GAN/SKYRAD/M1 - PIR1 failure

PIR1 irradiance data are incorrect beginning Feb 4th and questionable as far back as Jan 
31st around 0400 UTC.  Site operations ceased Feb 9 before repairs were made.

• inst_down_long_hemisp1_tp
• inst_down_long_hemisp1_case_temp
• down_long_hemisp1_std
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• inst_down_long_hemisp1_dome_temp
• down_long_hemisp1_min
• down_long_hemisp1_max

• inst_down_long_hemisp1_tp
• inst_down_long_hemisp1_case_resist
• inst_down_long_hemisp1_dome_resist

PVC/SKYRAD/M1 - Intake Fan Failure

PSP (down_short_hemisp) ventilator fan failed from start of PVC deployment.  Site ops 
repaired/replaced on 8/28. Instrument data are not recoverable.

The down_short_hemisp data are not recoverable but can be re-constructed using the 
short_direct_normal and down_short_diffuse_hemispheric measurements and the following formula: 

Global = Direct * cos(zenith angle) + Diffuse

• inst_global

• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• down_short_hemisp_std

PVC/SKYRAD/M1 - Reprocessed: Incorrect calibration coefficients

Incorrect programs were used in Skyrad since PVC deployment period began.  The Skyrad 
program was corrected 09/05/2012 approx 20:00GMT. Reprocessing will be required of all 
instruments at this station except the IRT. This will require applying the following 
corrections for the time range specified. 
Serial numbers(incorrectly applied): 
PIR1-DIR: 34306
PIR2-DIR: 34303
Diffuse PSP: 34284
NIP: 34097
PSP-DS: 34293

Serial numbers(correct): 
PIR1-DIR: 34303
PIR2-DIR: 34306
Diffuse PSP: 35751
NIP: 37285
PSP-DS: 37302
    
Data: 
Longwave requires reprocessing using the 20second datastream and applying the following k1 
coefficients (note: the longwave instruments were swapped according to datalogger).
down_long_hemisp1 (old cal) = 0.23041
down_long_hemisp1 (corr cal) = 0.24750
down_long_hemisp2 (old cal) = 0.24750
down_long_hemisp2 (corr cal) = 0.23041

Shortwave only requires application of the following corrections to 1min and 20 second 
data.
down_short_diffuse_hemisp(corr) = down_short_diffuse_hemisp(old value)*(104.45(corr 
cal)/120.91(incorr cal))
short_direct_normal(corr) = short_direct_normal(old value)*(117.25(new cal)/124.97(incorr 
cal))
up_short_hemip(corr) = up_short_hemip(old value)*(119.21(new cal)/108.48(incorr cal))

Contact radiometer mentor with any comments/questions

Reprocessing completed 20121217

• inst_down_long_hemisp1_case_resist
• inst_global
• inst_diffuse
• inst_direct_normal
• inst_down_long_hemisp2_case_resist
• inst_down_long_hemisp2_dome_resist
• inst_down_long_hemisp1_dome_resist
• inst_down_long_hemisp1_tp
• inst_down_long_hemisp2_tp

• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• down_long_hemisp2_std
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• inst_down_long_hemisp2_case_temp
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• inst_down_long_hemisp2_tp
• down_long_hemisp1_max
• down_long_hemisp2_min
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_long_hemisp1_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• down_short_diffuse_hemisp_std
• short_direct_normal_std
• down_long_hemisp2_max
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• down_short_hemisp_std
• inst_down_long_hemisp2_dome_temp
• inst_down_long_hemisp1_case_temp
• inst_down_long_hemisp1_dome_temp
• down_long_hemisp1_min
• inst_down_long_hemisp1_tp

PVC/SKYRAD/M1 - Reprocess: Incorrect IRT Configuration

The SKYRAD IRT was installed temporarily (waiting for the new enclosure) in
a vertical orientation, without the use of the gold mirror. When irt_comm
was started, the emissivity parameter in the startup file was not changed to 1.000 
compensate for the absence of the mirror, resulting in a positive bias of about 5 K.

These data may be corrected by adjusting the radiance values for the difference in 
emmissivity.

• sky_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_max

PVC/SKYRAD/M1 - IRT failure

The IRT failed because of water intrusion.

• inst_sky_ir_signal

• sky_ir_temp_std
• sky_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_max

PVC/SKYRAD/M1 - IRT scale factor

The IRT was replaced with a unit with the wrong analog output configuration, such that the 
sky temperature was below the measurable range, resulting in a constant output of 0 
volts or 173.2 K.

• inst_sky_ir_signal

• sky_ir_temp_std
• sky_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_max

PGH/SKYRAD/M1 - Reprocess: Incorrect calibrations

During the entire India deployment the Skyrad system was configured with incorrect 
calibration coefficients for the shortwave instruments. The program hadn't been updated since 
the previous deployment in the Azores.

The instrument mentor, site personal and OSS support have attempted to best determine the 
serial numbers of instruments installed at PGH during the deployment period.  The 
following instrument data will need to be reprocessed with the following correction multipliers:

PIR1-DIR(down_long_hemisp1): OK, no correction required
PIR2-DIR(down_long_hemisp2): OK, no correction required
Diffuse 8-48 (down_short_diffuse): 116.95(correct)/120.91(incorrect) = .96725
NIP (short_direct_normal): 127.03(correct)/124.97(incorrect) = 1.01648
PSP-DS (down_short_hemsip): 111.29(correct)/108.48(incorrect) = 1.02590
IRT: calibration should be validated by instrument mentor (Vic Morris): mult=26, 
offset=173.2

Correct serial numbers:   
Diffuse 8-48 (down_short_diffuse): 34066
NIP (short_direct_normal): 34135E6
PSP-DS (down_short_hemsip): 33942F3

• inst_global
• inst_diffuse
• inst_sky_ir_signal
• inst_direct_normal

• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• down_short_hemisp_std
• IR Brightness Temperature(sky_ir_temp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• sky_ir_temp_min
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• sky_ir_temp_max
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• sky_ir_temp_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• down_short_diffuse_hemisp_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• short_direct_normal_std

PVC/SKYRAD/M1 - Instrument noise

All instruments on Skyrad exhibit intermittant erratic behavior from 10/05 through 10/23. 
Appears to have been an grounding issue with the IRT installed on Skyrad and replaced 
10/17. After the last problem period on 10/23 the problem resolved itself without operator 
involvement.

All data on Skyrad during these erratic behaviour periods are not recoverable. Bad data 
can generally be identified by screening vBatt for values outside normal operation range of 
13.3-13.6V.

• inst_down_long_hemisp1_case_resist
• inst_global
• inst_diffuse
• inst_sky_ir_signal
• inst_direct_normal
• inst_down_long_hemisp2_case_resist
• inst_down_long_hemisp1_dome_resist
• inst_down_long_hemisp2_dome_resist
• inst_down_long_hemisp1_tp
• inst_down_long_hemisp2_tp

• sky_ir_temp_std
• sky_ir_temp_min
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• down_long_hemisp2_std
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• inst_down_long_hemisp2_case_temp
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• inst_down_long_hemisp2_tp
• down_long_hemisp1_max
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_long_hemisp2_min
• down_long_hemisp1_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• down_short_diffuse_hemisp_std
• down_long_hemisp2_max
• short_direct_normal_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• down_short_hemisp_std
• inst_down_long_hemisp2_dome_temp
• inst_down_long_hemisp1_case_temp
• inst_down_long_hemisp1_dome_temp
• IR Brightness Temperature(sky_ir_temp)
• down_long_hemisp1_min
• sky_ir_temp_max
• inst_down_long_hemisp1_tp

PVC/SKYRAD/M1 - IRT disconnected

The IRT was disconnected to diagnose PIR signal noise.

• sky_ir_temp_std
• sky_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_max