TWP/GNDRAD/C3 - IRT bias

The IRT behaved erratically, jumping frequently from reporting about 50 Wm^(-2) higher 
than the PIR for surface irradiance values to about 100Wm^(-2) lower than the PIR.  
Generally, the IRT measured lower surface temperatures than expected from the PIR.

• Effective Surface (Skin) Temperature(sfc_ir_temp)
• sfc_ir_temp_std
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)

TWP/GNDRAD/C3 - Tower inverted for instrument testing and replacement

The tower at Darwin was brought down to test and replace the Gndrad PIR on 8/5/2005 and 
the PSP on 8/9/2005

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

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

• inst_direct_normal
• inst_diffuse

• Raw data stream - documentation not supported

TWP/SKYRAD/C3 - Reprocess: Incorrect datalogger program affecting PIR1 and PIR2 
downwelling longwave

The excitation delays using in measuring the PIR1 case thermistor commonly named "Case1" 
and the PIR2 dome thermistor called "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 errors are inversely proportial to temperature.

Users can apply temperature dependent irradiance corrections as shown in the table below.  
Recall that the reported uncertainty of PIRs is typically +-.25% to +-.5% or 1 to 2 
W/m2. The error corrections become the same order of magnitude or larger than the instrument 
uncertainties at or below 260K or 9F. Irradiance Correction Table for Skyrad (TWP and 
NSA) DIR1 and DIR2 Irradiance

		DIR1	DIR1	DIR2	DIR2
	T[F]	Tcase[K]	Correction[W/m2]	Tdome[K]       
		Correction[W/m2]
	109.4	316.13	0.00	316.13	0.00
	100.5	311.20	-0.15	311.20	0.12
	93.2	307.14	-0.12	307.14	0.10
	87.0	303.70	-0.10	303.70	0.08
	81.6	300.70	-0.17	300.70	0.14
	77.0	298.15	-0.22	298.15	0.18
	59.4	288.35	-0.34	288.35	0.27
	47.4	281.72	-0.23	281.72	0.18
	38.5	276.74	-0.42	276.74	0.34
	31.3	272.77	-0.48	272.77	0.38
	25.4	269.48	-0.61	269.48	0.49
	20.3	266.67	-0.67	266.67	0.54
	16.0	264.25	-0.82	264.25	0.66
	12.1	262.11	-0.98	262.11	0.79
	8.7	260.19	-0.97	260.19	0.78
	5.6	258.46	-1.07	258.46	0.86
	2.7	256.89	-1.17	256.89	0.94
	0.1	255.44	-1.33	255.44	1.07
	-2.3	254.11	-1.41	254.11	1.13
	-4.5	252.87	-1.43	252.87	1.15
	-6.6	251.71	-1.52	251.71	1.22
	-8.5	250.63	-1.63	250.63	1.31
	-10.4	249.62	-1.73	249.62	1.39
	-12.2	248.58	-1.79	248.58	1.44
	-15.4	246.82	-1.93	246.82	1.55
	-18.3	245.23	-2.05	245.23	1.65
	-20.9	243.78	-2.22	243.78	1.78
	-23.3	242.44	-2.36	242.44	1.89
	-25.5	241.21	-2.58	241.21	2.07
	-27.5	240.07	-2.65	240.07	2.13
	-29.5	239.01	-2.75	239.01	2.21
	-31.3	238.00	-3.02	238.00	2.42

• down_long_hemisp_shaded2_max
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• down_long_hemisp_shaded1_max
• down_long_hemisp_shaded1_std
• down_long_hemisp_shaded2_std
• down_long_hemisp_shaded2_min
• down_long_hemisp_shaded1_min

TWP/GNDRAD/C3 - IRT malfunction

The internal IRT power supply failed (probably due to a lightning strike on 11/14) and was 
drawing excessive current on the data logger's DC system. The problem was corrected by 
replacing the instrument with a spare.

• Effective Surface (Skin) Temperature(sfc_ir_temp)
• sfc_ir_temp_std
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)

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_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_std

• inst_sky_ir_signal

TWP/GNDRAD/C3 - IRT power

The IRT failed to report after a planned power outage to add lightning protection modules 
to the AC power wiring. The problem was corrected when a loose power connection to the 
logger was found, rectified, and power restored to the logger.

• Effective Surface (Skin) Temperature(sfc_ir_temp)
• sfc_ir_temp_std
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)

TWP/SKYRAD/C3 - 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)

TWP/GNDRAD/C3 - 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.

• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)

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

• inst_direct_normal

• Raw data stream - documentation not supported

TWP/GNDRAD/C3 - Maintenance activities affected GNDRAD

While maintenance was performed on the SMET anenometer, the GNDRAD instruments were 
inverted. Disregard GNDRAD data during this time.

• inst_up_long_dome_resist
• inst_sfc_ir_signal
• inst_up_short_hemisp
• lat
• lon
• base_time
• time
• alt
• inst_up_long_hemisp_tp
• inst_up_long_case_resist
• time_offset

• net_min
• net_std
• up_long_hemisp_std
• time_offset
• external_voltage
• lat
• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)
• lon
• Effective Surface (Skin) Temperature(sfc_ir_temp)
• logger_temp
• base_time
• net
• sfc_ir_temp_std
• net_max
• alt
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Maxima(up_long_hemisp_max)
• up_short_hemisp_std
• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Maxima(up_short_hemisp_max)
• bit_data
• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Minima(up_short_hemisp_min)
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Minima(up_long_hemisp_min)
• internal_voltage
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• Radiation, shortwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_short_hemisp)