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/SKYRAD/C3 - UVB Data questionable/incorrect due to uncontrolled sensor temperature

The UVB was not temperature controlled to 25C as required
to ensure accurate data.  UVB data should ONLY be used after 
checking both the bit_data and twpskyrad20sC1.a1 uvb_temp
or inst_down_uvb_temp.  UVB data where the UVB temperature
was outside the range of 24-26C should not be used.

• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• down_uvb_std
• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)

• inst_down_uvb_temp
• Irradiance, ultraviolet, downwelling (UV Biometer)(inst_down_uvb_irradiance)

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, 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

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, 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

• Raw data stream - documentation not supported

TWP/GNDRAD/C3 - IRT bias

The IRT measured higher surface temperatures than expected from the PIR, even at night.

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

TWP/GNDRAD/C3 - Reprocess: IRT with wrong calibration

A spare IRT was installed that was not configured properly.

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

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/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)