DQRID : D051202.5
Start DateStart TimeEnd DateEnd Time Data Quality Metric
08/02/2004020009/09/20052022Incorrect
more
Subject:
TWP/SKYRAD/C1 - Reprocess: Incorrect datalogger program affecting PIR1 and PIR2 
downwelling longwave
DataStreams:twpskyrad20sC1.a0, twpskyrad60sC1.b1
Description:
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 absolute value of the errors are inversely proportial to temperature.

Users can apply temperature dependent irradiance corrections 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
Suggestions: 
Apply suggested corrections
Measurements:twpskyrad60sC1.b1:
  • down_long_hemisp_shaded1_min
  • down_long_hemisp_shaded2_min
  • down_long_hemisp_shaded1_max
  • down_long_hemisp_shaded1_std
  • down_long_hemisp_shaded2_max
  • down_long_hemisp_shaded2_std
  • down_long_hemisp_shaded1
  • down_long_hemisp_shaded2
more
twpskyrad20sC1.a0:
  • inst_down_long_shaded2_case_resist
  • inst_down_long_shaded2_dome_resist
  • inst_down_long_shaded1_dome_resist
  • inst_down_long_shaded1_case_resist
  • inst_down_long_hemisp_shaded1_tp
  • inst_down_long_hemisp_shaded2_tp
more

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