NSA/GNDRAD/C1 - Incorrect calibration coefficients

BarrowC1, Gndrad. On Aug 11th the PSP-US was changed out and the Campbell program was 
changed to reflect this.  However, an old program that uses the 4 coefficient PIR cal factors 
was used. The PIR-UIR was not changed out, however, the logger program coeffs reverted 
back to the 4 Coeffcients.  The Eppley PIR-UIR coefficients for this S/N 30168F3 are :  
K0=0.0, K1(aka k)=.25253, K2= 1.0, K3=-4, Kr=0.0.

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For a PIR mounted in an upwelling measurement orientation (UIR), the
thermopile output is extremely low compared to a downwelling PIR (DIR).
In addition, the UIR case and dome temperature differences are much
smaller than a DIR.  This results in the pyrgeometer receiver radiation 
term, Wr (NREL/Hickey equation) or Wc (Albrecht/Cox equation), dominating
all other terms of the infrared radiant flux equation.

Since the receiver radiation term uses coefficients in both forms of
the pyrgeometer equations nearly equal to 1.0 +- <1% the result is a
measurement of incoming longwave radiant flux relatively insensitive 
to the installed instrument - so long as it is an Eppley PIR.
		
Evaluation of the problem data shows the expected error of the data
(before correction) will be within 1% - less than the uncertainty of 
the instrument (Eppley PIR greater of 5% or 5 W/m2)
		
To correct the one minute data found in the a1 or b1 datastream follow
this procedure:
1) Obtain the following variables from the b1 datafile:
	 inst_up_long_dome_temp
	 inst_up_long_case_temp
	 up_long_netir


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     tpUIR[uV] = up_long_netir[uV]/0.2582[W/m2/uV]

3) Apply for each one minute data entry:

WinUIR(W/m2)=k*V+ Sigma*Tc^4 -4*Sigma*(Td^4 - Tc^4)
	    =[0.25253*tpUIR]+[Sigma*inst_up_long_case_temp^4]
	      -[4*Sigma*(inst_up_long_dome_temp^4-inst_up_long_case^4)]

where, Sigma =	5.6697E-8 (Stefan-Boltzman Const)
		

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For additional information see:
http://www.arm.gov/publications/tech_reports/arm-05-111.pdf

• Upwelling Longwave Hemispheric Irradiance, Pyrgeometer, Minima(up_long_hemisp_min)
• Net Radiation, Standard Deviation(net_std)
• PIR1 minimum(pir1_min)
• NET standard deviation(net_sd)
• 10 meter Upwelling Longwave Hemispheric Irradiance, Pyrgeometer(up_long_hemisp)
• NET mean(net_mean)
• PIR1 mean(pir1_mean)
• NET minimum(net_min)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Standard Deviation(up_long_hemisp_std)
• Upwelling longwave hemispheric irradiance, pyrgeometer, maxima(up_long_hemisp_max)
• PIR1 unshaded maximum(pir1_max)
• PIR1 unshaded standard deviation(pir1_sd)
• Net Radiation, Maxima(net_max)

• (Raw data stream - documentation not supported)

• Instantaneous PIR1 uncorrected irradiance(pir1_voltage)
• Instantaneous PIR1 dome thermistor(pir1_dome_therm)
• Instantaneous Upwelling Pyrgeometer Case Thermistor Resistance, Pyrgeometer(inst_up_long_case_resist)
• Instantaneous Upwelling Pyrgeometer Thermopile Pyrgeometer(inst_up_long_hemisp_tp)
• Instantaneous PIR1 case thermistor(pir1_case_therm)
• Instantaneous Upwelling Pyrgeometer Dome Thermistor Resistance Pyrgeometer(inst_up_long_dome_resist)

• Instantaneous Upwelling Pyrgeometer Case Thermistor Resistance, Pyrgeometer(inst_up_long_case_resist)
• Instantaneous Upwelling Pyrgeometer Dome Thermistor Resistance Pyrgeometer(inst_up_long_dome_resist)
• Instantaneous Upwelling Pyrgeometer Thermopile Pyrgeometer(inst_up_long_hemisp_tp)