SGP/QCRAD/E21 - Tracker out of alignment

Tracker appears to be out of alignment or inoperative during these times. The 
short_direct_normal (NIP) and down_short_diffuse_hemisp (8-48) data appear to be bad and not 
recoverable.

Some of these dates are documented in instrument DQRs:

D030529.3, D030612.1, D030722.2, D040229.2, D080602.2, D080722.1

• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)

• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)

• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)

SGP/QCRAD/E21 - Reprocess: Incorrect PIR/UIR Calibration Coefficient

Problem documented in instrument DQR D031009.2:

Incorrect coefficients were applied to the upwelling longwave radiation
measurement instrument (i.e. pyrgeometer, SIRS acroynm "UIR") during
this time period.

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

2) For each one minute data entry in b1
     tpUIR[uV] = up_long_netir[uV]/0.2523876[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)
	    =[0.28902*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)
		
Other datastream corrections that use the UIR measurements will require
similar corrections.


See the following web site for additional information on the pyrgeometer
equations, specifically sections 2.1(Single Calibration Factor Approach)
and 2.2 (Four Coefficient Calibration Approach)

      http://www.arm.gov/docs/instruments/static/pyrg.html

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

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

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

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

SGP/QCRAD/E21 - Bird Poop Contamination

Documented in instrument DQR D031020.4.

Downwelling shortwave values were erratic during the day on 10/18 and in very poor 
agreement
at times with downwelling shortwave values calculated from direct and diffuse 
measurements.
Bi-weekly preventative maintenace records indicate bird poop was cleaned from the 
downwelling

indicate no bird contamination since 10/29.

Turkey vultures are the usual suspects in data quality problems at this facility. The

beginning in late October the birds had left the site.

• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)

• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)

• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)

• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)