TWP/SKYRAD/C2 - Reprocess: Incorrect UVB Calibration Coefficient

The uvb calibration coefficient was entered incorrectly as 0.2151
instead of 0.2332.

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

TWP/SKYRAD/C2 - 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.

• uvb_min
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• down_uvb_std
• uvb_max
• uvb_sd
• uvb_mean
• Irradiance, ultraviolet, downwelling, UV Biometer, mifkba(down_uvb_min)
• Irradiance, ultraviolet, downwelling, UV Biometer(down_uvb)

TWP/SKYRAD/C2  - Reprocessed and Corrected: IRT incorrect min/delta values

DATA REPROCESSED and CORRECTED: 

The min/max/delta values for sky_ir_temp were originally incorrect in the 60s files
(xxxskyrad60sFn.b1).
TWP was -49.7/40/-9999 and NSA was -49/50/50.
The min/max/delta for the TWP and NSA data has now been corrected to -60/40/50.

The data were archived in November 2016. Please retrieve the reprocessed data for use in 
your
analysis.

You may find these data using the ARM Discovery tool at the following link:
http://www.archive.arm.gov/discovery/#v/results/s/finst::skyrad/fsite::nsa/ffac::nsa.C1
http://www.archive.arm.gov/discovery/#v/results/s/finst::skyrad/fsite::nsa/ffac::nsa.C2
http://www.archive.arm.gov/discovery/#v/results/s/finst::skyrad/fsite::twp/ffac::twp.C1
http://www.archive.arm.gov/discovery/#v/results/s/finst::skyrad/fsite::twp/ffac::twp.C2
http://www.archive.arm.gov/discovery/#v/results/s/finst::skyrad/fsite::twp/ffac::twp.C3


ORIGINAL DQR CATEGORY: Transparent (Does not affect quality )

REPROCESSED and CORRECTED DATA ARCHIVED:2016-11

REPROCESS IDENTIFICATION NUMBER: RID 119

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--- ORIGINAL DQR DESCRIPTION ---
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For field sky_ir_temp, the value of valid_min was incorrectly assigned to -49.7 C and no 
value of valid_delta was assigned. The actual values should be -60 and 50 C, respectively.

• Sky infrared temperature(sky_ir_temp)
• sky_ir_temp_max
• sky_ir_temp_min

TWP/SKYRAD/C2 - Incorrect Calibration Coefficients Applied

Incorrect calibration coefficients were entered for three instruments (PSPG, PIRD and 
PIRG) at the RESET period.

The following calculation method should be applied to correct the data, 

For the downwelling shortwave(PSPG) (DS)
Old Calibration coefficient [W/m2\mV] =119.68
New Calibration Coefficient [W/m2\mV] =125.94
DS(new_value)[W/m2]=( DS(old_value)[W/m2]/ 119.68 [W/m2\mV] )* 125.94 [W/m2/mV]

For the longwave irradiance (PIRG):

If the .a0 and .b1 data set available the following procedure should be applied for the 
downwelling LW
1) Obtain the following variables from the 20s datastream for each one minute of the 
affected time range:
  inst_down_long_hemisp1_dome_resist (Rd)
  inst_down_long_ hemisp1_case_resist (Rc)
  inst_down_long_ hemisp1_tp (tpDIR_mV)
					 
2) Using the 20s tp voltage in mV convert to uV.
  tpDIR[uV] = inst_down_long_hemisp1_tp [mV]*1000[uV/mV]

3) For each 20s data entry, convert Rd and Rc to temperature
  Td =1/ (a0 + (a1*LN (Rd*1000) + (a2*LN (Rd*1000)^3)))
  Tc = 1/ (a0 + (a1*LN (Rc*1000) + (a2*LN (Rc*1000)^3)))
  Where a0 = 0.0010295 
	a1 = 0.0002391
	a2 = 0.0000001568

4) Apply for each 20s data entry: (correct k1=0.2755)
  WinDIR(W/m^2)= [0.2755*tpDIR] + Sigma*Tc^4 -4*Sigma*(Td^4 - Tc^4)
  Where, 
	WinDIR = Corrected down_long_hemisp1 (W/m^2)
	Sigma = 5.6704E-8 (Stefan-Boltzman Constant)

				      
5) Generate new 1 minute average from the three 20-second measurements

For the longwave irradiance (PIRD):

If the .a0 and .b1 data set available the following procedure should be applied for the 
downwelling LW
1) Obtain the following variables from the 20s datastream for each one minute of the 
affected time range:
  inst_down_long_hemisp2_dome_resist (Rd)
  inst_down_long_ hemisp2_case_resist (Rc)
  inst_down_long_ hemisp2_tp (tpDIR_mV)
					 
2) Using the 20s tp voltage in mV convert to uV.
  tpDIR[uV] = inst_down_long_hemisp2_tp [mV]*1000[uV/mV]

3) For each 20s data entry, convert Rd and Rc to temperature
  Td =1/ (a0 + (a1*LN (Rd*1000) + (a2*LN (Rd*1000)^3)))
  Tc = 1/ (a0 + (a1*LN (Rc*1000) + (a2*LN (Rc*1000)^3)))
  Where a0 = 0.0010295 
	a1 = 0.0002391
	a2 = 0.0000001568

4) Apply for each 20s data entry: (correct k1=0.2786)
  WinDIR(W/m^2)= [0.2786*tpDIR] + Sigma*Tc^4 -4*Sigma*(Td^4 - Tc^4)
  Where, 
	WinDIR = Corrected down_long_hemisp2(W/m^2)
	Sigma = 5.6704E-8 (Stefan-Boltzman Constant)

				      
5) Generate new 1 minute average from the three 20-second measurements

• inst_down_long_hemisp2_case_temp
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• Downwelling shortwave hemispheric irradiance, pyranometer(down_short_hemisp)
• down_long_hemisp1_std
• down_long_hemisp1_min
• inst_down_long_hemisp1_dome_temp
• inst_down_long_hemisp2_tp
• down_long_hemisp2_max
• down_long_hemisp1_max
• down_long_hemisp2_min
• inst_down_long_hemisp1_tp
• down_long_hemisp2_std
• inst_down_long_hemisp2_dome_temp
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• Irradiance, shortwave, downwelling, hemispheric, pyranometer, mifkba(down_short_hemisp_min)
• down_short_hemisp_std
• inst_down_long_hemisp1_case_temp

TWP/SKYRAD/C2 - 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, Maxima(down_uvb_max)
• down_uvb_std
• Irradiance, ultraviolet, downwelling, UV Biometer, mifkba(down_uvb_min)
• Irradiance, ultraviolet, downwelling, UV Biometer(down_uvb)

TWP/SKYRAD/C2 - IRT bias

Measurements of sky temperature, especially those <250K, were positively biased compared 
with AERI because there was no compensation for the reflectivity of the gold mirror. The 
problem was corrected by changing the IRT emissivity from 1.000 to 0.987.

Use sky temperature measurements less than 230K with caution. Biases as large as 30K have 
been observed when the actual temperature, as measured by AERI, is less than 210 K.

• Sky infrared temperature(sky_ir_temp)
• sky_ir_temp_max
• sky_ir_temp_min