SGP/SIRS/C1 - NIP failure

The short_direct_normal (NIP instrument) cable failed during this time period.	Data are 
not recoverable.

Users can derive an estimate of direct normal values using the following formula:
short_direct_normal = (down_short_hemisp - down_short_diffuse_hemisp)/cos(zenith angle)

• inst_direct_normal

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• short_direct_normal_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)

SGP/BRS/C1 - SW Direct Normal incorrect

Apparent lightning strike in the instrument cluster area resulted in a failed NIP. Data 
are missing or incorrect.  

The SIRS was due for calibration change outs so the US, DS, DD and NIP were replaced. The 
updated program was loaded at approximately 06/14/2011 1739 GMT.

An estimate of direct normal values can be derived using the following formula:

short_direct_normal = (down_short_hemisp - down_short_diffuse_hemisp)/cos(zenith angle)

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• short_direct_normal_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)

• inst_direct_normal

SGP/BRS/C1 - Tracker failure

Apparent lightning strike in the instrument cluster area resulted in a failed tracker. 
Site ops found the suntracker at home position, power cycled the suntracker and replaced 
fuse.

• down_short_diffuse_hemisp_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)

• inst_diffuse

SGP/SIRS/C1 - NIP Failure

The short_direct_normal (NIP instrument) cable failed (broken wire in NIP connector) 
during this time period. Data are not recoverable.


An estimate of direct normal values can be derived using the following formula:

short_direct_normal = (down_short_hemisp - down_short_diffuse_hemisp)/cos(zenith angle)

• inst_direct_normal

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• short_direct_normal_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)

SGP/BRS/C1 - Reprocess: Incorrect calibration coefficient for down_short_diffuse_hemisp

Applied calibration coefficient and serial number for down_short_diffuse was incorrect for 
the specified period.

Perform the following calculation to correct the data, 
DD= downwelling diffuse instrument:
Old Calibration coefficient = 114.74[W/m2\mV]
New Calibration Coefficient = 109.51[W/m2\mV]   
DD(new)[W/m2]=( DD(old)[W/m2]/ 114.74 [W/m2\mV] )* 109.51 [W/m2/mV]

• down_short_diffuse_hemisp_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)

• inst_diffuse

SGP/SIRS/C1 - Reprocess: Incorrect downwelling longwave calibration coefficient

Calibration coefficient for downwelling longwave was incorrect for the specified period.

To correct the one minute data b1 datastream follow the procedure below:
1) Obtain the following variables from the 20s datastream for each one minute of the 
affected time range:
  inst_down_long_shaded_dome_resist (Rd)
  inst_down_long_shaded_case_resist (Rc)
  inst_down_long_hemisp_shaded_tp (tpDIR_mV)
                                         
2) using the 20s tp voltage in mV convert to uV.
  tpDIR[uV] = inst_down_long_hemisp_shaded_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=0.2762)
  WinDIR(W/m2)= [0.2762*tpDIR] + Sigma*Tc^4 -4*Sigma*(Td^4 - Tc^4)
  where, Sigma = 5.6704E-8 (Stefan-Boltzman Const)
                                      
5) Generate new 1 minute average from the 3 20-second measurements

• inst_down_long_shaded_dome_resist
• inst_down_long_shaded_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded_tp)

• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• down_long_hemisp_shaded_std
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Downwelling Longwave Hemispheric Net Infrared(down_long_netir)
• inst_down_long_shaded_case_temp
• Downwelling Longwave Hemispheric Irradiance, Shaded Ventilated Pyrgeometer(down_long_hemisp_shaded)
• inst_down_long_shaded_dome_temp