SGP/SIRS/E31 - Intake fan failure

Beginning on 12/18/2013 approx. 01:30GMT the down_short_hemisp (PSP instrument) ventilator 
fan failed.  It was replaced on 1/13/2014 approx. 18GMT returning the down_short_hemisp 
measurement to normal operation.

During the specified time the downwelling shortwave data (down_short_hemisp) are suspect 
and not correctable.  Users are advised to use the derived down_short_hemisp available 
from the QCRAD VAP (BestEstimate_down_short_hemisp).  This is the usual recommended source 
for downwelling shortwave broadband irradiance.

Use QCRAD data

• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Standard
  Deviation(down_short_hemisp_std)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Minima(down_short_hemisp_min)
• Down-welling unshaded pyranometer voltage(down_short_hemisp)
• Downwelling shortwave hemispheric irradiance, pyranometer, maxima(down_short_hemisp_max)

• Instantaneous Downwelling Hemispheric Shortwave, Pyranometer Thermopile Voltage(inst_global)