SGP/SIRS/E34 - Ventilation fan failure

On June 1, 2013 the ventilator fan on the PSP (down_short_hemisp) instrument failed.  

This adversely affected the down_short_hemisp data during the specified period.  Data 
review indicates the daytime DS data appear unaffected during the problem period. However, 
the additional uncertainly in down_short_hemisp due to this failure is not quantifiable.

The down_short_hemisp from the b1 datastream should be avoided during this time period.  
The sgpqcrad1longE34 BestEstimate_down_short_hemisp remains the most accurate estimate of 
down_short_hemisp since it primarily uses the unaffected direct normal and diffuse 
measurements.

Use QCRAD data

• Downwelling shortwave hemispheric irradiance, pyranometer, maxima(down_short_hemisp_max)
• 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)

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