SGP/SIRS/E11 - Ventilator Fan Failure

Beginning on 12/23/2013 approx. 16:00GMT the down_short_hemisp (PSP instrument) ventilator 
fan failed. Site Ops repaired the ventilator and returned the instrument to service on 
1/7/2014.

The down_short_hemisp data are not recoverable during this time range.  However, users can 
reconstruct the data using the following relationship between the down_short_hemisp and 
the short_direct_normal and short_diffuse_hemisp data for each one minute measurement:

down_short_hemisp = short_direct_normal * cos(zenith angle) + short_diffuse_hemisp

Problem should not adversely affect any overlying VAPs such as the QCRAD that will use 
this relationship as determined by QC flags.

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

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