SGP/SIRS/E18 - Possible PSP dome contamination

Downwelling shortwave hemispheric (DSH) measurements did not agree with derived DSH 
readings during the morning hours up to 1500GMT each clear day.   PM cleaning on 2/16 2250 
revealed nothing other than dirty water spots.  A dirty or ice covered PSP dome may have been 
the cause, clearing itself before the PM crew arrived.

Data during clear skies between 0000-1500GMT are suspect.

• 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, maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Minima(down_short_hemisp_min)

• (Raw data stream - documentation not supported)