SGP/SIRS/E8 - Possible Contamination of DS PSP instrument

Downwelling hemispheric shortwave values drop at about 1500 GMT under clear sky 
conditions, typically from about 14:00GMT to 16:00GMT.  This may be due to a dirty PSP but 
maintenance on 03/23/04 18:11 GMT revealed no more than typical light dust.  The problem was 
essentially undetectable by  03/31/04 12:00. The time of day that the problem exists appears 
to be an exagerated PSP cosine response.  No obvious reason presents why the problem 
appeared and then disappeared within this two week period.

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• 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)

• (Raw data stream - documentation not supported)

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