SGP/SIRS/E16 - PSP Dome Contamination

Downwelling Shortwave (DS) values near 22:00 GMT during clear skys are
lower than expected due to contamination of pyranometer dome.  A dime-sized
spot of dirt was found on the southwest portion of the pyranometer dome. 
DS values for cloudy conditions during this period are also suspect, but
the amount of irradiance reduction are not significant.

• inst_global

• down_short_hemisp
• down_short_hemisp_min
• down_short_hemisp_std
• down_short_hemisp_max