SGP/SIRS/E21 - NIP and PSP shaded by RBDD

E21 Okmulgee has a RBDD (Rotating Bird Deterrent Device) installed on the instrument deck 
to deter birds during the summer months.  The RBDD support and rotating boom is installed 
at the NE and SW corners of the deck.  The SIRS instruments are briefly shaded by the 
RBDD.

The Global horizontal shortwave irradiance measurement, the PSP instrument, is mounted 
near the NE corner of the deck and is consequently shaded by the SW corner RBDD from 
approximately October 20th to Feb 15 of each year for several minutes varying from 2130 to 
2300GMT.  This is an azimuth angle from approximately 228 to 233 degress during this time period.

The Direct normal shortwave irradiance measurement, the NIP instrument, is mounted on the 
radiometer tracker at the SE corner of the deck.  The NIP is shaded by the SW corner RBDD 
during much of the year from approximately August 20th to April 20th from 2200 to 
2330GMT.  This encompasses an azimuth angle from 239 to 259 degrees.

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• Instantaneous direct normal shortwave irradiance, pyrheliometer thermopile
  voltage(inst_direct_normal)
• Instantaneous Downwelling Hemispheric Shortwave, Pyranometer Thermopile Voltage(inst_global)

• Down-welling unshaded pyranometer voltage(down_short_hemisp)
• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)
• 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)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Shortwave direct normal irradiance, pyrheliometer, minima(short_direct_normal_min)