SGP/SIRS/E16 - Direct normal instrument failure

The short_direct_normal/NIP data spiked a few times and then completely failed resulting 
in missing values (-9999) for this time period.  

The short_direct_normal data during this time period is not recoverable. However, it can 
be reconstructed using the following shortwave instrument relationship for each minute of 
data:

short_direct_normal = (down_short_hemisp - down_short_diffuse)/cos(zenith angle).

• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• short_direct_normal_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)

• inst_direct_normal

SGP/SIRS/E16 - Questionable downwelling SW hemisp

There was an abnormal difference between downwelling shortwave hemispheric data and 
derived downwelling shortwave hemispheric data 7/16 - 7/24 between ~16:00-20:00 GMT. 

Data review indicates that the derived downwelling shortwave hemispheric 
(down_short_hemisp) data and possibly the shortwave direct normal (short_direct_normal) data were slightly 
lower (up to 50W/m2) than usual at these times. Either the downwelling shortwave 
instrument dome or the short direct normal instrument window may have been dirty during this 
time.  The downwelling shortwave instrument (PSP) is most likely to blame.  After recorded 
precipitation on 7/24 and 7/25 the problem resolved.  Ops visit on 7/26 recorded no 
observable contamination.  The instrument mentors guesses that the precipitation event 
effectively cleaned the instruments.

No recurrence has been observed since 7/24.

• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• down_short_hemisp_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• short_direct_normal_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)

• inst_direct_normal
• inst_global

SGP/SIRS/E16 - NIP failure

After a data outage, all short_direct_normal data were reported as missing. Maintenace 
discovered a failed NIP instrument and replaced it on 9/23 1640GMT.

• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• short_direct_normal_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)

• inst_direct_normal

SGP/SIRS/E16 - Missing data due to cable damage

Starting 11/23 at 00:47 UTC, all upwelling shortwave hemispheric values are missing. 

Additionally, starting 12/9 at 06:01 UTC, all upwelling longwave hemispheric irradiance 
values are missing.

Site ops determined that the tower cable had been chewed through. Repaired the cable on 
12/14/2010 and returned to service at 18:48 GMT.

• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)
• Upwelling Longwave Hemispheric Net Infrared(up_long_netir)
• inst_up_long_case_temp
• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Minima(up_short_hemisp_min)
• up_short_hemisp_std
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Minima(up_long_hemisp_min)
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Maxima(up_long_hemisp_max)
• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Maxima(up_short_hemisp_max)
• inst_up_long_dome_temp
• up_long_hemisp_std
• Radiation, shortwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_short_hemisp)

• inst_up_long_dome_resist
• inst_up_short_hemisp
• inst_up_long_hemisp_tp
• inst_up_long_case_resist

SGP/SIRS/E16 - Downwelling global SW incorrect

The down_short_hemisp (PSP instrument) values exhibit a large offset due to ventilator fan 
failure and induced instrument heating.  This offset cannot be corrected.  

Users can derive an estimate of global shortwave values with the following formula:
global = direct * cos(zenith angle) + diffuse

• down_short_hemisp_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)

• inst_global