DQRID : D081222.2
Start DateStart TimeEnd DateEnd Time Data Quality Metric
12/14/2008045712/30/20080040Incorrect
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Subject:
TWP/SKYRAD/C3 - Direct normal instrument failure
DataStreams:twpskyrad60sC3.b1, twpskyrad20sC3.a0
Description:
The NIP instrument (short_direct_normal data stream) failed giving bad data during this 
time period.  The failure start time coincides with a reported DC power failure but no 
connection between the reported power failure and the failure of this instrument could be 
determined. 

Ops also reported the tracker clock running 2.9 minutes slow during maintenance on 12/22 
0300GMT (see CS-2008-0714).  Again, the slow clock is not suspect and did not appear to 
affect alignment.

Ops replaced the NIP instrument on 12/30 and short_direct_normal data resumed normal 
operation.

Disregard the short_direct_normal (NIP) data during this time period or calculate using 
the global and diffuse instruments and the following relationship:
short_direct_normal = ((down_short_hemisp - down_short_diffuse_hemisp))/cos(zenith angle)
Suggestions: 
Measurements:twpskyrad20sC3.a0:
  • inst_direct_normal
more
twpskyrad60sC3.b1:
  • short_direct_normal_std
  • short_direct_normal_min
  • short_direct_normal
  • short_direct_normal_max
more

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