DQRID : D100521.3
Start DateStart TimeEnd DateEnd Time Data Quality Metric
03/26/2010000005/04/20101935Incorrect
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Subject:
SGP/SIRS/E21 - Tracker failure
DataStreams:sgpsirsE21.b1, sgpsirs20sE21.a0
Description:
First apparent on 03/26, the short_direct_normal values were incorrect after approximately 
1700GMT each day. The tracker was found to have excessive clock drift and was reset by 
site ops on 05/04/2010 and returned to service at 1935GMT. The down_short_diffuse_hemisp 
values appear unaffected by the tracker misalignment.

The short_direct_normal data values are suspect after approximately 1800GMT each day from 
03/26 to 04/26 and after 1700GMT from 04/27 to the end of the period.  The 
short_direct_normal data are not recoverable but can be calculated indirectly using the following 
relationship for each minute of data:
down_short_hemsip = short_direct_normal * cos(zenith angle) + down_short_diffuse
Suggestions: 
Measurements:sgpsirs20sE21.a0:
  • inst_direct_normal
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sgpsirsE21.b1:
  • short_direct_normal
  • short_direct_normal_std
  • short_direct_normal_max
  • short_direct_normal_min
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