DQRID : D960602.3
Start DateStart TimeEnd DateEnd Time Data Quality Metric
01/06/1994000012/06/19941313Suspect
more
Subject:
Level of pyranometer for global solar was slightly off
DataStreams:sgpsirosE13.a1
Description:
DQR No:                               Platform: sgpsiros13

Subject: Level of pyranometer for global solar was slightly off

Date Submitted:  6/1/96
Submitted By: Marv Wesely             ___  Instrument Mentor
                                      ___  EST Member
                                      ___  Science Team Member
                                      _x_  Other __IT leader__
 
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at dqr@arm.gov.

Platform/Measurement:
    What level data: (raw,a0,a1,b1,c1 etc):
    All levels of sgpsiros13, but only for down_short_hemisp.

    What location was the data collected at: 
 
    Period of time in question
        Begin Date  01/06/94
        End Date    12/06/94   Time   06:00    (GMT)

 Data should be labeled:
 ___  questionable                      ___  All data fields affected
 ___  incorrect                         _x_  Only some data fields affected
 ___  wrong calibration
 _x_  others 
 
 Discussion of Problem:

Analysis of SIROS data from the central facility has indicated 
that the pyranometer (or PSP) used for global (solar) irradiance 
observations appeared to be slightly off level until site operations 
personnel re-leveled the sensor on Dec. 6, 1994.  Calculations suggest 
that the sensor was leaning roughly toward the east by about 1.2 degrees.  
Comparisons to the nearby BSRN pyranometer ("psp2") show that the 
SIROS sensor was reading to high in the morning by as much as 5% and
too small in the late afternoon by about the same percentage.  
Little, if any, effect was seen between 1700 and 2100 UTC (in 
November), and the effect was be practically zero under cloudy
skies.  

Users of the data could conceivable adjust the data (down_short_hemisp
for sgpsiros13) with the direct-beam SIROS or BSRN observation and
values of the solar zenith and azimuth angles, which would need to 
be computed, and some fairly straighforward geometry calculations.
Possibly an easier course of action is to rely on the BSRN observation 
of global solar radiation for small solar elevation angles.

(This analysis was conducted by John DeLuisi and colleagues
in 1994 but was not documented with a DQR.  Some recent
discussions I have had with Science Team members have indicated
that they have seen this problem also.)

Other observations/measurements impacted by this problem:

None.

Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)

Ideally, this note would be sent Send to people who received SIROS13 
data for dates before Dec. 6, 1994, and the appropriate data in the 
archive would be flagged with this comment.
Suggestions: 
Measurements:sgpsirosE13.a1:
  • alt
  • hemisp_narrowband
  • flag_nighttime1-24
  • down_long_diffuse_hemisp
  • mfrsr_temp
  • up_short_hemisp
  • time_offset
  • down_long_case_temp
  • logger_temp
  • down_short_diffuse_hemisp
  • flag_zero_divisor1-24
  • lon
  • channel
  • base_time
  • up_long_hemisp
  • up_long_dome_temp
  • direct_norm_broadband
  • up_long_case_temp
  • diffuse_hemisp_broadband
  • flag_ln_error1-24
  • therm_volt
  • short_direct_normal
  • down_long_dome_temp
  • lat
  • hemisp_broadband
  • direct_norm_narrowband
  • diffuse_hemisp_narrowband
  • logger_volt
  • down_short_hemisp
  • flag_zero_cosine1-24
more

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