| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D030529.3 | SGP/SIRS/E21 - Shadowband Misalignment/Tracker Failure | sgpsirsE21.00, sgpsirsE21.b1, sgpsirs20sE21.a0 |
| D030612.1 | SGP/SIRS/E21 - Shadowband Misalignment/Tracker Failure | sgpsirsE21.00, sgpsirsE21.b1, sgpsirs20sE21.a0 |
| D030722.2 | SGP/SIRS/E21 - Shadowband Misalignment | sgpsirsE21.00, sgpsirsE21.b1, sgpsirs20sE21.a0 |
| D031009.2 | SGP/SIRS/E21 - Reprocess: Incorrect PIR/UIR Calibration Coefficient | sgpsirsE21.00, sgpsirsE21.b1 |
| D060630.27 | SGP/SIRS/E21 - Reprocess: Longwave Calibration error | sgpsirsE21.b1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 05/19/2003 | 1000 | 05/28/2003 | 1430 |
| Subject: | SGP/SIRS/E21 - Shadowband Misalignment/Tracker Failure |
| DataStreams: | sgpsirsE21.00, sgpsirsE21.b1, sgpsirs20sE21.a0 |
| Description: | The solar tracker failed beginning around sunrise on 05/19/03 most likely during the previous nights reset. Failure time was approximate time of sunrise at 1000 on 05/19/03. The tracker was power cycled and RTS at 1415 GMT on 05/28/03. |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/03/2003 | 1000 | 06/16/2003 | 1835 |
| Subject: | SGP/SIRS/E21 - Shadowband Misalignment/Tracker Failure |
| DataStreams: | sgpsirsE21.00, sgpsirsE21.b1, sgpsirs20sE21.a0 |
| Description: | Suntracker appears to have failed beginning on 6/3/03, most likely during previous night reset. Start time listed is approximate time of sunrise. |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/17/2003 | 1000 | 08/06/2003 | 1350 |
| Subject: | SGP/SIRS/E21 - Shadowband Misalignment |
| DataStreams: | sgpsirsE21.00, sgpsirsE21.b1, sgpsirs20sE21.a0 |
| Description: | Solar tracker stopped functioning on 7/17. Tracker power cycled on
07/24 and returned to normal tracking but failed again 7/25. Power
was cycled again 8/6 and tracker performance was sustained thereafter. |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/23/2003 | 1330 | 08/08/2003 | 1650 |
| Subject: | SGP/SIRS/E21 - Reprocess: Incorrect PIR/UIR Calibration Coefficient |
| DataStreams: | sgpsirsE21.00, sgpsirsE21.b1 |
| Description: | Incorrect coefficients were applied to the upwelling longwave radiation
measurement instrument (i.e. pyrgeometer, SIRS acroynm "UIR") during
this time period.
For a PIR mounted in an upwelling measurement orientation (UIR), the
thermopile output is extremely low compared to a downwelling PIR (DIR).
In addition, the UIR case and dome temperature differences are much
smaller than a DIR. This results in the pyrgeometer receiver radiation
term, Wr (NREL/Hickey equation) or Wc (Albrecht/Cox equation), dominating
all other terms of the infrared radiant flux equation.
Since the receiver radiation term uses coefficients in both forms of
the pyrgeometer equations nearly equal to 1.0 +- <1% the result is a
measurement of incoming longwave radiant flux relatively insensitive
to the installed instrument - so long as it is an Eppley PIR.
Evaluation of the problem data shows the expected error of the data
(before correction) will be within 1% - less than the uncertainty of
the instrument (Eppley PIR greater of 5% or 5 W/m2)
To correct the one minute data found in the a1 or b1 datastream follow
this procedure:
1) Obtain the following variables from the b1 datafile:
inst_up_long_dome_temp
inst_up_long_case_temp
up_long_netir
2) For each one minute data entry in b1
tpUIR[uV] = up_long_netir[uV]/0.2523876[W/m2/uV]
3) Apply for each one minute data entry:
WinUIR(W/m2)=k*V+ Sigma*Tc^4 -4*Sigma*(Td^4 - Tc^4)
=[0.28902*tpUIR]+[Sigma*inst_up_long_case_temp^4]
-[4*Sigma*(inst_up_long_dome_temp^4-inst_up_long_case^4)]
where, Sigma = 5.6697E-8 (Stefan-Boltzman Const)
Other datastream corrections that use the UIR measurements will require
similar corrections.
See the following web site for additional information on the pyrgeometer
equations, specifically sections 2.1(Single Calibration Factor Approach)
and 2.2 (Four Coefficient Calibration Approach)
http://www.arm.gov/docs/instruments/static/pyrg.html |
| Measurements: | sgpsirsE21.00:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/23/2003 | 1520 | 02/15/2006 | 1515 |
| Subject: | SGP/SIRS/E21 - Reprocess: Longwave Calibration error |
| DataStreams: | sgpsirsE21.b1 |
| Description: | Modified pyrgeometer calibration procedures were implemented beginning in December 2003.
These modified procedures introduced a calibration bias in the longwave data. The
previous procedures were re-implemented at all sites between December 2005 and February 2006 to
restore proper calibrations.
The data collected while the incorrect procedures were in place are
being reprocessing to remove the calibration bias. Note, this also affected standard
deviation, maximum and minimum data fields. |
| Measurements: | sgpsirsE21.b1:
|