| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D030722.2 | SGP/SIRS/E21 - Shadowband Misalignment | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| D031009.2 | SGP/SIRS/E21 - Reprocess: Incorrect PIR/UIR Calibration Coefficient | sgpsirsE21.00, sgpsirsE21.b1 |
| D031020.4 | SGP/SIRS/E21 - Bird Poop Contamination | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| D040126.3 | SGP/SIRS/E21 - False signal | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| D040229.2 | SGP/SIRS/E21 - Shadowband Misalignment | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| D040329.1 | SGP/SIRS/E21 - Instrument logger time problem, Unknown | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| D040601.1 | SGP/SIRS/E21 - Dirt on dome | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| D060424.1 | SGP/SIRS/E21 - Roosting birds in field of view | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| D060630.27 | SGP/SIRS/E21 - Reprocessed: Longwave Calibration error | 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: | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| 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 |
|---|---|---|---|
| 10/18/2003 | 1600 | 10/29/2003 | 1630 |
| Subject: | SGP/SIRS/E21 - Bird Poop Contamination |
| DataStreams: | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| Description: | Downwelling shortwave values were erratic during the day on 10/18 and in very poor agreement at times with downwelling shortwave values calculated from direct and diffuse measurements. Bi-weekly preventative maintenace records indicate bird poop was cleaned from the downwelling shortwave instrument on 10/29 at 16:30. Review of maintenance records and instrument data indicate no bird contamination since 10/29. Turkey vultures are the usual suspects in data quality problems at this facility. The RBD(rotating bird deterrent) had failed the week of 10/13 and is awaiting parts. However, beginning in late October the birds had left the site. |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 10/19/2003 | 0000 | 02/26/2004 | 2359 |
| Subject: | SGP/SIRS/E21 - False signal |
| DataStreams: | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| Description: | During clear-sky conditions, downwelling shortwave values spike downward approximately 50 to 200 W/m^2 around 22:15 UTC for about 15 minutes. This problem occurs at about the same time for the same duration each day during the indicated period of the year. This effect is due to a shadow from the Rotating Bird Deterrent (RBD) installed earlier in the year to prevent extensive bird droppings at the site. The RBD is installed at such a location that it will partially shade the downwelling shortwave PSP from 19 October to 23 February of the year. |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/20/2004 | 1300 | 03/03/2004 | 1300 |
| Subject: | SGP/SIRS/E21 - Shadowband Misalignment |
| DataStreams: | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| Description: | The NIP reported values close to zero and downwelling shortwave global and diffuse were equivalent due to tracker failure. Maintenance replaced tracker 2/27, but couldn't replace instruments until 03/02 2000 GMT due to bird poop contamination. |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 03/21/2004 | 1200 | 03/24/2004 | 0200 |
| Subject: | SGP/SIRS/E21 - Instrument logger time problem, Unknown |
| DataStreams: | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| Description: | Values of diffuse hemispheric shortwave radiation differ from derived values by at most 70 Wm^(-2). The incident appears to be isolated to 3/21, 3/22, and 3/23. An estimation of solar noon using downwelling shortwave hemispheric irradiance from the PSP shows solar noon to oocur at around 1845GMT on 3/21. Calculated solar noon occurs at E21 at 1831GMT for 3/21/2004. There appears to be a time discrepancy in the datalogger for these dates. 04/01 is the next date with enough sun to determine solar noon and compare to calculated. The data from this date appears correct. Ronald Reed [rreed@ops.sgp.arm.gov] reports the logger did not receive any reportable time updates during the late March time period. We don't know what happened during these three dates but from 3/24 on data looks acceptable. |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 05/28/2004 | 1500 | 06/09/2004 | 1342 |
| Subject: | SGP/SIRS/E21 - Dirt on dome |
| DataStreams: | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| Description: | Measured downwelling shortwave values differed from calculated
(direct + diffuse) by +/-100 W/m^2 in the afternoon. Pattern of
differences is indicative of a dirty downwelling shortwave dome.
Maintenance on 6/9 cleaned water spots on the dome. Other
downwelling instruments may have also been dirty during this
period. |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 04/07/2006 | 1200 | 05/31/2006 | 1700 |
| Subject: | SGP/SIRS/E21 - Roosting birds in field of view |
| DataStreams: | sgpsirs20sE21.a0, sgpsirsE21.00, sgpsirsE21.b1 |
| Description: | The RBDD (Rotating Bird Deterrent Device) installed at E21 to prevent turkey vultures from roosting on the instrument boom failed resulting in noisy NIP (Short Direct Normal) and PSP (Short Global Hemispheric) data and a spike occurring around 2230 UTC everyday due to obstruction of the field of view. Problem is intermittant due to moving birds. Use data with discretion. Follow ARM (DQMS3) flag recommendations for QC flags 02 or 03 found in section 5.1.4 of the SIRS handbook: http://www.arm.gov/publications/tech_reports/handbooks/sirs_handbook.pdf |
| Measurements: | sgpsirsE21.00:
sgpsirs20sE21.a0:
sgpsirsE21.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/23/2003 | 1520 | 02/15/2006 | 1515 |
| Subject: | SGP/SIRS/E21 - Reprocessed: Longwave Calibration error |
| DataStreams: | sgpsirsE21.b1 |
| Description: | Modified pyrgeometer calibration procedures were implemented beginning in July 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 have been reprocessed to remove the calibration bias. The reprocessed 60 second averaged data are based on 3 instantaneous 20 second data records rather than on 60 1 second instantaneous data records. Still, these data are considered far superior to the originally processed data. The reprocessed data were archived in November 2006. |
| Measurements: | sgpsirsE21.b1:
|