DQR ID | Subject | Data Streams Affected |
---|---|---|
D960701.3 | Obstruction in the AERI-01 Enclosure | sgpaeri01ch1C1.a1, sgpaeri01ch2C1.a1, sgpaerilbldiffC1.c1, sgpaeri01summaryC1.a1, sgpaerilblcloudsC1.c1, sgpaerilbldifflsC1.c1, sgpaeri01engineerC1.a1 |
D960715.2 | Dust on the Scene Mirror | sgpaeri01ch1C1.a1 |
D990920.1 | SGP/AERI/C1 - Reprocessed: radiance data | sgpaeri01C1.00, sgplblch1C1.c1, sgplblch2C1.c1, sgpaeriprofC1.c1, sgplblch1lsC1.c1, sgplblch2lsC1.c1, sgpaeri01ch1C1.a1, sgpaeri01ch2C1.a1, sgpqmeaerilblC1.c1, sgpaerilbldiffC1.c1, sgpqmeaerilbllsC1.c1, sgpqmeaerimeansC1.c1, sgpaeri01summaryC1.a1, sgpaerilbldifflsC1.c1 |
Start Date | Start Time | End Date | End Time |
---|---|---|---|
05/21/1996 | 2200 | 06/13/1996 | 2200 |
Subject: | Obstruction in the AERI-01 Enclosure |
DataStreams: | sgpaeri01ch1C1.a1, sgpaeri01ch2C1.a1, sgpaerilbldiffC1.c1, sgpaeri01summaryC1.a1, sgpaerilblcloudsC1.c1, sgpaerilbldifflsC1.c1, sgpaeri01engineerC1.a1 |
Description: | DQR No: Subject: Obstruction in the AERI-01 Enclosure Date Submitted: Submitted By: Robert Knuteson ___ Instrument Mentor ___ EST Member _X_ Science Team Member ___ Other _____________________________ Organization: University of Wisconsin - Madison Email address: robert.knuteson@ssec.wisc.edu Telephone: 608-263-7974 Platform/Measurement: What level data: (raw,a0,a1,b1,c1 etc): All levels What location was the data collected at: ARM SGP CF Period of time in question Begin Date May/ 21/ 1996 Time 22:00 (GMT) End Date June/ 13/ 1996 Time 22:00 (GMT) Data should be labeled: ___ questionable _X_ incorrect ___ wrong calibration ___ others _______________________________ Discussion of Problem: The AERI Profile QME (Wayne Feltz) first detected a problem with AERI-01 data from the SGP CF. Investigation by site personnel on June 14, found numerous bird droppings in the area around the AERI-01 sky hatch plus some grass lying across a portion of the hatch opening. Using the AERI-LBLRTM QME to analyse the data after the fact it appears likely that nesting birds placed pieces of grass in a position to obstruct the AERI field of view to the sky. By some quirk of fate, the problem actually fixed itself about 12 hours before the site personnel made their inspection of the AERI viewport and discovered the evidence described above. The system has been operating normally since June 13, 1996 22:00 UTC as confirmed by a recent analysis of the AERI-LBLRTM QME results. Other observations/measurements impacted by this problem: This effects all QMEs and other analyses that use the AERI-01 data. Suggested Corrections of the Problem: (e.g. change calibration factor and recompute, flag data with this comment, etc.) It is unlikely that this data can or will be corrected. REQUIRED ACTIONS: This report is informational no further action required____X_____ Experiment Center action required as follows: None Site Operations action required as follows: None Archive action required as follows: None |
Measurements: | sgpaerilbldiffC1.c1:
sgpaeri01ch1C1.a1:
sgpaeri01summaryC1.a1:
sgpaeri01ch2C1.a1:
sgpaerilbldifflsC1.c1:
sgpaeri01engineerC1.a1:
sgpaerilblcloudsC1.c1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
01/18/1996 | 0000 | 04/09/1996 | 0000 |
Subject: | Dust on the Scene Mirror |
DataStreams: | sgpaeri01ch1C1.a1 |
Description: | DQR No: Subject: Dust on the AERI-01 Scene Mirror Date Submitted: Submitted By: Robert Knuteson ___ Instrument Mentor ___ EST Member _X_ Science Team Member ___ Other _____________________________ Organization: University of Wisconsin - Madison Email address: robert.knuteson@ssec.wisc.edu Telephone: 608-263-7974 Platform/Measurement: What level data: (raw,a0,a1,b1,c1 etc): All levels including the following platforms: sgpaeri01ch1C1.a1 sgpaeri01ch2C1.a1 sgpaeri01summaryC1.a1 sgpaeri01engineerC1.a1 What location was the data collected at: ARM SGP CF Period(s) of time in question Period 1: Begin Date Sep/ 1/ 1995 Time 00:00 (GMT) End Date Dec/ 22/ 1995 Time 00:00 (GMT) Period 2: Begin Date Jan/ 18/ 1996 Time 00:00 (GMT) End Date Apr/ 9/ 1996 Time 00:00 (GMT) Data should be labeled: _X_ questionable ___ incorrect ___ wrong calibration ___ others _______________________________ Discussion of Problem: On April 25, 1995 the AERI-01 was installed in an enclosure protruding out the side of the optical trailer at the ARM SGP central facility. This configuration was a change from the AERI prototype setup which used a roof hatch and a "chimney". The reason for the new configuration was to place the AERI front end (scene mirrors and blackbodies) in an environment that was much closer in temperature to the outside ambient air. In that regard the change has been very successful. Unfortunately this configuration also exposes the AERI scene mirror to contamination by airborne dust. At the time of installation only a rough opening to the sky existed with a wooden hatch that was manually removed and replaced by site personnel during normal working hours. Most of the time the hatch remained closed. When the automatic hatch for the AERI-01 system in the ARM SGP CF optical trailer was installed in July 1995, the percentage of time which the hatch was open increased dramatically. Since that time there has been a slow accumulation of dust on the AERI-01 scene mirror. No routine maintenance (such as mirror cleaning) was defined since this dust was thought to be only a thoughput problem but not a calibration issue. However, analysis of the AERI/LBLRTM QME (comparison of observed radiances to model calculations) indicated that there was a problem with the AERI-01 observations during the October 1995 ARESE IOP. On Dec 20, 1995 personnel from UW-Madison visited the site and determined that the dust on the scene mirror was acting as a scattering surface which effectively broadened the conical field of view to the blackbodies and the sky. This "broadening" of the field of view would not have lead to a problem except for the fact that hatch opening is too small at it's current distance from the instrument to allow the full beam to exit the enclosure. Thus a fraction of the AERI field of view (the "tail" of the field) was viewing the ambient temperature area surrounding the hatch opening. This caused a mixture of ambient temperature emission into the scene, a fact that is readily apparent when the scene was of a clear, dry sky (such as in the ARESE IOP). Period 1 indicated above covers the period from the first of September 1995 when this effect began to be noticeable to December 22, 1995 after the scene mirror had been cleaned of dust contamination by UW-Madison personnel. In general the scattering effect is increasing with time as more and more dust accumulates on the scene mirror, but does show "events" linked to times when the automatic hatch does not close soon enough and rain drops fall on the scene mirror. These rain drops seem have the effect of both making the scattering surfaces more effective (thus worse) and at other times of actually partially cleaning the mirror if the rain is heavy enough. Period 2, unfortunately only 4 weeks later, began with a different type of "event" but leading to the same effect. On Jan 18, 1996 a major winter storm caused snow to accumulate on the AERI-01 scene mirror (another example when the automatic hatch did not work properly). When the snow melted it appears to have left a substantial residue on the scene mirror leading to an abrupt increase in the scattered energy contribution as described above. This "dirty" mirror condition persisted until UW-Madison personnel replaced the scene mirror on April 8, 1996. Since April 1996, the AERI-01 system has been operating in the previous manner; thus one can expect that the scene mirror has been accumulating dust up to the present time. To address this recurring problem, UW-Madison is developing a procedure that would allow the AERI-01 scene mirror to be cleaned by site personnel on a regular basis. In addition, automatic diagnostic information has been developed to identify this problem immediately and provide feedback to site (and post analysis) personnel. Furthermore, modifications of the AERI enclosure design are under investigation that should build in an immunity to this effect at all future AERI installations. Other observations/measurements impacted by this problem: This affects QMEs and other analyses that use the AERI-01 data that require absolute accuracy better than about 5%. Suggested Corrections of the Problem: (e.g. change calibration factor and recompute, flag data with this comment, etc.) It is likely that this data can and will be corrected. The best approach to use in the correction is currently under investigation. REQUIRED ACTIONS: This report is informational no further action required_________ Experiment Center action required as follows: Distribution of a DQR to users of AERI data is recommended for the time periods described. Site Operations action required as follows: A schedule of cleaning for the central facility AERI scene mirror is recommended. A procedure for this task should be obtained from Fred Best of the University of Wisconsin - Madison combined with a training session on proper techniques. Archive action required as follows: None |
Measurements: | sgpaeri01ch1C1.a1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
10/01/1996 | 0000 | 06/30/1997 | 2359 |
Subject: | SGP/AERI/C1 - Reprocessed: radiance data |
DataStreams: | sgpaeri01C1.00, sgplblch1C1.c1, sgplblch2C1.c1, sgpaeriprofC1.c1, sgplblch1lsC1.c1, sgplblch2lsC1.c1, sgpaeri01ch1C1.a1, sgpaeri01ch2C1.a1, sgpqmeaerilblC1.c1, sgpaerilbldiffC1.c1, sgpqmeaerilbllsC1.c1, sgpqmeaerimeansC1.c1, sgpaeri01summaryC1.a1, sgpaerilbldifflsC1.c1 |
Description: | Due to a software error in the real-time calibration software, the AERI-01 radiance data between 10/96 and 6/97 were incorrectly calibrated. All of the AERI-01 radiance data collected at the SGP central facility during this time period was corrupted by this software error and were reprocessed to correct the radiance data. The error also affected all derived products of the AERI radiance data. AERI data collected prior to and after this time period was unaffected by this programming error. The proper calibrated radiance spectra was recovered from the raw archived dataset through post-processing. This reprocessing of the AERI data was carried out by the instrument mentor at PNNL and confirmed independently by Univ. of Wisconsin. The reprocessed AERI radiance data during the period 10/96 to 6/97 supercedes all previous versions of the AERI data in all instances. reprocessed, archived 9/99: sgpaeri01C1.00 reprocessed, archived 10/99: sgpaeri01ch1C1.a1 sgpaeri01ch2C1.a1 sgpaeri01engineerC1.a1 sgpaeri01summaryC1.a1 sgpaerilbldiffC1.c1 sgpaerilbldifflsC1.c1 sgplblch1C1.c0 sgplblch1C1.c1 sgplblch1lsC1.c0 sgplblch1lsC1.c1 sgplblch2C1.c0 sgplblch2C1.c1 sgplblch2lsC1.c0 sgplblch2lsC1.c1 sgpqmeaerilblC1.c1 sgpqmeaerilbllsC1.c1 sgpqmeaerimeansC1.c1 reprocessed, archived 11/99: sgpaeriprofC1.c1 sgpqmeaeriprofC1.c1 not reprocessed: sgpaerilblcloudsC1.c1 sgpaerilbldiffssC1.c1 sgpqmeaerilblssC1.c1 sgpqmeaerimeansssC1.c1 |
Measurements: | sgpaeri01ch1C1.a1:
sgpaerilbldiffC1.c1:
sgplblch2C1.c1:
sgpqmeaerimeansC1.c1:
sgpaeri01C1.00:
sgpaeri01ch2C1.a1:
sgplblch1lsC1.c1:
sgpqmeaerilblC1.c1:
sgpaeri01summaryC1.a1:
sgpaeriprofC1.c1:
sgplblch2lsC1.c1:
sgpqmeaerilbllsC1.c1:
sgpaerilbldifflsC1.c1:
sgplblch1C1.c1:
|