| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D000203.2 | SGP/AOS/C1 - Humidograph water circulation system failure | sgpaosC1.a0 |
| D000203.3 | SGP/AOS/C1 - CN counter removed | sgpaosC1.a0 |
| D000801.3 | SGP/AOS/C1 - Nephelometer failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D000801.4 | SGP/AOS/C1 - Nephelometer failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D000801.5 | SGP/AOS/C1 - Nephelometer failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D020709.3 | SGP/AOS/C1 - AOS Computer Failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D021007.1 | SGP/AOS/C1 - Ozone instrument out of service | sgpaosC1.a0, sgpaosauxC1.a0 |
| D030210.1 | SGP/AOS/C1 - Data missing | sgpaosC1.00, sgpaosC1.a0, sgpaosauxC1.a0 |
| D040130.1 | SGP/AOS/C1 - Ozone Instrument removed for repair | sgpaosC1.a0, sgpaosauxC1.a0 |
| D041026.3 | SGP/AOS/C1 - PCASP instrument problem | sgpaosC1.a0, sgpaosauxC1.a0 |
| D041026.4 | SGP/AOS/C1 - Ozone instrument removed for repair | sgpaosC1.a0, sgpaosauxC1.a0 |
| D041026.5 | SGP/AOS/C1 - Condensation Particle Counter failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D041026.6 | SGP/AOS/C1 - Wet nephelometer problems | sgpaosC1.a0, sgpaosauxC1.a0 |
| D050120.2 | SGP/AOS/C1 - Failed RH sensor | sgpaosC1.a0 |
| D050401.1 | SGP/AOS/C1 - wet nephelometer out of service | sgpaosC1.a0 |
| D980505.1 | SGP/AOS/C1 - Annual Maintenance | sgpaosC1.a0 |
| D980513.1 | SGP/AOS/C1 - Single wavelength nephelometer pump failure | sgpaosC1.a0 |
| D980526.1 | SGP/AOS/C1 - PSAP Flow Rate Change | sgpaosC1.a0 |
| D980527.2 | SGP/AOS/C1 - Single-wavelength nephelometer errors | sgpaosC1.a0 |
| D980527.3 | SGP/AOS/C1 - 3-wavelength nephelometer failure | sgpaosC1.a0 |
| D980527.4 | SGP/AOS/C1 - Condensation Particle Counter failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980528.1 | SGP/AOS/C1 - Optical Particle Counter (PCASP-X) down | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980528.10 | SGP/AOS/C1 - Instrument communications problems | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980528.2 | SGP/AOS/C1 - 3-wavelength nephelometer data missing | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980528.6 | SGP/AOS/C1 - Ozone instrument left in span mode | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980528.7 | SGP/AOS/C1 - Line 8 bypass in wrong position | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980528.8 | SGP/AOS/C1 - Light absorption photometer (PSAP) error | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980528.9 | SGP/AOS/C1 - Ozone Instrument Communication Failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980529.1 | SGP/AOS/C1 - Ozone Instrument data incorrect | sgpaosC1.a0, sgpaosauxC1.a0 |
| D980731.1 | SGP/AOS/C1 - Aerosol sampling system and nephelometer failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D981203.1 | SGP/AOS/C1 - 3-wavelength nephelometer data missing | sgpaosC1.a0, sgpaosauxC1.a0 |
| D981223.2 | SGP/AOS/C1 - Intermittent leak in AOS spare sampling line and thermal sensitivity | sgpaosC1.a0 |
| D990611.1 | SGP/AOS/C1 - Ozone Instrument Failure | sgpaosC1.a0, sgpaosauxC1.a0 |
| D990614.1 | SGP/AOS/C1 - Invalid absorption data | sgpaosC1.a0, sgpaosauxC1.a0 |
| D990618.1 | SGP/AOS/C1 - Incorrect absorption and scattering data | sgpaosC1.a0 |
| D990809.1 | SGP/AOS/C1 - Ozone instrument error | sgpaosC1.a0, sgpaosauxC1.a0 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/02/1999 | 2300 | 01/15/2000 | 0000 |
| Subject: | SGP/AOS/C1 - Humidograph water circulation system failure |
| DataStreams: | sgpaosC1.a0 |
| Description: | The water circulation system for the AOS humidograph failed. Consequently, the humidified nephelometer was reporting aerosol light scattering values during this period that were close to what the reference nephelometer was observing. The difference between the two sets of measurements reflect particle losses in the humidifier and different temperature environments for the two instruments. Humidified nephelometer data during this period are technically valid, they just do not reflect relative humidity scans (the normal operating mode). |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/16/1999 | 0448 | 01/15/2000 | 0000 |
| 07/08/2002 | 1131 | 08/05/2002 | 1424 |
| Subject: | SGP/AOS/C1 - CN counter removed |
| DataStreams: | sgpaosC1.a0 |
| Description: | The AOS condensation particle counter performance degraded to unacceptable levels and was removed for repair. For the first time period: upon inspection of the internal condition of the instrument, it was found that oil was present in the intake line. It is unknown how this oil could have arrived in this position. The instrument was thoroughly cleaned and back-flushed, and returned to service during the maintenance visit. For the second time period: The degradation of began July 8th. Data collected during this time period are either incorrect or missing and should not be used. |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/02/2000 | 1842 | 06/16/2000 | 2234 |
| Subject: | SGP/AOS/C1 - Nephelometer failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | An inexperienced AOS technician inadvertently closed off the flow to the dual-nephelometer humidograph system during a Friday Preventative Maintenance. This resulted in liquid water getting into the humidified nephelometer. Flow was restored to the system on Monday, but the nephelometers were producing strange data. A number of tests were performed over the next few days to remotely troubleshoot the situation, to no avail. Eventually, the decision was made to pull both nephelometers and return them to Boulder for repair. This DQR refers only to the reference nephelometer, which was out of service for 2 periods due to 2 separate problems. This DQR is for the first period, from 000602 (1842 GMT) to 000616 (2234 GMT). Light absorption are invalid whenever the reference nephelometer is not operational, because those data are required for correction of the absorption data. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/20/2000 | 1340 | 07/03/2000 | 1833 |
| Subject: | SGP/AOS/C1 - Nephelometer failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | An inexperienced AOS technician inadvertently closed off the flow to the dual-nephelometer humidograph system during a Friday Preventative Maintenance. This resulted in liquid water getting into the humidified nephelometer. Flow was restored to the system on Monday, but the nephelometers were producing strange data. A number of tests were performed over the next few days to remotely troubleshoot the situation, to no avail. Eventually, the decision was made to pull both nephelometers and return them to Boulder for repair. This DQR refers only to the reference nephelometer, which was out of service for 2 periods due to 2 separate problems. This DQR is for the second period, from 000620 (1340 GMT) to 000703 (1833 GMT). Light absorption measurements are invalid whenever the reference nephelometer is not operational, because those data are required for correction of the absorption data. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/02/2000 | 1842 | 07/03/2000 | 1833 |
| Subject: | SGP/AOS/C1 - Nephelometer failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | An inexperienced AOS technician inadvertently closed off the flow to the dual-nephelometer humidograph system during a Friday Preventative Maintenance. This resulted in liquid water getting into the humidified nephelometer. Flow was restored to the system on Monday, but the nephelometers were producing strange data. A number of tests were performed over the next few days to remotely troubleshoot the situation, to no avail. Eventually, the decision was made to pull both nephelometers and return them to Boulder for repair. This DQR refers only to the humidified nephelometer, which was out of service for the entire period from 000602 through 000703. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 05/23/2002 | 2011 | 05/26/2002 | 2033 |
| 05/27/2002 | 0232 | 05/28/2002 | 1439 |
| 05/29/2002 | 0258 | 05/29/2002 | 1516 |
| 05/29/2002 | 2159 | 05/30/2002 | 1113 |
| 05/31/2002 | 2310 | 06/04/2002 | 1447 |
| Subject: | SGP/AOS/C1 - AOS Computer Failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The AOS computer started to experience periodic failures caused by an aging and failing system disk. Replacement of the AOS computer's system disk occurred between 2-4 June 2002. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/30/2002 | 0000 | 10/01/2002 | 1934 |
| Subject: | SGP/AOS/C1 - Ozone instrument out of service |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The ice storm of 30-31 January, 2002 shut down the AOS for ~2 weeks. A controlled power-up of the system found a problem with the ozone monitor. Smoke was observed to come from the ozone instrument, at which time it was shut down. The ozone monitor was removed from the AOS for remote troubleshooting. The cause of the smoke was identified as being from underneath a printed circuit board. At that point, Site Ops staff were requested to send the unit to Boulder for additional troubleshooting. NOAA staff received the unit on 20 February 2002. After a brief inspection, the cause of the smoking was discovered. A one-half inch hole was burned completely through the motherboard. The determination was made that this could not be repaired at the NOAA facility, and a purchase order was initiated to return the unit to Dasibi, Inc. (the manufacturer), for repair/replacement of the motherboard. On 4 March, 2002, NOAA personnel received the OK from ARM to return the instrument to Dasibi, Inc. for service. Dasibi, Inc., received the unit on or around 8 March, 2002. The manufacturer was to test the unit, repair or replace the damaged motherboard, and calibrate the unit according to the NIST standard protocol. On 8 May, 2002, NOAA personnel emailed SGP Site Ops personnel and asked them to check on the status of the repair, which was taking longer then expected. Upon trying to contact the manufacturer, it was discovered that they went out of business. The return of instruments from the manufacturer to customers was being handled by a contract company. The ozone monitor arrived back in Boulder, in an unrepaired state, on or about 1 July 2002. Since there were few other options, NOAA personnel undertook the difficult task of repairing the motherboard. This required the re-routing of several electrical conduits from the burned area in the multilayer board to other acceptable places on the board. This took a considerable amount of electronics technician time and effort. After the motherboard was repaired, extensive testing was required to verify that the repair was done successfully and that other problems were not caused in the unit by the board burning.. The repair was deemed successful on 24 September, 2002. The unit was shipped back to the SGP site immediately thereafter. It was installed during a NOAA AOS maintenance visit on 1 October, 2002. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/27/2002 | 1805 | 12/31/2002 | 1543 |
| Subject: | SGP/AOS/C1 - Data missing |
| DataStreams: | sgpaosC1.00, sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The UPS supplying power to the AOS computer failed on Friday, 12/27/2002. The UPS was repaired on Monday 12/30/2002, but the AOS computer was locked up and would not reboot. Telephone communication was established with Richard Eagan, ANL, who was able to do a remote reboot of the computer using his account. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.00:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/21/2003 | 1636 | 01/27/2004 | 2208 |
| Subject: | SGP/AOS/C1 - Ozone Instrument removed for repair |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The ozone instrument was removed for calibration on 2003 11/21. It was shipped to Boulder and was cleaned and calibrated. It was sent back to SGP on 2003 12/02, but was damaged in transit by FedEx. The instrument was reinstalled on 2003 12/03 but was found to be defective. Large spikes were observed in the data. Afetr a few days the instrument was removed and shipped to a vendor for repair. The ozone monitor was returned to service after repair at 2004 01/27 (2208 GMT). |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/10/2004 | 0000 | 10/26/2004 | 1200 |
| Subject: | SGP/AOS/C1 - PCASP instrument problem |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | PCASP (optical particle counter) gave unusually low aerosol signal counts despite numerous attempts to fix the instrument by the mentor and manufacturer. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/21/2003 | 1600 | 01/28/2004 | 0000 |
| Subject: | SGP/AOS/C1 - Ozone instrument removed for repair |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The ozone monitor was removed and sent back to the manufacturer for repair. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/28/2004 | 1400 | 08/27/2004 | 1540 |
| Subject: | SGP/AOS/C1 - Condensation Particle Counter failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The CPC signal declined to a low value. The instrument was shipped back to the mentor, cleaned and repaired. The instrument inlet was clogged. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/24/2004 | 0000 | 02/18/2004 | 1800 |
| Subject: | SGP/AOS/C1 - Wet nephelometer problems |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The humidifier tube was coated with mold and had to be replaced. This affects the wet nepheleometer measurements and the calculations of the aerosol hygroscopic growth. The humidifer was cleaned and replaced. A filter was added to the water circulation to minimize mold. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/01/2004 | 0000 | 05/01/2005 | 2359 |
| Subject: | SGP/AOS/C1 - Failed RH sensor |
| DataStreams: | sgpaosC1.a0 |
| Description: | The RH sensor inside the humidified nephelometer began to slowly decline in value in the upper RH range beginning in early 2004 and becoming more noticable poor on 20041117. The sensor currently reaches a high RH value of about 60% when the actual RH is closer to 80%. The sensor was replaced in the Spring of 2005, but the problem remained. Effective 1/1/2004, this sensor is not used to calculate scientific data and is therefore essentially abandoned in the field. An end-date of 20050501 is being used as a placeholder. |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 03/04/2005 | 0000 | 03/22/2005 | 1955 |
| Subject: | SGP/AOS/C1 - wet nephelometer out of service |
| DataStreams: | sgpaosC1.a0 |
| Description: | The humidified nephelometer was removed and shipped back to CMDL to test and work on the relative humidity sensor inside the instrument. |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 08/04/1997 | 1459 | 08/08/1997 | 1348 |
| 04/20/1998 | 1449 | 04/23/1998 | 2136 |
| 07/19/1999 | 1452 | 07/30/1999 | 1829 |
| 01/10/2000 | 1400 | 01/15/2000 | 0000 |
| 09/30/2002 | 1300 | 10/04/2002 | 1900 |
| 03/17/2003 | 1547 | 03/21/2003 | 2248 |
| Subject: | SGP/AOS/C1 - Annual Maintenance |
| DataStreams: | sgpaosC1.a0 |
| Description: | The AOS Annual maintenance/calibration visit occurred during these periods. During these times, instruments were cleaned, calibrated, and when necessary, repaired. Instruments were online collecting data for some of the time; however, periods of contamination are probable because aerosol sampling lines were opened for inspection and cleaning and pumps were switched off for periods of time. Any data fields during this period that contain data should be considered incorrect. |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/08/1998 | 1900 | 04/16/1998 | 1630 |
| Subject: | SGP/AOS/C1 - Single wavelength nephelometer pump failure |
| DataStreams: | sgpaosC1.a0 |
| Description: | The pump failed on the single-wavelength nephelometer line. The vacuum gauge also failed, giving vacuum readings that made it appear that the pump was still working. Technicians reported that the pump was still working during this period, although the vacuum gauge read slightly lower than expected. The nephelometer was measuring aerosol scattering inside the scattering volume, which over time showed consistently low scattering values. This problem was difficult to diagnose given the faulty vacuum gauge and the fact that the site experienced relatively low ambient aerosol scattering values during this period. The repair was made just prior to the AOS annual maintenance visit in April 1998. The only field in the AOS data files that was affected was Field 29, "Bscat530nm". |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/03/1995 | 0000 | 05/26/1998 | 1910 |
| Subject: | SGP/AOS/C1 - PSAP Flow Rate Change |
| DataStreams: | sgpaosC1.a0 |
| Description: | The AOS PSAP flow rate was reduce due to data becoming noisy at the end of each weekend, probably due to the decrease in the dynamic range of the instrument experienced when the filter is heavily loaded. The flow rate of the PSAP was decreased from its previous nominal value of 0.90 standard liters per minute to 0.75 standard liters per minute on 5/26/98 at 1910 GMT. This should lessen the aerosol deposit buildup at the end of the weekends |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/16/1997 | 2010 | 06/20/1997 | 1313 |
| Subject: | SGP/AOS/C1 - Single-wavelength nephelometer errors |
| DataStreams: | sgpaosC1.a0 |
| Description: | Due to a malfunctioning bypass valve, the single wavelength nephelometer was not properly sampling ambient air. Thus, scattering values during this period are incorrect. The incorrect data field is "Bscat530nm". |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/24/1997 | 1652 | 06/26/1997 | 1847 |
| Subject: | SGP/AOS/C1 - 3-wavelength nephelometer failure |
| DataStreams: | sgpaosC1.a0 |
| Description: | The backscatter shutter on the TSI 3-wavelength nephelometer failed and the unit had to be replaced. Data are either missing or incorrect. |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/30/1997 | 0707 | 07/08/1997 | 1946 |
| 08/27/1997 | 1400 | 09/16/1997 | 1355 |
| Subject: | SGP/AOS/C1 - Condensation Particle Counter failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | During the time periods specified, the AOS Condensation Particle Counter was down for maintenance. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/01/1997 | 0936 | 07/03/1997 | 1556 |
| 08/01/1997 | 1329 | 08/08/1997 | 1348 |
| 05/05/1998 | 0926 | 06/16/1998 | 1505 |
| 06/09/1999 | 0824 | 07/26/1999 | 2205 |
| 09/08/2000 | 0426 | 10/13/2000 | 1630 |
| 05/17/2002 | 0602 | 05/20/2005 | 1847 |
| 05/23/2002 | 2011 | 05/31/2002 | 1258 |
| 09/09/2002 | 0000 | 10/07/2002 | 1905 |
| Subject: | SGP/AOS/C1 - Optical Particle Counter (PCASP-X) down |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The AOS Optical Particle Spectrometer (PCASP-X sizing probe) was down during these periods. This lowers the laser reference voltage and results in inaccurate sizing. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/12/1997 | 2023 | 12/15/1997 | 1834 |
| Subject: | SGP/AOS/C1 - Instrument communications problems |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | Several of the AOS instruments apparently lost communications with the AOS computer during this period. These instruments were the TSI 3-wavelength nephelometer, the PSAP light absorption photometer, and the Dasibi ozone instrument. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/29/1997 | 1340 | 07/31/1997 | 2236 |
| Subject: | SGP/AOS/C1 - 3-wavelength nephelometer data missing |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The AOS TSI 3-wavelength nephelometer lost communications with the AOS data system during this period. Cause of the communications break is unknown. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 08/29/1997 | 1348 | 09/02/1997 | 1326 |
| Subject: | SGP/AOS/C1 - Ozone instrument left in span mode |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | AOS Ozone instrument was left in span mode over the weekend. Span value was logged during this period. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 09/15/1997 | 1540 | 09/16/1997 | 1420 |
| Subject: | SGP/AOS/C1 - Line 8 bypass in wrong position |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The Line 8 bypass valve was stuck in the wrong position. Consequently, air was not being drawn through the TSI 3-wavelength nephelometer and the PSAP light absorption photometer, and thus they were not measuring ambient (outdoor) aerosols. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 09/23/1997 | 1440 | 09/24/1997 | 1700 |
| Subject: | SGP/AOS/C1 - Light absorption photometer (PSAP) error |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The AOS continuous light absorption photometer (PSAP) showed inaccurate data during this period due to a filter being inserted into the optical assembly incorrectly. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/28/1997 | 2030 | 12/01/1997 | 1514 |
| 03/20/1998 | 1849 | 03/23/1998 | 2147 |
| Subject: | SGP/AOS/C1 - Ozone Instrument Communication Failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The AOS Ozone instrument apparently lost communications with the AOS computer during these periods. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/02/1998 | 1634 | 01/08/1998 | 1634 |
| Subject: | SGP/AOS/C1 - Ozone Instrument data incorrect |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | A filter of the wrong type was placed in the ozone instrument intake line. This filter destroys ozone, and consequently the measured ozone values during this period are abnormally low. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/10/1998 | 0435 | 07/28/1998 | 2053 |
| Subject: | SGP/AOS/C1 - Aerosol sampling system and nephelometer failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The electronic valve that switches the aerosol sampling system from sampling the total aerosol (D<10 um) to the submicrometer (D<1 um) aerosol began having intermittent positioning problems. All 3-wavelength nephelometer and light absorption photometer data collected during this time period should be viewed as suspect, since we can't be sure what particle size range was being sampled at any time. During this interval, the nephelometer lamp became unstable and finally blew, giving no nephelometer data for the end of this period. The period of lamp failure in the AOS data files can be recognized by prolonged periods of missing value codes for aerosol scattering and nephelometer housekeeping channels. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/05/1998 | 1558 | 11/12/1998 | 0501 |
| Subject: | SGP/AOS/C1 - 3-wavelength nephelometer data missing |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | The AOS data system lost communications initially with the 3-wavelength TSI nephelometer. A communications port on the Sun workstation became locked, and attempts to unlock it were unsuccesful. Stopping and restarting the data collection software did not solve the problem. Missing value codes were being generated for all TSI nephelometer measurements and parameters. The decision was made to reboot the workstation. On 981110, at 1555 GMT, the workstation was rebooted. We discovered then that we did not have the proper root user password to log back onto the system and restart the software. From 981110 (1555GMT) to 981112 (0501GMT) no data were being logged by the AOS data system. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/19/1998 | 1830 | 10/08/1998 | 1925 |
| Subject: | SGP/AOS/C1 - Intermittent leak in AOS spare sampling line and thermal sensitivity |
| DataStreams: | sgpaosC1.a0 |
| Description: | Starting on 980619, periodic fluctuations in several of the measured AOS parameters (e.g.,
Aerosol light absorption coefficent, TSI nephelometer relative humidity, condensation
particle counts, etc.) were observed. The start of these fluctuations coincided exactly
with the shutdown of the AOS for power washing of the wooden stairs and stack platform.
Numerous attempts at troubleshooting were conducted via telephone with technicians at the site.
These concentrated on 1) trying to find an electrical noise problem or 2) determining
whether our stack heating unit was somehow producing particles. Tests were devised to check
both of these possibilities, and both were determined to be non-problems. The
troubleshooting of this signal fluctuation problem was compounded and delayed by the concurrent
unrelated electronic ball valve problem (see AOS DQR#980731.1).
Pat Sheridan and Jim Wendell from the NOAA Aerosols Group went to the SGP Central Facility
to diagnose and repair the problem. All electromagnetic noise possibilities, including
bad grounds and RF fields were checked. These were not causing the fluctuations, which
varied in period from ~15-30 minutes. Upon dismantling the insulated air intake assembly
inside the trailer, a minute crack was found in one of the spare sampling lines at its
connection to the manifold. This line was one of the original installed by the previous mentor.
Repair of this line break essentially repaired the fluctuation problem, although this
extensive troubleshooting revealed a slight temperature dependence for some of our reference
signals (more on this below).
Our explanation of this problem is as follows. When the AOS stairs were power washed,
either the activities associated with power washing (e.g. people or compressors on the
platform) or lowering the stack caused enough vibration to cause a hairline break in the spare
sampling line at the connection with the manifold. We believe this tubing is
high-density polyethylene, which is semi-rigid, and it has now been replaced with less brittle
material. The routine daily system zero checks established by the previous mentor would not
have detected this leak problem, because overpressurization of the manifold with
particle-free air showed up as good zero checks in all instruments and some of this clean air
would have simply flowed out of the spare line tubing crack. Since the crack was beneath at
least two layers of foam insulation which itself was covered with foam-backed metallic
tape, we believe that free air flow of trailer air to the crack was not likely. However,
during periods when the large air conditioning unit was on, pressurization of the trailer
caused air to slowly leak into the spare sampling line and back into the manifold and
other sampling lines. Upon arrival at the site, we found the fan for the A/C system
operating only when the A/C compressor came on. We were informed by Dan Nelson, Site Engineer,
that this fan is supposed to stay on all the time. Our data suggest that this fan has
been off since before the problem began. This is fortuitous, because the trailer was not
continually pressurized and room air was not sampled continuously over this period.
Thus, only a portion of the data are of questionable quality. This leak was not immediately
obvious (to AOS technicians or to us) because of its concealed location and because some
aerosol measurements (e.g., particle number concentrations, aerosol light absorption
coefficents, etc.) did not change dramatically during these periods (i.e., the aerosols
brought inside the trailer through the cooling system were often not much different in
concentration or optical properties than were aerosols sampled at the top of the stack). Thus
data during the A/C periods will be labeled as questionable.
We will institute a new leak check/zero check procedure which should catch leaks of this
type. The old system zero check devised by the previous mentor was insufficient to find
this leak.
The A/C unit in the AOS trailer is more than adequate to cool that space. The cold air
that comes out of the vents is probably >20F cooler than trailer air. This cold air causes
slight fluctuations in the lamp voltages and reference signals of several of our
instruments. We expect this problem to be more severe in the summertime because of increased
air conditioner use and indoor temperature swings. Fortunately, these signal fluctuations
are not observed in the final processed signals from these instruments. They do,
however, suggest that a gentler cooling of the trailer should be considered.
Possibilities for this could include:
1) Installation of a smaller air conditioning unit
2) Changing the ratio of outside air mixed in with the cooled air
3) Venting the exhaust from the cabinets into the air recirculating
system to preheat the cooled air.
We realize that these suggestions may not be in line with the notion of efficient cooling
of the trailer. However, we feel that the root cause of the observed temperature
fluctuations is that the air conditioning unit has far more capacity than is needed by the AOS
trailer. A smaller air conditioner, properly matched to the heat load of the trailer,
would probably be a more efficient solution.
Since the cooling of the trailer generally was faster than the warming-up period, a
majority of data should be valid. Also, not all measurements appeared questionable (i.e., the
data did not appear to change when the A/C unit came on). We have flagged all aerosol
data as "questionable" during A/C "on" periods because of the likelihood that at least some
mixing of trailer air with ambient air occurred. |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 05/07/1999 | 1556 | 05/14/1999 | 1445 |
| Subject: | SGP/AOS/C1 - Ozone Instrument Failure |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | A malfunction occurred with the AOS surface ozone instrument during the period 990507 1556 GMT to 990514 1445 GMT. The instrument reported an ozone concentration of 9.91e-01 ppm (991 ppb) continuously during this time. Quality checking of the data the following week revealed that the problem began at about the time weekly maintenance check was made on Friday. The problem continued until the next weekly maintenance check was done. Site Ops was notified by the mentor of the problem on Friday, 5/14/99, and a technician was sent to inspect the system. No switches on the instrument front panel were found in the wrong position (for example, if the instrument was inadvertantly left in a calibration mode). By the time the technician arrived at the trailer, the instrument appeared to be working correctly. No explanation is given as to why these erroneous values were being generated by the ozone instrument, except that possibly it locked up with the throwing of the weekly preventative maintenance switch and this problem was not corrected until the same switch was thrown the following week. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 05/21/1999 | 1413 | 05/27/1999 | 1819 |
| Subject: | SGP/AOS/C1 - Invalid absorption data |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | During the period noted, a valve position error with the 1-um/10-um impactor switching valve occurred. The result of this error was to invalidate all switched data. The software correctly inserted missing value codes in the nephelometer data, but the PSAP light absorption photometer for some reason reported a constant value over this period. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 05/21/1999 | 1348 | 05/27/1999 | 1822 |
| Subject: | SGP/AOS/C1 - Incorrect absorption and scattering data |
| DataStreams: | sgpaosC1.a0 |
| Description: | The electronically switched valve that alternately switches flow through 1-um and 10-um impactors showed an error during this time period. This error invalidated all downstream data. In the raw data files, aerosol light scattering coefficients for the TSI reference and humidified nephelometers were assigned missing value codes. The aerosol light absorption coefficient was observed to stick at a constant value over this period. The problem went away after the weekly maintenance was performed, although nothing specific was done to the valve. The flipping of the maintenance switch appears to have solved the problem. |
| Measurements: | sgpaosC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/18/1999 | 1628 | 06/22/1999 | 1537 |
| 06/25/1999 | 1630 | 06/28/1999 | 1343 |
| Subject: | SGP/AOS/C1 - Ozone instrument error |
| DataStreams: | sgpaosC1.a0, sgpaosauxC1.a0 |
| Description: | A switch on the front panel of the ozone instrument was left in the wrong position. This resulted in a bad value for ozone concentration being logged for these periods. |
| Measurements: | sgpaosauxC1.a0:
sgpaosC1.a0:
|