The table below contains the quality flag associated with dissolved oxygen calbration evaluations and the associated comments, beginning with the most recent. Refer to the QA/QC general information page for information on the different quality levels.
|Quality Flag||start time||end time||comment|
|QL2||7/1/20||12/1/20||CO-DEPLOYED SENSORS (see /s4-do06.pdf for details):
SBE63 (continued from earlier evalustions): Regular DI readings beginning in May 2020 suggest that the 17.6% calibration offset remained stable from early may through early October 2020. After 10/6/20, the sensor began drifting further. Based on weekly DI reading this drift appears to have been linear and reached an approximate calibration offset of 20.8% (in 100% aerated DI). The data have been corrected accordingly and corrections should be considered only approximate.
SBE43 (newly deployed): 9/22/20 – 12/1/20: The sensor was newly calibrated and reading within manufacturer specifications when deployed at the end of September. The sensor was reading approximately 12% low on 12/1/20. Calibration drift has been corrected based on DI data and linear drift during this time; corrections should be considered approximate.
|QL3||4/14/18||7/1/20||Multiple periods of drift beginning with the sensor reading approximately 5% low in 100% aerated DI water and ending at approximately 17% low. see supporting documentation for details on the different periods of drift and corrections: /s4-do05.pdf;|
|QL3||3/24/16 09:30||9/1/16||3/24/16 09:30 – 9/1/16: The sensor deployed at SATURN-04 in late February 2016 had a new factory calibration and was checked prior to deployment. An on-station DI reading prior to cleaning on 3/24/16 showed the sensor to be reading only slightly low (96.2% in 100% aerated DI), however, following cleaning there was a ~5% drop in the sensor readings (in addition to the existing 4% offset). Subsequent on-station aerated DI readings through August 2016 have shown the sensor offset to have remained stable and the sensor to be reading approximately 9% low. A correction factor has been applied to the data between 3/24/16 & 9/1/16 for a 9% offset.|
|QL2||2/23/16||3/24/16||2/23/16 11:30 – 3/24/16 09:25: The sensor deployed at SATURN-04 in late February 2016 had a new factory calibration and was checked prior to deployment. On-station DI reading prior to cleaning on 3/24/16 showed the sensor to be reading slightly low (96.2% in 100% aerated DI). A correction for linear drift to a 3.8% offset on 3/24/16 offset has been applied to the data. Comparisons with other station data support this offset assessment.|
|QL4||11/5/15||2/23/16||11/5/15 -2/23/16 11:00: The SATURN-04 sensor was recovered and tested on 11/5/15. Prior to re-deployment, the sensor was reading only slightly low (97.5% in 100% aerated DI water). An on-station DI reading made on 2/23/16, made just prior to the sensor being recovered again, indicated that the sensor was reading ~15% low. A newly calibrated sensor was installed and the resulting shift in data support this assessment. Comparison with data from other stations indicate that this offset extended back to mid-December 2015. A correction for a drift to an ~15% offset between 11/5 & 12/15/15 followed by a stable 15% offset through 2/23/16 was applied to the data. Because of the extent of sensor offset, and limited data for evaluation of the onset of sensor drift, these data should be used with caution and have been flagged as poor (QL4).|
|QL3||11/8/14||10/30/15||11/8/14 – 10/30/15: The SATURN-04 sensor was recovered and tested on 11/8/14. Following cleaning, the sensor was reading approximately 6% low prior to re-deployment. Following recovery on on 10/30/15 the sensor was reading approximately 11% low prior to being cleaned and serviced. Routine on-station aerated DI measurements and comparisons with near-station CTD casts and data from a ship-board flow through sensor indicate that the sensor offset remained stable at ~10% low from approximately mid-November through June. Corrections for these offsets have been applied to the data.|
|QL3||2/20/14||11/8/14||2/20/14 -11/8/14: The sensor was recovered and tested on 2/20/14. After cleaning it was reading approximately 95.1% in 100% aerated DI water. The sensor was re-deployed for another 9.5 months and recovered and tested again on 11/8/14. At this point the sensor reading was 90.8% in 100% aerated DI indicating the sensor drifted over the course of the deployment. The on-station readings support linear interpretation of the sensor drift, although indicate that the sensor may have been reading form 0.5% to 3% lower than is suggested by the sensor cross-checks. The data have been corrected for drift using the sensor check data.|
|QL3||4/9/14||2/20/14||4/9/13 -2/20/14: A mid-deployment calibration check on 4/8/13 found this sensor to be reading within manufacturer specifications (98.9% in 100% aerated DI). The sensor was recovered and checked again on 2/20/14 and was found to be reading approximately 10% low. Data from routine aerated DI readings and comparison with near station cast data indicate that the drift was linear. The data have been corrected for linear drift between 4/8/13 and 2/20/14. For additional details, see QA/
QC document s4-do01.pdf in the DO QA/QC Archive.
|QL1||1/23/12||4/8/13||1/23/13 – 4/9/13: A mid-deployment calibration check on 1/23/13 found this sensor to be reading within ~2.5% of three freshly calibrated sensors. Another calibration check on 4/8/13 found the sensor to be reading within 1% of the reference instruments. The calibration has been flagged as good (QL1) during this time period.|
|QL2||12/17/12||1/23/13||12/17/12 – 1/23/13: A pre-deployment check found the sensor readings to be reading within ~3.5% of a freshly calibrated sensor and a hand-held YSI optical DO sensor. The sensor was recovered and tested against 3 newly calibrated sensors and was found to be reading within 2.5%.|
|QL3||6/18/12||12/14/12||The sensor was freshly calibrated by SeaBird inc. and a pre-deployment check found the sensor readings to be in agreement with 4 other newly calibrated sensors. The sensor was recovered on 12/13/12 and a calibration evaluation found the sensor to be reading approximately 8% low relative to a sensor that had been freshly calibrated by seabird. A correction assuming linear drift from the point of deployment to a final offset of 8% on 12/13/12 has been applied to the data. This correction is approximate and data have been flagged as QL3 because the drift exceeded 5%.|
|QL1||6/1/12||6/18/12||Sensor was newly calibrated prior to deployment and a sensor check on 6/18/12 found the calibration to be within 1%.|
|QL3||9/23/11||2/16/12||The DO sensor was newly calibrated by SBE prior to deployment and a pre-deployment check verified the sensor calibration. The sensor was recovered from the station for a calibration check on 10/13/11 where it read 8-9% low. It was redeployed and recovered again on 2/6/12 where it read 2-3% low against a newly calibrated SBE43 and within 1% of the YSI hand-held optode. Given the drop in response followed by a partial recovery, data during this time have been flagged as suspect and the data should be used with caution.|
|QL1||5/12/11 14:00||8/16/11 16:40||The DO sensor was newly calibrated by SBE prior to deployment. A post-deployment check showed that the sensor read ~3.5% high against the YSI optode in a well stirred, aerated tank.|
|QL2||4/26/11 12:00||5/12/11 13:00||A pre-deployment check showed this sensor to be within 2% of a freshly calibrated YSI hand-held optode. While the sensor calibration was not verified with a post-deployment check, oxygen percent saturation data were in agreement with the Saturn-03 DO sensor which had a verified calibration during this time. Data should be considered probably good.|
|QL2||1/26/11 12:45||3/1/11 16:20||A pre-deployment calibration check against a YSI hand-held optode verified that the sensor calibration was good. No post deployment check was possible due to membrane failure caused by freezing temperatures. Therefore, sensor drift, if any, cannot be evaluated for this deployment. Data during this period should be considered probably good.|
|QL4||9/23/09||1/26/11||The first DO sensor deployed at Saturn04 was deployed for approximately 16 months prior to the implementation of calibration verification protocols (9/23/09 – 1/26/11). When the sensor was recovered from the station in January, 2011 a calibration check showed that the sensor was reading approximately 36% low. Based on the oxygen percent saturation, three periods separated by abrupt changes in percent saturation are evident. Corrections based on these periods have been developed and applied to the data. From 9/29/09 to 10/3/09, percent saturation values are near 100% (excluding about a week of bad data at the beginning of the deployment) and the data during this period are not adjusted. However, because there are no independent quality control measurements during this time and the sensor was recovered over a year later reading significantly low, data from this time period should still be considered ‘probably bad’ and used with caution. For the full details of this correction see the quality control supporting documentation.|