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SATURN-01 D.O.

Submitted by Sarah Riseman on November 13, 2012 - 11:26am

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.

SATURN-01

Quality Flag	start time	end time	comment
QL1	9/29/16 10:00	1/31/17	9/29/16 10:00 - 1/31/17: The DO sensor deployed at SATURN-01 on 9/29/16 had just been factory calibrated. Pre & post deployment sensor checks in aerated DI indicate that there was no calibration drift during this deployment. It should be noted that while the post-deployment check verified the sensor reading, there is an offset from concurrent data at SATURN-03 that were corrected for drift/fouling based on station readings of aerated DI
QL2	5/8/16	9/29/16 10:00	5/9/16 -9/29/16 10:00: The DO sensor deployed at SATURN-01was checked in 100% aerated DI prior to deployment and was found to be reading within manufacturer specifications. The sensor was replaced with freshly calibrated sensor on 9/29/16. The shift in data and comparison with data from SATURN-03 suggest that the recovered sensor was reading approximately 5% low at the time of recovery. The data between 5/9/16 & 9/29/16 were corrected for a linear drift to a 5% offset.
QL2	5/13/15	11/8/15	5/13/15 – 11/8/15 : The sensor deployed at SATURN-01 was cleaned and checked prior to deployment. It was found to be reading only slightly low (97%) in aerated DI. While there was no post-deployment sensor check, comparisons with data from other stations and with near-station data from a ship-board flow through sensor indicate that the sensor remained stable, with offsets of 0 to 3% low. The data have been flagged as QL2.
QL2	4/26/14	11/8/14	4/26/14 - 11/8/14: The sensor deployed at SATURN-01 was checked prior to and following deployment and was found to be reading 4-5% low. The sensor was routinely cleaned and short periods of sensor fouling have been identified and flagged. Comparisons with several near-station CTD casts are in agreement with the pre and post deployment checks, estimating the station sensor to be reading approximately 5% low. A correction has been applied to the data.
QL3	6/6/13	9/5/13	The sensor was factory calibrated on 1/11/13 and the calibration was verified on 4/18/13. It was deployed on 6/6/13 and recovered on 9/4/13. The post-deployment check of this sensor found it to be reading approximately 7.5% low compared to a freshly calibrated sensor in 100% oxygen saturated DI. A correction assuming linear drift has been applied and the data have been flagged as QL3. Note that problems regarding periodic insufficient flow across the sensor membrane appear to have been resolved for this deployment.
QL4	11/16/12	2/4/13	Installation of sensor during this period was vulnerable to insufficient flow across the sensor membrane during periods when the profiler is stationary or during low water velocity. DO readings during these periods appear to be artificially low. The data have been flagged as QL4 due to the issue with flow and should be used with extreme caution.
QL3	2/22/12	6/18/12	The sensor was newly calibrated by SeaBird Electronics and the calibration was checked against the YSI optode prior to deployment. No additional checks were made during its deployment and a post-deployment check was not possible due to a broken fitting. Comparisons with data from saturn03 data (which was shown to have a stable 4.5% offset during this time period) show that the sensor probably drifted slightly during deployment, but not more than 4.5%. However, installation of sensor was reconfigured on 2/22/12 to resolve issues with flow cell clogging. The new configuration is vulnerable to insufficient flow across the sensor membrane during periods when the profiler is stationary or during low water velocity and DO readings during these periods may be artificially low. This issue occurs predominantly, though not always, during periods of highest salinity. A process to identify the bad data is in development, but until these periods can be better delimited, these data should be used with caution. While the calibration quality has been assigned a level of quality level 2, the data have been flagged as quality level 3 until the issue with flow has been resolved or more precisely identified
QL2	2/9/12 15:35	2/22/12	The sensor was newly calibrated by SeaBird Electronics and the calibration was checked against the YSI optode prior to deployment. No additional checks were made during its deployment and a post-deployment check was not possible due to a broken fitting.
QL3	10/13/11	2/9/12 15:34	A calibration check on 10/13/11 found this sensor to be reading approximately 5 percent low. A calibration check on 2/6/11 found the sensor was reading approximately 10 percent low. A correction for linear drift during this time period from 5% to 10% offset has been applied to the data. Because there isn't a clear indication of when the drift occurred, the correction should be considered approximate and the data should be used with caution.
QL2	8/18/11 15:00	10/13/11	The sensor calibration was verified prior to deployment on 8/18/11. A sensor check on 10/13/11 found the sensor to be reading ~5% low. A correction assuming linear drift has been applied to the data.
QL3	8/4/11	8/18/11 15:00	The sensor calibration was verified on 4/25/11 but not immediately prior to re-deployment. Sensor failed so no post-deployment calibration check was possible. The calibration quality should be considered suspect because of the lack of independent calibration validation for this period.
QL1	8/3/10	4/25/11	The sensor was checked against a newly calibrated SBE sensor and a YSI hand-held on 12/7/11 and 12/8/11 and then again on 4/25/11. In all cases the sensor read approximately 2% high, verifying that the calibration was stable throughout this period and within +/- 2% .

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