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SATURN-07 D.O.

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-07

Quality Flag start time end time comment
QL2 5/1/18 5/1/19 5/1/18 - 5/1/19:  The dissolved oxygen sensor deployed at SATURN-07 in early May 2018 was checked with aerated DI water prior to deployment and in situ after two weeks of deployment.  These measurements showed the sensor calibration to be reading within manufacturer specifications.  Comparison with quality controlled data from SATURN-03 suggest that the sensor calibration did not drift through September 2018.  The data diverge from QC data at SATURN-03 in the beginning of October and appear to be approximately 5% lower than those data.
QL3 2/5/16 2/1/17 2/5/16 - 2/1/17:  The SATURN-07 sensor deployed on 2/5/16 was checked prior to deployment and was found to be reading only slightly outside of manufacturer specifications (96.7% in 100% aerated DI) The sensor was checked in situ on 3/31/16 and read 98% in 100% aerated DI, and a post-recovery sensor check on 1/30/17 found the sensor to be reading 99% in 100%aerated DI, suggesting no fouling or drift of the sensor over the course of the deployment.  However, oxygen saturations were lower than would be expected during this time and comparison to data from other SATURN stations during this time period also suggest that the sensor was reading low.  A correction for the initial offset of 3% has been applied to the entire deployment and the data have been flagged as QL3 due to the uncertainty in the presence/extent of sensor drift.
QL4 8/23/15 2/4/16 8/23/15 – 2/4/15:  Comparisons with quality controlled data from SATURN-03 suggest that the sensor began to drift rapidly between 8/23/15 and 8/29/15, reaching an offset in the range of 15%.  The sensor appears to have remained reading at least 15% low until the sensor was recovered on 2/4/16.   There also appears to have been two periods of additional sensor drift beyond the 15%, followed by abrupt recovery (returning it to a 15% offset).  These occured between 9/19/15 & 10/30/15 and between 10/31/15 & 1/12/16.  These events could have been caused by a partial blocking and then clearing of the flow cell.  All data after 8/23/15 have been corrected based comparison with SATURN-03 data on the observed data-shifts.  These corrections are approximate only and are not supported by any monitoring data.  The data have therefor been flagged as poor (QL4) and should be used with caution.   For details, consult the QC documentation (http://www.stccmop.org/books/qaqc_dissolved_oxygen)
QL1 7/29/15 8/23/15 2/5/15:  The SATURN-07 sensor deployed on 2/5/16 was checked prior to deployment and was found to be reading only slightly outside of manufacturer specifications (96.7% in 100% aerated DI).   A preliminary correction for this slight offset has been applied to the data.  Following additional QC based on future monitoring data and the quality assessment will be updated.
QL4 6/9/15 7/29/15  6/9/15 – 7/29/15 10:30:  Comparison with data from a ship-board flow-through sensor on 5 cruises showed a steady increase of sensor offset from ~6% on 3/19 to ~12.6% on 6/9/15.   A correction for a sensor offset of 12.6% was extended until 7/29/15 when the station was visited and the buoy was raised and serviced.  Continuing an offset estimate of  12-13% through 7/29 was supported by comparison with quality controlled data from SATURN-03.  While a correction has been applied, these data have been flagged as poor (QL4) and should be used with caution, due to the extent of offset and because there are limited data to support the applied correction during this period.  For details and supporting data, consult the QC documentation (http://www.stccmop.org/books/qaqc_dissolved_oxygen)
QL3 3/19/15 6/9/15 3/19/15 – 6/9/15:  Comparison with data from a ship-board flow-through sensor on 5 cruises showed a steady increase of sensor offset from ~6% on 3/19 to ~12.6% on 6/9/15. A correction for sensor offset, based on linear drift during this time, has been applied to the data.  For details and supporting data, consult the QC documentation (http://www.stccmop.org/books/qaqc_dissolved_oxygen)
QL2 1/1/15 3/19/15 1/15/15 – 3/19/15:  The SATURN-07 sensor checked prior to deployment and was found to be reading approximately 5% low.  Comparison with data from a ship-board flow-through sensor on 4 cruises between 1/27/15 and 3/19/15 showed the sensor offset increased only slightly to ~6% on 3/19/15.  Corrections for these offsets have been applied to the data.  For details and supporting data, consult the QC documentation (http://www.stccmop.org/books/qaqc_dissolved_oxygen)
QL3 5/1/14 11/1/14 5/1/14 - 11/1/14:   A sensor check in February indicated that this sensor was reading ~5% low.  The post-deployment check found this sensor to be reading ~11% high and comparison with data from a near-station CTD cast in mid-October also estimated the sensor to be reading ~10%high.  A correction for linear drift from the point of deployment to the point of recovery has been applied.  It should be noted that it is highly unusual for these sensors to drift toward reading high. Data should be used with caution.
QL2 10/31/13 12/7/13 This sensor was checked in aerated DI water prior to deployment and was found to be reading slightly low (97%) and the calibration has been flagged as QL2.   Note: The majority of data from this deployment are bad due to sensor malfunction or clogging. There are two short periods of data that appear to be g ood, however , they have been flagged as QL3 due to the overarching issues with this deployment
QL2 5/23/13 10/19/13 5/23/13 - 10/19/13: Prior to this time, comparison with near-station CTD data and a pre-deployment check showed the sensor calibration to be good.  Data from another CTD cast on 6/20/13 suggest the sensor may have begun to drift slightly.  The post-deployment calibration check found the sensor be reading only slightly outside of manufacturer specifications of 100% +/- 2% (97% in 100% aerated DI).  The calibration during this period has been flagged as QL2.
QL1 4/23/13 5/23/13 This sensor was factory calibrated on 3/24/12 and deployed on 4/23/13. Comparisons with oxygen data from CTD casts conducted on station on 5/1/13, 5/16/13 and 5/22/13 suggest the sensor was reading within calibration during this time.  The CTD sensor was verified in 100% saturation DI prior to the cruise. 
QL1 12/4/12 3/22/13 While there was no pre or post deployment sensor checks, multiple CTD casts on station indicate that the sensor was reading within calibration.  Station sensor readings are within 1% of data from CTD casts on 2/14/13, 2/28/13, 3/14/13 and 3/21/13.  The CTD sensor calibration was verified prior to the cruises.