http://lod.bco-dmo.org/id/dataset/933743
eng; USA
utf8
dataset
Highest level of data collection, from a common set of sensors or instrumentation, usually within the same research project
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
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2024-07-24
ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data
ISO 19115-2:2009(E)
Bottle-calibrated dissolved oxygen (DO) profiles from US Overturning in the Subpolar North Atlantic Program (OSNAP) cruises in 2020 and 2022 (AR45 and AR69-03)
2024-08-30
publication
2024-08-30
revision
Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)
2024-08-30
publication
https://doi.org/10.26008/1912/bco-dmo.933743.1
Hilary I. Palevsky
Boston College
principalInvestigator
Kristen E. Fogaren
Boston College
principalInvestigator
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
publisher
Cite this dataset as: Fogaren, K. E., Palevsky, H. I. (2024) Bottle-calibrated dissolved oxygen (DO) profiles from US Overturning in the Subpolar North Atlantic Program (OSNAP) cruises in 2020 and 2022 (AR45 and AR69-03). Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2024-08-30 [if applicable, indicate subset used]. doi:10.26008/1912/bco-dmo.933743.1 [access date]
Bottle-calibrated Dissolved Oxygen Profiles Dataset Description: Methods and Sampling: <p dir="ltr">These data were during cruises onboard the R/V Neil Armstrong to recover and redeploy mooring infrastructure of the international Overturning in the Subpolar North Atlantic Program (OSNAP) in 2020 (AR45) and 2022 (AR69-03). The mooring infrastructure maintained on these cruises is located in the eastern Labrador Sea (referred to as the LS line) and western Irminger Sea (referred to as the CF line). Beginning in 2020, the Gases in the Overturning and Horizontal circulation of the Subpolar North Atlantic Program (GOHSNAP) has added moored oxygen sensors to these sections of the OSNAP mooring array. During these cruises, Conductivity Temperature Depth (CTD) casts are conducted to provide data necessary to calibrate the moored sensors (Miller et al., in review), as well as hydrographic data that provide a valuable dataset in and of themselves.</p>
<p dir="ltr">This dataset uses CTD data collected by the OSNAP and GOHSNAP programs during AR45 (OSNAP 22) and AR69-03 (OSNAP 32) cruises, alongside discrete samples collected for this project during the cruises (Related Dataset: Palevsky et al. 2024) to produce calibrated, quality-controlled oxygen depth profiles. For further information on CTD-DO calibration and its role in the calibration of moored oxygen sensors, see Miller et al. (in review).</p>
<p dir="ltr"><em>Data collection&nbsp;</em></p>
<p dir="ltr">CTD casts were performed using a ship-provided SeaBird 911plus CTD and deck unit&nbsp; (http://www.seabird.com//sbe911plus-ctd) configured to measure pressure, temperature, conductivity, oxygen current, and other variables. Rosettes were equipped with primary and secondary pumped CTD sensor packages to measure pressure, temperature, and conductivity in duplicate. A SBE43 dissolved oxygen sensor was integrated into the pumped flow path of the primary CTD sensor package. Sensor data were acquired by an SBE Deck Unit providing demodulated data to a personal computer running SEASAVE (http://www.seabird.com/software/seasavev7) acquisition software. Calibrations for CTD sensors were performed by the manufacturer before the cruise.&nbsp;&nbsp;</p>
<p dir="ltr"><em>SeaBird processing&nbsp;</em></p>
<p dir="ltr">CTD data are processed using SeaBird data processing software. The raw 24 Hz CTD data are converted from HEX to ASCII, lag corrected, edited for large spikes, smoothed according to sensor, and pressure averaged into 2 db bins for final data quality control and analysis. Table 1 summarizes the order in which SeaBird Modules were processed and the inputs applied during each module.&nbsp;</p>
<p dir="ltr">SeaBird (Version 7.26.7) data processing module inputs&nbsp;</p>
<p dir="ltr">* DATCNV: Convert the raw data (.hex) to pressure, temperature, conductivity, and dissolved oxygen (V) to a file with a .cnv extension. Use default hysteresis correction<br />
* BOTTLESUM: Writes out a summary of the bottle data to a file with a .btl extension<br />
* ALIGNCTD: Advance Oxygen raw [V] by time determined by processing relative to pressure<br />
* WILDEDIT: Checks for and marks ‘wild’ data points: first pass 2.0 standard deviations; second pass 20 standard deviations&nbsp;<br />
* CELLTM: Conductivity cell thermal mass correction; alpha = 0.03 and 1/beta = 7.0<br />
* FILTER: Low pass filter pressure and depth (DO [V]) with a time constant of 0.15 seconds to increase pressure resolution for LOOPEDIT<br />
* LOOPEDIT: Mark scans where the CTD is moving less than the minimum velocity (0.25 m/s) or traveling backward due to ship roll<br />
* BINAVG: Average data into 2 db pressure bins to match bottle-calibrated salinity files&nbsp;<br />
* SPLIT (u or d): Split .cnv file into upcast and downcast files. Files are appended automatically with leading u or d</p>
Funding provided by NSF Division of Ocean Sciences (NSF OCE) Award Number: OCE-1947829 Award URL: https://www.nsf.gov/awardsearch/show-award?AWD_ID=1947829
Funding provided by NSF Division of Ocean Sciences (NSF OCE) Award Number: OCE-1947970 Award URL: https://www.nsf.gov/awardsearch/show-award?AWD_ID=1947970
Funding provided by NSF Division of Ocean Sciences (NSF OCE) Award Number: OCE-1947567 Award URL: https://www.nsf.gov/awardsearch/show-award?AWD_ID=1947567
completed
Hilary I. Palevsky
Boston College
617-552-4936
Boston College Dept of Earth and Environmental Sciences 140 Commonwealth Ave
Chestnut Hill
MA
02467
USA
palevsky@bc.edu
pointOfContact
Kristen E. Fogaren
Boston College
Boston College Department of Earth and Environmental Sciences
kristen.fogaren@bc.edu
pointOfContact
asNeeded
Dataset Version: 1
Unknown
Cruise
Station
Down_Up
Date_UTC
Lat
Lon
CTDPRES
CTDTEMP_ITS90
CTDTEMP_flag
CTDSAL_PSS78
CTDSAL_flag
CTDOXYCUR
CTDOXYCUR_flag
CTDOXY
CTDOXY_flag
file_name
SeaBird 911plus CTD
SeaBird SBE43 oxygen sensor
theme
None, User defined
Cruise identfier
station
cast type
date
latitude
longitude
water pressure
water temperature at measurement depth
flag
salinity
Oxygen in volts
dissolved Oxygen
file_name
featureType
BCO-DMO Standard Parameters
CTD Sea-Bird SBE 911plus
Sea-Bird SBE 43 Dissolved Oxygen Sensor
instrument
BCO-DMO Standard Instruments
AR45
AR69-03
service
Deployment Activity
otherRestrictions
otherRestrictions
Access Constraints: none. Use Constraints: Please follow guidelines at: http://www.bco-dmo.org/terms-use Distribution liability: Under no circumstances shall BCO-DMO be liable for any direct, incidental, special, consequential, indirect, or punitive damages that result from the use of, or the inability to use, the materials in this data submission. If you are dissatisfied with any materials in this data submission your sole and exclusive remedy is to discontinue use.
Collaborative Research: Gases in the Overturning and Horizontal circulation of the Subpolar North Atlantic Program (GOHSNAP)
https://osprey.bco-dmo.org/project/897705
Collaborative Research: Gases in the Overturning and Horizontal circulation of the Subpolar North Atlantic Program (GOHSNAP)
<p><strong>NSF Award Abstract:</strong><br />
Every winter, frigid winds blowing eastward from the North American continent cool the surface waters of the Labrador Sea, which is situated between Canada and Greenland. As the ocean cools, oxygen and carbon dioxide are mixed from the atmosphere into a thick layer of water that ultimately spreads southward to fill a large volume of the North Atlantic and beyond. The presence of this water mass prevents the North Atlantic anywhere from becoming completely devoid of oxygen. Vertical mixing in the Labrador Sea also redistributes carbon dioxide into the deep ocean, where it can remain for hundreds of years, preventing it from contributing to the greenhouse effect. Yet, the processes governing the uptake of gases by the ocean are not well understood or quantified. Given that, over the last century, the ocean has become steadily more depleted in oxygen while also absorbing a large fraction of anthropogenic carbon dioxide, observing gas exchange processes is essential for understanding and predicting the evolution of the ocean and climate system. The circulation of the Labrador Sea has been monitored since 2014 with an array of instrumented cables extending from the seafloor to nearly the ocean surface. This project adds gas sensors to this array to investigate the rates and processes governing gas exchange. Through this project, a student and postdoc will be trained in interdisciplinary oceanography with a rich network of international collaborators. Responding to the need to increase public ocean literacy, the project scientists will work with University of Rhode Island’s Inner Space Center to broadcast live, interactive science sessions to educators at partner high schools and will follow-up with in-person science cafés at three participating schools.</p>
<p>Given the unique role of the Labrador Sea in providing a pathway for oxygen (O2) and carbon dioxide (CO2) to enter the intermediate depths of the ocean, a quantification and mechanistic understanding of the gas uptake and transport in the basin is a leading scientific priority. Oxygenation of Labrador Sea water prevents large-scale hypoxia from developing anywhere in the Atlantic Ocean and anthropogenic CO2 storage in the basin is the highest in the global ocean. The assumption that, in the Atlantic Ocean, O2 and CO2 uptake and their variability are tied to the dynamics of heat loss and the overturning circulation pervades the literature but has never been evaluated on the basis of direct observations. Thus, GOHSNAP (Gases in the Overturning and Horizontal circulation of the Subpolar North Atlantic Program) addresses this gap and the urgent need to better understand interactions between gas uptake, transport, and the overturning circulation. Specifically, this program will provide a continuous 2-year record of the trans-basin, full water column transport of O2 across the southern boundary of the Labrador Sea, leveraging the mooring infrastructure of the US-lead, international Overturning in the Subpolar North Atlantic Program (OSNAP). The addition of O2 sensors at various depths on this array, supplemented by observations collected by autonomous platforms will allow for the quantification of O2 export from the Labrador Sea. The data will further be used to empirically model carbon concentrations and estimate carbon export. Proposed instruments will also measure the mixed layer O2 and pCO2 for two winters, from which air-sea gas exchange will be calculated and compared against analogous observations in the convective interior of the Labrador Sea.</p>
<p>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.</p>
GOHSNAP
largerWorkCitation
project
eng; USA
oceans
-68.522
-27.6994
41.9062
62.6272
2020-06-30
2022-09-23
Subpolar North Atlantic
0
BCO-DMO catalogue of parameters from Bottle-calibrated dissolved oxygen (DO) profiles from US Overturning in the Subpolar North Atlantic Program (OSNAP) cruises in 2020 and 2022 (AR45 and AR69-03)
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
http://lod.bco-dmo.org/id/dataset-parameter/936128.rdf
Name: Cruise
Units: unitless
Description: <p>Cruise identification (AR45 or AR69-03 )</p>
http://lod.bco-dmo.org/id/dataset-parameter/936129.rdf
Name: Station
Units: unitless
Description: <p>Station Identification</p>
http://lod.bco-dmo.org/id/dataset-parameter/936130.rdf
Name: Down_Up
Units: unitless
Description: <p>Down or up CTD cast ( d or u)</p>
http://lod.bco-dmo.org/id/dataset-parameter/936131.rdf
Name: Date_UTC
Units: unitless
Description: <p>Sampling date in ISO format (UTC time zone)</p>
http://lod.bco-dmo.org/id/dataset-parameter/936132.rdf
Name: Lat
Units: decimal degrees
Description: <p>Latitude in deceimal degrees, south is negative</p>
http://lod.bco-dmo.org/id/dataset-parameter/936133.rdf
Name: Lon
Units: decimal degrees
Description: <p>Longitude in decimal degrees, west is negative</p>
http://lod.bco-dmo.org/id/dataset-parameter/936134.rdf
Name: CTDPRES
Units: dbar
Description: <p>Hydrostatic pressure recorded from CTD at the depth where the sample was taken</p>
http://lod.bco-dmo.org/id/dataset-parameter/936135.rdf
Name: CTDTEMP_ITS90
Units: degrees Celsius
Description: <p>In situ temperature recorded from CTD on the ITS-90 scale</p>
http://lod.bco-dmo.org/id/dataset-parameter/936136.rdf
Name: CTDTEMP_flag
Units: unitless
Description: <p>WOCE quality control flag</p>
http://lod.bco-dmo.org/id/dataset-parameter/936137.rdf
Name: CTDSAL_PSS78
Units: unitless
Description: <p>Calibrated salinity (Practical Salinity Scale of 1978) calculated from conductivity recorded with CTD</p>
http://lod.bco-dmo.org/id/dataset-parameter/936138.rdf
Name: CTDSAL_flag
Units: unitless
Description: <p>WOCE quality control flag</p>
http://lod.bco-dmo.org/id/dataset-parameter/936139.rdf
Name: CTDOXYCUR
Units: volts
Description: <p>Oxygen current from the SeaBird SBE43 oxygen sensor on the CTD package processed with the SBE default hysteresis correction</p>
http://lod.bco-dmo.org/id/dataset-parameter/936140.rdf
Name: CTDOXYCUR_flag
Units: unitless
Description: <p>Quality control flag; see data documentation with this and Fogaren et al. dataset</p>
http://lod.bco-dmo.org/id/dataset-parameter/936141.rdf
Name: CTDOXY
Units: umol/kg
Description: <p>Calibrated dissolved oxygen content from oxygen sensor mounted on the CTD</p>
http://lod.bco-dmo.org/id/dataset-parameter/936142.rdf
Name: CTDOXY_flag
Units: unitless
Description: <p>Quality control flag; see data documentation with this and Fogaren et al. dataset</p>
http://lod.bco-dmo.org/id/dataset-parameter/936143.rdf
Name: file_name
Units: unitless
Description: <p>File name</p>
GB/NERC/BODC > British Oceanographic Data Centre, Natural Environment Research Council, United Kingdom
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
29225433
https://darchive.mblwhoilibrary.org/server/api/core/bitstreams/dfbd0e86-ded3-479d-9acb-b6276de47a31/content
download
https://doi.org/10.26008/1912/bco-dmo.933743.1
download
onLine
dataset
<p dir="ltr">These data were during cruises onboard the R/V Neil Armstrong to recover and redeploy mooring infrastructure of the international Overturning in the Subpolar North Atlantic Program (OSNAP) in 2020 (AR45) and 2022 (AR69-03). The mooring infrastructure maintained on these cruises is located in the eastern Labrador Sea (referred to as the LS line) and western Irminger Sea (referred to as the CF line). Beginning in 2020, the Gases in the Overturning and Horizontal circulation of the Subpolar North Atlantic Program (GOHSNAP) has added moored oxygen sensors to these sections of the OSNAP mooring array. During these cruises, Conductivity Temperature Depth (CTD) casts are conducted to provide data necessary to calibrate the moored sensors (Miller et al., in review), as well as hydrographic data that provide a valuable dataset in and of themselves.</p>
<p dir="ltr">This dataset uses CTD data collected by the OSNAP and GOHSNAP programs during AR45 (OSNAP 22) and AR69-03 (OSNAP 32) cruises, alongside discrete samples collected for this project during the cruises (Related Dataset: Palevsky et al. 2024) to produce calibrated, quality-controlled oxygen depth profiles. For further information on CTD-DO calibration and its role in the calibration of moored oxygen sensors, see Miller et al. (in review).</p>
<p dir="ltr"><em>Data collection&nbsp;</em></p>
<p dir="ltr">CTD casts were performed using a ship-provided SeaBird 911plus CTD and deck unit&nbsp; (http://www.seabird.com//sbe911plus-ctd) configured to measure pressure, temperature, conductivity, oxygen current, and other variables. Rosettes were equipped with primary and secondary pumped CTD sensor packages to measure pressure, temperature, and conductivity in duplicate. A SBE43 dissolved oxygen sensor was integrated into the pumped flow path of the primary CTD sensor package. Sensor data were acquired by an SBE Deck Unit providing demodulated data to a personal computer running SEASAVE (http://www.seabird.com/software/seasavev7) acquisition software. Calibrations for CTD sensors were performed by the manufacturer before the cruise.&nbsp;&nbsp;</p>
<p dir="ltr"><em>SeaBird processing&nbsp;</em></p>
<p dir="ltr">CTD data are processed using SeaBird data processing software. The raw 24 Hz CTD data are converted from HEX to ASCII, lag corrected, edited for large spikes, smoothed according to sensor, and pressure averaged into 2 db bins for final data quality control and analysis. Table 1 summarizes the order in which SeaBird Modules were processed and the inputs applied during each module.&nbsp;</p>
<p dir="ltr">SeaBird (Version 7.26.7) data processing module inputs&nbsp;</p>
<p dir="ltr">* DATCNV: Convert the raw data (.hex) to pressure, temperature, conductivity, and dissolved oxygen (V) to a file with a .cnv extension. Use default hysteresis correction<br />
* BOTTLESUM: Writes out a summary of the bottle data to a file with a .btl extension<br />
* ALIGNCTD: Advance Oxygen raw [V] by time determined by processing relative to pressure<br />
* WILDEDIT: Checks for and marks ‘wild’ data points: first pass 2.0 standard deviations; second pass 20 standard deviations&nbsp;<br />
* CELLTM: Conductivity cell thermal mass correction; alpha = 0.03 and 1/beta = 7.0<br />
* FILTER: Low pass filter pressure and depth (DO [V]) with a time constant of 0.15 seconds to increase pressure resolution for LOOPEDIT<br />
* LOOPEDIT: Mark scans where the CTD is moving less than the minimum velocity (0.25 m/s) or traveling backward due to ship roll<br />
* BINAVG: Average data into 2 db pressure bins to match bottle-calibrated salinity files&nbsp;<br />
* SPLIT (u or d): Split .cnv file into upcast and downcast files. Files are appended automatically with leading u or d</p>
Specified by the Principal Investigator(s)
<p dir="ltr"><strong>Post-processing SBE oxygen calibrations&nbsp;</strong></p>
<p dir="ltr">To produce the highest-quality oxygen measurements, post-processing procedures were modeled after methods described in Uchida et al. 2010. The following Seabird-recommended calibration equation was used to calibrate the SBE-43 oxygen sensor data:&nbsp;</p>
<p dir="ltr">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; O<sub>2</sub>= SOC(V+ Voff)* Oxysol(T,S)*(1 + A*T + B*T<sup>2</sup> + C*T<sup>3</sup>) * e<sup>E*p/(273.15 +T)</sup> (Equation 1)</p>
<p dir="ltr">where <em>O</em><em>2</em> is the CTD oxygen [μmol/kg], <em>V</em> is the output voltage signal processed with the SBE default hysteresis correction [volts], <em>Oxysol</em> is the oxygen saturation [μmol/kg], <em>T</em> is temperature [deg C], <em>S</em> is salinity [psu], and <em>P</em> is pressure [dbar] (SBE Application Note 64-2). Coefficients for the oxygen calibration slope (<em>SOCa</em>; voltage offset at 0 (<em>Voff</em>); temperature-related calibration coefficients of <em>A, B and C</em>; and pressure-related <em>E</em> term were determined initially from an 18-point factory calibration and provided by the manufacturer (Appendix A). <em>Voff, A, B,</em> and <em>C</em> are constant over the sensor life while values for <em>SOC</em> and <em>E</em> can be optimized using discrete water samples measured analytically for dissolved oxygen, and commonly referred to as Winklers.&nbsp;&nbsp;</p>
<p dir="ltr">Calibration coefficients for <em>SOC</em> and <em>E</em> were optimized by applying a non-linear least-squares fit to Winkler samples while calibration coefficients for <em>A, B, C</em>, and <em>Voff</em> were held constant. Oxygen sensor hysteresis due to pressure effects on the sensor membrane was improved by enabling the Seabird default hysteresis correction (Edwards et al. 2010; SBE Application Note 64-3). The optional response time correction, or <em>tau</em> correction, was determined to add excessive signal noise in relatively stable, deep portions of the water column; and, therefore, was not applied in the calibration equation.&nbsp;</p>
<p dir="ltr">While using this approach, a non-linear functional fit of Equation 1 was first attempted using one set of coefficients for the entire data set (whole cruise). Model fits were iterative with outliers discarded. Outliers were determined as values more than three scaled median absolute deviations from the median.&nbsp;</p>
<p dir="ltr">With outliers removed, residuals between CTD values and water sample values were then examined as a function of pressure, temperature, oxygen concentration, and cast number (≈ cruise time). An examination of the residuals as a function of cast number was used to 1) identify episodic events resulting in abrupt changes in <em>SOC</em> values, and 2) determine potential drift in <em>SOC</em> over the course of the cruise. After examining the residuals, cast numbers were grouped if necessary to minimize the residuals with an attempt to limit the number of groups used per cruise. New calibration coefficients were then determined for each group.</p>
<p dir="ltr">If a linear drift as a function of cast number (<em>cn</em>) or cruise time (<em>dt</em>) was determined for a group, a linear correction of the <em>SOC</em> drift was applied to the group while keeping other coefficients constant. The linear drift as a function of cast number/cruise time was then incorporated into the calibration equation, replacing <em>SOC</em> in Equation 1 as a function of cruise number/cruise time as:</p>
<p dir="ltr">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SOCcn/dt = SOC1 + F*cn/dt (Equation 2)</p>
<p dir="ltr">where <em>cn</em> or <em>dt</em> is the cast number [-] or time since first cast [d], respectively.<em> SOC</em>1 is the initial <em>SOC</em> value, and <em>F</em> is the rate of <em>SOC</em> change per cast number or day since first cast.&nbsp;&nbsp;&nbsp;</p>
<p dir="ltr">A nonlinear functional fit including the cast or time-dependent SOCcn/dt was then fit to the group determining coefficients for <em>E</em>, <em>SOC</em><em>1</em>, and <em>F</em> while holding <em>A, B, C,</em> and <em>Voff</em> constant. After iterative fitting and outliers removed, residuals were examined again as a function of pressure, temperature, oxygen concentration and cast number to ensure no linear dependence of residuals as a function of time. Outliers were determined as values more than three scaled median absolute deviations from the median.&nbsp;</p>
<p dir="ltr">For each cruise, CTD-derived measurements of salinity and oxygen solubility were calculated using the TEOS-10 Gibbs-SeaWater Oceanographic Toolbox (McDougall and Barker, 2011). Measurements from primary CTD sensors recorded in line with the SBE43 oxygen sensors were used to calculate oxygen concentrations unless collected data was poor. In these instances, measurements from the secondary CTD sensors were used. Bottle-calibrated CTD salinity measurements were used to produce oxygen concentrations. The measurements of temperature, salinity, pressure and oxygen voltage (processed with SBE default hysteresis correction; Application Note 64-3) used to produce oxygen concentration profiles are included in files for downcasts (indicated with ‘d’ appended) or upcasts (indicated with ‘u’ appended).&nbsp;&nbsp;&nbsp;</p>
<p dir="ltr">Throughout this documentation, oxygen profiles calibrated using a constant <em>SOC</em> value are indicated by <em>SOC</em><em>k</em> while oxygen profiles calibrated using an <em>SOC</em> term that varies with time or cast (station) number are indicated by <em>SOC</em><em>dt</em><em> </em>and <em>SOC</em><em>cn</em>, respectively. Lastly, oxygen sensor gain is determined as the Winkler-determined <em>SOC</em> value over the factory-determined <em>SOC</em> to assess changes in oxygen calibration slope since factory calibration. Note, the manufacturer recommends factory service inspection and calibration for a SBE43 DO sensor with a gain correction greater than 1.2 from the original factory value (Application Note 64-2).&nbsp;&nbsp;&nbsp;</p>
<p dir="ltr">&nbsp;</p>
<p dir="ltr"><strong>Deployment Cruise AR45&nbsp;</strong></p>
<p><em>Summary of Relevant Cruise Information</em></p>
<p dir="ltr">The AR45 Cruise Report (see cruise report in Pickart &amp; McRaven (2022)) was generated by participants of OSNAP22. The COVID-19 pandemic presented a number of challenges for sea-going operations in 2020. Traditionally, Winkler measurements are made at sea by trained technicians; however, to minimize shipboard personnel in 2020, discrete samples for oxygen were collected and stored according to methods described by Zhang et al. (2002) until subsequent analysis back on land. Results of discrete sample analyses for AR45 are available on BCO-DMO (related dataset: Palevsky et al. 2024).&nbsp;</p>
<p dir="ltr">A total of 163 CTD casts were performed on-board the R/V Armstrong. CTD-derived salinity data were calibrated by Leah McRaven at Woods Hole Oceanographic Institution using discrete bottle samples (Pickart and McRaven 2022). Conductivity and temperature data on this cruise were affected by biofouling issues and CTD pump issues. Issues with the CTD pump resulted in unphysical density inversions and uncharacteristic oxygen profiles in near surface waters for Casts 1-70. These pump-related density and oxygen issues were resolved by replacing the CTD package pump before Cast 71. The biofouling and pump issues are summarized in the AR45 CTD Calibration Report&nbsp;(see CTD calibration report in Pickart &amp; McRaven (2022)) The temperature, bottle-calibrated salinity and depth data from the primary CTD package were used in the oxygen sensor calibration equation to calibrate SBE43 (SN 1960) oxygen sensor data. The hysteresis between upcast and downcast oxygen data due to sensor response time was removed by advancing the oxygen sensor data 5 seconds relative to the pressure sensor data.&nbsp;</p>
<p dir="ltr"><em>Oxygen calibration Results</em></p>
<p dir="ltr">Calibration coefficients for <em>SOC</em> and <em>E</em> in Equation 1 were determined using a non-linear least squares fit between CTD oxygen values and 68 Winkler samples while calibration coefficients for <em>A, B, C,</em> and <em>Voff</em> were held constant at their factory-determined values (Appendix A). Residuals (Winkler - <em>SOC</em><em>k</em> model) determined using a constant <em>SOC</em> revealed no relationship between residuals and pressure, temperature, or oxygen concentration (Figure 1, supplemental file: AR45_OxygenCalibration_Results.pdf). The <em>SOC</em><em>k</em> model (RMSE = 0.78 μmol/kg, R2 = 0.995) flagged 9 Winkler samples (13.2%) as outliers. It was decided that only a constant <em>SOC</em> correction was appropriate for this cruise since 1) Winklers were not measured onboard, 2) Winklers were measured on just 4.3% of casts, and 3) negative relationship observed between <em>SOC</em> and time is not representative of typical electrochemical sensor drift (Application Note 64-2). The Winkler-optimized calibration coefficients and model results are summarized in Table 1. Oxygen data before and after calibration is shown in Figure 2 (supplemental file: AR45_AR6903_OxygenCalibrationResults_FiguresTables.pdf).</p>
<p dir="ltr">&nbsp;</p>
<p dir="ltr"><strong>Deployment Cruise AR69-03&nbsp;</strong></p>
<p><em>Summary of Relevant Cruise Information</em></p>
<p dir="ltr">The AR69-03 Cruise Report (see cruise report in Straneo (2023)) was generated by participants of OSNAP32. Results of discrete sample analyses for AR69-03 are available on BCO-DMO (Related Dataset: Palevsky et al. 2024). A total of 214 CTD casts were performed on-board the R/V Armstrong. CTD-derived salinity data were calibrated by Aaron Mau at Scripps Institution of Oceanography using discrete bottle samples, and results are summarized in the AR69-03 CTD Calibration Report&nbsp;(see CTD calibration report in Straneo (2023)). Temperature, bottle-calibrated salinity and depth data from the primary CTD package were used in the oxygen sensor calibration equation to calibrate SBE43 (SN 1960) oxygen sensor data. The hysteresis between upcast and downcast oxygen data due to sensor response time was removed by advancing the oxygen sensor data 5 seconds relative to the pressure sensor data.</p>
<p dir="ltr"><em>Oxygen calibration Results</em></p>
<p dir="ltr">Calibration coefficients for <em>SOC</em> and <em>E</em> in Equation 1 were attempted first using a non-linear least square fit between CTD oxygen values and the 585 Winkler samples collected on 82 unique casts. Resulting residuals were linearly correlated with temperature and oxygen concentration. Examination of Winkler residuals revealed issues with relatively high concentration Winklers collected in colder, surface waters. This may either indicate issues in the CTD dissolved oxygen sensor’s sensitivity and fit at these concentrations, or it may indicate a systematic measurement error in the Winkler dissolved oxygen analysis (for instance, due to possible oxygen degassing prior to sample collection and preservation). As such, Winklers greater than 316 μmol/kg were removed from this analysis, leaving 462 Winklers to determine oxygen sensor calibration coefficients.</p>
<p dir="ltr">The calibration coefficient for the <em>E</em> term in Equation 1 was determined using a non-linear least square fit between CTD oxygen values and 311 Winkler samples collected on 38 deep casts (deeper than 1000 m). The <em>SOC</em><em>k</em> model (RMSE = 0.840 μmol/kg, R2 = 0.993, n = 283) for deep casts flagged 28 Winkler samples (9.0%) as outliers. The calculated <em>E</em> term of 0.0372 was then held constant for the sensor over the duration of AR69-03 and the <em>SOC</em> calibration coefficient was optimized by breaking stations into groups.</p>
<p dir="ltr">Group 1: The calibration coefficient for <em>SOC</em> in Equation 1 was determined for Group 1 using a non-linear least square fit between CTD oxygen values and the 21 Winkler samples collected at Stations 1-2. Residuals (Winkler - <em>SOC</em><em>k</em> model) determined using a constant <em>SOC</em> revealed no relationship between residuals and pressure, temperature, station or oxygen concentration. The <em>SOC</em><em>k</em> model (RMSE = 0.191 μmol/kg, R2 = 1.00, n = 18) flagged 3 Winkler samples (14.3%) as outliers.</p>
<p dir="ltr">Group 2: Group 2 consisted of Stations 3-24, and application of the non-linear regression model using a time-dependent <em>SOC</em> term (Equation 2) was found to minimize the residuals between 109 collected Winklers and CTD oxygen. No relationship between residuals (Winkler- <em>SOC</em><em>dt</em> model) and pressure, temperature, station or oxygen concentration remained with the <em>SOC</em><em>dt</em> model fit. The <em>SOC</em><em>dt</em> model for Group 2 (RMSE = 0.517 μmol/kg, R2 = 0.998, n = 98) flagged 11 Winklers (10.1%) as outliers.</p>
<p dir="ltr">Group 3:&nbsp; The calibration coefficient for <em>SOC</em> in Equation 1 was determined for Group 3 using a non-linear least square fit between CTD oxygen values and the 59 Winkler samples collected at Stations 25-63. Residuals (Winkler - <em>SOC</em><em>k</em> model) determined using a constant <em>SOC</em> revealed no relationship between residuals and pressure, temperature, station or oxygen concentration. The <em>SOC</em><em>k</em> model (RMSE = 1.23 μmol/kg, R2 = 0.986, n = 51) flagged 8 Winkler samples (13.6%) as outliers.</p>
<p dir="ltr">Group 4: The calibration coefficient for <em>SOC</em> in Equation 1 was determined for Group 4 using a non-linear least square fit between CTD oxygen values and the 47 Winkler samples collected at Stations 64-82. Residuals (Winkler - <em>SOC</em><em>k</em> model) determined using a constant <em>SOC</em> revealed no relationship between residuals and pressure, temperature, station or oxygen concentration. The <em>SOC</em><em>k</em> model (RMSE = 0.614 μmol/kg, R2 = 0.998, n = 47) flagged no Winkler samples as outliers.</p>
<p dir="ltr">Group 5: Application of the non-linear regression model using a time-dependent <em>SOC</em> term (Equation 2) was found to minimize the residuals between the 65 Winklers collected and CTD oxygen at Stations 83-99. No relationship between residuals (Winkler- <em>SOC</em><em>dt</em> model) and pressure, temperature, station or oxygen concentration remained with the <em>SOC</em><em>dt</em> model fit. The <em>SOC</em><em>dt</em> model for Group 5 (RMSE = 0.699 μmol/kg, R2 = 0.993, n = 56) flagged 9 Winklers (13.9%) as outliers.</p>
<p dir="ltr">Group 6: The calibration coefficient for <em>SOC</em> in Equation 1 was determined for Stations 100-172 using a non-linear least square fit between CTD oxygen values and 134 Winkler samples. Residuals (Winkler - <em>SOC</em><em>k</em> model) determined using a constant <em>SOC</em> revealed no relationship between residuals and pressure, temperature, station or oxygen concentration. The <em>SOC</em><em>k</em> model (RMSE = 0.885 μmol/kg, R2 = 0.988, n = 116) flagged 18 Winkler samples (13.4%) as outliers.</p>
<p dir="ltr">Group 7: Application of the non-linear regression model using a time-dependent <em>SOC</em> term (Equation 2) was found to minimize the residuals between the 27 Winklers collected and CTD oxygen at Stations 173-214. No relationship between residuals (Winkler- <em>SOC</em><em>dt</em> model) and pressure, temperature, station or oxygen concentration remained with the <em>SOC</em><em>dt</em> model fit. The <em>SOC</em><em>dt</em> model for Group 7 (RMSE = 1.13 μmol/kg, R2 = 0.988, n = 25) flagged 2 Winklers (7.4%) as outliers.</p>
<p dir="ltr">Residuals as a function of pressure, station number, temperature, and concentration are shown for all 7 groups in Figure 3. The Winkler-optimized calibration coefficients and model results for the 7 groups are summarized in Table 2. Oxygen data before and after calibration is shown in Figure 4 (supplemental file: AR45_AR6903_OxygenCalibrationResults_FiguresTables.pdf).&nbsp;</p>
Specified by the Principal Investigator(s)
* Merged data from cruise AR45 and AR69-03 into 1 dataset
* Added ISO date notation to dataset
* Converted missing value flag 9 and missing identifier -999 to blank
Specified by BCO-DMO Data Managers
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For questions regarding this resource, please contact BCO-DMO via the email address provided.
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SeaBird 911plus CTD
SeaBird 911plus CTD
PI Supplied Instrument Name: SeaBird 911plus CTD Instrument Name: CTD Sea-Bird SBE 911plus Instrument Short Name:CTD SBE 911plus Instrument Description: The Sea-Bird SBE 911 plus is a type of CTD instrument package for continuous measurement of conductivity, temperature and pressure. The SBE 911 plus includes the SBE 9plus Underwater Unit and the SBE 11plus Deck Unit (for real-time readout using conductive wire) for deployment from a vessel. The combination of the SBE 9 plus and SBE 11 plus is called a SBE 911 plus. The SBE 9 plus uses Sea-Bird's standard modular temperature and conductivity sensors (SBE 3 plus and SBE 4). The SBE 9 plus CTD can be configured with up to eight auxiliary sensors to measure other parameters including dissolved oxygen, pH, turbidity, fluorescence, light (PAR), light transmission, etc.). more information from Sea-Bird Electronics Community Standard Description: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0058/
SeaBird SBE43 oxygen sensor
SeaBird SBE43 oxygen sensor
PI Supplied Instrument Name: SeaBird SBE43 oxygen sensor Instrument Name: Sea-Bird SBE 43 Dissolved Oxygen Sensor Instrument Short Name:SBE-43 DO Instrument Description: The Sea-Bird SBE 43 dissolved oxygen sensor is a redesign of the Clark polarographic membrane type of dissolved oxygen sensors. more information from Sea-Bird Electronics Community Standard Description: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0036/
Cruise: AR45
AR45
International Council for the Exploration of the Sea
R/V Neil Armstrong
vessel
AR45
Robert S. Pickart
Woods Hole Oceanographic Institution
https://doi.org/10.35090/gatech/66767
Report describing AR45
Cruise: AR69-03
AR69-03
International Council for the Exploration of the Sea
R/V Neil Armstrong
vessel
AR69-03
Fiamma Straneo
University of California-San Diego Scripps
https://cchdo.ucsd.edu/cruise/33VB20220819
Report describing AR69-03
International Council for the Exploration of the Sea
R/V Neil Armstrong
vessel