BOCATS 2023. CTD-02 Data Report

Caroline Le Bihan, Pascale Lherminier, Philippe Le Bot, Michel Hamon, Fiz F Pérez

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Caroline Le Bihan, Pascale Lherminier, Philippe Le Bot, Michel Hamon, Fiz F Pérez. BOCATS 2023. CTD-02 Data Report. Ifremer. 2024. hal-05373447

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# BOCATS 2023

## CTD-O₂ Data report

Caroline Le Bihan, Pascale Lherminier, Philippe Le Bot, Michel Hamon and Fiz F. Pérez

<figure><img src="image_2.png" /></figure>

EXPOCODE: 29AH20230608

GO-SHIP section A25 (OVIDE-BOCATS)
Cite as: Le Bihan Caroline, Lherminier Pascale, Le Bot Philippe, Hamon Michel (2024).
BOCATS 2023 CTD-O2 data report. Ifremer, LOPS. https://archimer.ifremer.fr/

Date release: November 26, 2024
ABSTRACT

BOCATS 2023 cruise focused on the 11th repetition of the OVIDE section. OVIDE (BOCATS) cruises have been run biennially since 2002, always in June-July, and the section is labelled as a high-resolution reference section in the international program GO-SHIP. BOCATS 2023 started in Vigo on June 8 and ended in Reykjavik on July 14 on the R/V Sarmiento de Gamboa. The 98 stations of the OVIDE section, from Portugal to the tip of Greenland, could be realized in totality. The core of the work consisted in acquiring surface-to-bottom hydrographic profiles of pressure, temperature, salinity and dissolved oxygen, and analyzing 14 physical and biogeochemical tracers from 11 920 samples drawn from the Niskin bottles of the CTD frame. We report here a focus on the acquisition and calibration steps of the physical variables measured specifically by the hydrographic CTD-O₂ probe.

After calibration, we find precisions for pressure, temperature, salinity and dissolved oxygen that fit the GO-SHIP international quality requirements. Pressure and temperature were calibrated at the laboratory before and after the cruise, leading to a repeatability better than 1 dbar and 0.001 °C respectively. The calibration of salinity and dissolved oxygen data is obtained by applying polynomial correcting functions that are calculated to statistically minimize the differences between the probe data and the sample data analyzed on board in the chemistry container. These chemical data are also evaluated by the comparison of replicates. After calibration, the differences in salinity and oxygen follow a zero-centered Gaussian-like distribution which standard deviation is used to evaluate the probe precision for each variable. For salinity, we find a standard deviation of 0.001, and for oxygen, 0.021 ml/l (or 1 µmol/kg). Those numbers correspond to a 68 % confidence interval and must be doubled to obtain the precision within a 95 % confidence interval.

The final dataset is available on Seanoe: https://doi.org/10.17882/95607
Table des matières

<table><tr><td>ABSTRACT</td><td>3</td></tr><tr><td>The BOCATS 2023 Cruise</td><td>7</td></tr><tr><td>1.1 Introduction</td><td>7</td></tr><tr><td>1.2 Cruise participants</td><td>8</td></tr><tr><td>1.3 Description of cruise operations</td><td>9</td></tr><tr><td>1.4 Station list</td><td>10</td></tr><tr><td>1.5 Overview of the operations and main technical problems during the cruise</td><td>15</td></tr><tr><td>2 General information about data acquisition</td><td>17</td></tr><tr><td>2.1 Equipment</td><td>17</td></tr><tr><td>2.2 CTD Acquisition Protocol</td><td>18</td></tr><tr><td>2.3 Sampling protocol</td><td>18</td></tr><tr><td>3 Chronological steps applied to the CTD-O2 data</td><td>19</td></tr><tr><td>3.1 Pre-cruise activity</td><td>19</td></tr><tr><td>3.2 During the cruise</td><td>19</td></tr><tr><td>3.3 Post-cruise treatment</td><td>19</td></tr><tr><td>4 CTD probe measurements</td><td>20</td></tr><tr><td>4.1 Pressure measurements</td><td>20</td></tr><tr><td>4.2 Temperature measurements</td><td>21</td></tr><tr><td>4.2.1 Calibration of the temperature sensors at Ifremer metrology laboratory</td><td>21</td></tr><tr><td>4.2.2 Correction of the temperature measurements on the CTD profiles</td><td>21</td></tr><tr><td>4.2.3 Validation of the CTD temperature measurements</td><td>21</td></tr><tr><td>4.3 Conductivity measurements</td><td>23</td></tr><tr><td>4.4 Oxygen measurements</td><td>23</td></tr><tr><td>5 Salinity and oxygen samples analysis</td><td>24</td></tr><tr><td>5.1 Equipment</td><td>24</td></tr><tr><td>5.2 Salinity analysis</td><td>25</td></tr><tr><td>5.2.1 General protocol</td><td>25</td></tr><tr><td>5.2.2 Replicates in salinity</td><td>25</td></tr><tr><td>5.3 Oxygen analysis</td><td>26</td></tr><tr><td>5.3.1 General protocol</td><td>26</td></tr><tr><td>5.3.2 Replicates in oxygen</td><td>26</td></tr><tr><td>6 Post-cruise treatment</td><td>27</td></tr><tr><td>6.1 Data preparation</td><td>27</td></tr><tr><td>6.1.1 Data cleaning with Hydro_net</td><td>27</td></tr><tr><td>6.1.2 Correction of the hysteresis on O2 measurements</td><td>28</td></tr><tr><td>6.1.3 Bottle file</td><td>28</td></tr></table>
<table><tr><td>6.2</td><td>Seabird treatment</td><td>28</td></tr><tr><td>6.3</td><td>Data adjustment</td><td>29</td></tr><tr><td>6.3.1</td><td>Concatenation of the bottle files and creation of a chemical file</td><td>30</td></tr><tr><td>6.3.2</td><td>Determination of the correction in Conductivity/Salinity</td><td>30</td></tr><tr><td></td><td>Operating mode</td><td>30</td></tr><tr><td></td><td>Analysis of the initial results and choice of the polynomial correction</td><td>31</td></tr><tr><td>6.3.3</td><td>Application of the correction</td><td>33</td></tr><tr><td>6.3.4</td><td>Update of the chemical file</td><td>36</td></tr><tr><td>6.3.5</td><td>Calculation of the polynomial correction in oxygen</td><td>36</td></tr><tr><td></td><td>Operating mode</td><td>36</td></tr><tr><td></td><td>Analysis of the initial results and choice of the polynomial correction</td><td>36</td></tr><tr><td>6.3.6</td><td>Application of the correction</td><td>39</td></tr><tr><td>6.3.7</td><td>Final update of the chemical file</td><td>41</td></tr><tr><td>6.3.8</td><td>Reduction in O2 and netcdf files creation</td><td>42</td></tr><tr><td>6.4</td><td>Data final validation</td><td>42</td></tr><tr><td>6.4.1</td><td>Validation of the Oxygen profiles</td><td>42</td></tr><tr><td>6.4.2</td><td>Density inversions</td><td>43</td></tr><tr><td>6.4.3</td><td>Correction of the flags of oxygen bottle data</td><td>44</td></tr><tr><td>7</td><td>Precision of the BOCATS 2023 measurements</td><td>46</td></tr><tr><td>8</td><td>Sections</td><td>47</td></tr><tr><td>9</td><td>Bibliography</td><td>52</td></tr><tr><td>10</td><td>Acknowledgments</td><td>52</td></tr><tr><td></td><td>Figure table</td><td>53</td></tr><tr><td></td><td>Appendix</td><td>54</td></tr><tr><td></td><td>Figures of the CTD and associated bottle data</td><td>63</td></tr></table>
# The BOCATS 2023 Cruise

## 1.1 Introduction

The BOCATS 2023 cruise took place on board the R/V Sarmiento de Gamboa from 8th of June to 14th of July, starting at Vigo (Spain) and finishing at Reykjavik (Island).

<figure><img src="image_3.png" /><figcaption>Figure 1: R/V Sarmiento de Gamboa</figcaption></figure>

The working area is between Portugal and Greenland (see fig. 2).

<figure><img src="image_4.png" /><figcaption>Figure 2: map of the working area, with zooms in the Iberian and Greenland areas. Blue lines delimit coasts and EEZ limits and green lines the 3 and 12 Nm national waters. Black and white dots are CTD stations (white when numbered and circled in green when the VMP was deployed), red triangles are positions of float deployments, and the stations with redpoints was sampled for genomics.</figcaption></figure>
## 1.2 Cruise participants

<table><thead><tr><td>Names</td><td>Organism</td><td>Responsibility on board</td></tr></thead><tbody><tr><td>Fiz Fernández Pérez</td><td>IIM-CSIC</td><td>Chief scientist</td></tr><tr><td>Marcos Morente Fontela</td><td>CCMAR</td><td>DOC</td></tr><tr><td>Xose Antonio Padín Alvarez</td><td>IIM-CSIC</td><td>Sampling + genomics</td></tr><tr><td>Marta López Mozos</td><td>IIM-CSIC</td><td>pH + alkalinity</td></tr><tr><td>Sara Camaselle Vazquez</td><td>IIM-CSIC</td><td>pH + alkalinity</td></tr><tr><td>Maria Lopez Acosta</td><td>IIM-CSIC</td><td>Nutrients</td></tr><tr><td>Pilar Camaselle Salgado</td><td>IIM-CSIC</td><td>Nutrients</td></tr><tr><td>Daniel Fernández Román</td><td>UVIGO</td><td>VMP</td></tr><tr><td>Javier Lopez Fernández</td><td>UVIGO</td><td>Sampling</td></tr><tr><td>Aide Lasa González</td><td>UVIGO</td><td>Sampling + genomics</td></tr><tr><td>Jakob Ernst</td><td></td><td>Sampling</td></tr><tr><td>Pascale Lherminier</td><td>IFREMER</td><td>Resp. physics data (CTD, ADCP) + forecasts</td></tr><tr><td>Caroline Le Bihan</td><td>IFREMER</td><td>Chemistry supervision and CTD calibration</td></tr><tr><td>Raphael Bajon</td><td>IFREMER</td><td>CTD watch (0-4) and sampling</td></tr><tr><td>Aliette CHENAL</td><td>MERCATOR/CNES</td><td>CTD watch (8-12) and sampling</td></tr><tr><td>Ludovic Cosmes</td><td>IFREMER</td><td>CTD watch (4-8) and sampling</td></tr><tr><td>Philippe Le Bot</td><td>IFREMER</td><td>chemistry, O2</td></tr><tr><td>Michel Hamon</td><td>IFREMER</td><td>chemistry, salinity</td></tr><tr><td>Iago Lopez Rodriguez</td><td>CSIC</td><td>Technical resp.</td></tr><tr><td>Manuel Garcia Salazar</td><td>UTM</td><td>CTD watch</td></tr><tr><td>David Angel Fernandez Fontaiña</td><td>UTM</td><td>CTD watch</td></tr><tr><td>Raoul Vicente Guillot Miralles</td><td>UTM</td><td>CTD watch</td></tr></tbody></table>

<figure><img src="image_5.png" /><figcaption>Figure 3: Scientific team and UTM crew members</figcaption></figure>
1.3 Description of cruise operations

The following operations were carried out during the cruise:

* 6 stations in Vigo ria (Figure 4, data not included in this report)

<figure><img src="image_6.png" /><figcaption>Figure 4: stations in the Ria of Vigo</figcaption></figure>

* 106 CTD stations with O₂, Salinity, pH total, alkalinity, Carbone total, nitrous oxide, Nutrients, Oxygen 18 sampling:

* 1 test station (number 0).

* 107 OVIDE CTD stations (1-98) with 3 casts for the station 68, 5 stations for genomics sampling (called "cast 2" of stations 10, 30, 45, 62 and 83) and 1 station in the Eriador eddy (110)

* 13 CTD stations on a short shelf-break section and on the AR24 section (northern section in Fig.2)

<figure><img src="image_7.png" /><figcaption>Figure 5: Synoptic chart indicating the sampling levels for CTD</figcaption></figure>

* 5 Argo floats launched (Deep).

* SADCP measurements (Ship Acoustic Doppler Current Profiler, 75 and 150 kHz data acquisition).

* Underway measurements (Thermosalinometer monitoring).

* VMP
1.4 Station list

<table><thead><tr><th>Station #</th><th>Cast #</th><th>Latitude begin</th><th>Longitude begin</th><th>Date begin</th><th>Latitude end</th><th>Longitude end</th><th>Date end</th><th>Latitude mean</th><th>Longitude mean</th><th>2023 day mean</th><th>Station durat. (min.)</th><th>CTD max depth</th><th>Bottom depth</th></tr></thead><tbody><tr><td>0</td><td>1</td><td>40.33344</td><td>-10.00605</td><td>2023/06/09 16:12:49</td><td>40.33343</td><td>-10.00607</td><td>2023/06/09 18:13:20</td><td>40.333</td><td>-10.006</td><td>160.7174</td><td>121</td><td>3535</td><td>3547</td></tr><tr><td>1</td><td>1</td><td>40.33343</td><td>-9.45996</td><td>2023/06/09 21:27:10</td><td>40.33343</td><td>-9.45996</td><td>2023/06/09 21:36:29</td><td>40.33343</td><td>-9.45996</td><td>160.8971</td><td>9</td><td>145</td><td>154</td></tr><tr><td>2</td><td>1</td><td>40.33332</td><td>-9.64266</td><td>2023/06/09 23:07:37</td><td>40.33332</td><td>-9.64271</td><td>2023/06/09 23:37:00</td><td>40.33332</td><td>-9.64269</td><td>160.9738</td><td>29</td><td>423</td><td>429</td></tr><tr><td>3</td><td>1</td><td>40.33329</td><td>-9.7668</td><td>2023/06/10 01:06:10</td><td>40.3333</td><td>-9.76678</td><td>2023/06/10 01:46:24</td><td>40.333</td><td>-9.767</td><td>161.0599</td><td>40</td><td>801</td><td>807</td></tr><tr><td>4</td><td>1</td><td>40.33324</td><td>-9.80501</td><td>2023/06/10 13:59:26</td><td>40.33325</td><td>-9.80502</td><td>2023/06/10 14:58:21</td><td>40.333</td><td>-9.805</td><td>161.6034</td><td>59</td><td>1463</td><td>1477</td></tr><tr><td>5</td><td>1</td><td>40.33338</td><td>-9.87688</td><td>2023/06/10 05:41:32</td><td>40.33338</td><td>-9.87688</td><td>2023/06/10 07:23:31</td><td>40.333</td><td>-9.877</td><td>161.2726</td><td>102</td><td>2449</td><td>2479</td></tr><tr><td>6</td><td>1</td><td>40.33335</td><td>-9.946</td><td>2023/06/10 09:13:43</td><td>40.33335</td><td>-9.946</td><td>2023/06/10 11:44:07</td><td>40.333</td><td>-9.946</td><td>161.4367</td><td>150</td><td>3412</td><td>3421</td></tr><tr><td>7</td><td>1</td><td>40.33334</td><td>-10.03711</td><td>2023/06/10 17:33:48</td><td>40.33347</td><td>-10.03694</td><td>2023/06/10 19:52:51</td><td>40.333</td><td>-10.037</td><td>161.7801</td><td>139</td><td>3517</td><td>3527</td></tr><tr><td>8</td><td>1</td><td>40.33335</td><td>-10.30198</td><td>2023/06/10 21:46:45</td><td>40.33335</td><td>-10.30198</td><td>2023/06/11 00:32:20</td><td>40.333</td><td>-10.302</td><td>161.965</td><td>166</td><td>3894</td><td>3904</td></tr><tr><td>9</td><td>1</td><td>40.33332</td><td>-10.57693</td><td>2023/06/11 02:34:31</td><td>40.33332</td><td>-10.57695</td><td>2023/06/11 05:11:13</td><td>40.333</td><td>-10.577</td><td>162.1617</td><td>157</td><td>4341</td><td>4361</td></tr><tr><td>10</td><td>1</td><td>40.33338</td><td>-10.90502</td><td>2023/06/11 11:54:34</td><td>40.33337</td><td>-10.90504</td><td>2023/06/11 14:52:47</td><td>40.333</td><td>-10.905</td><td>162.5581</td><td>178</td><td>4842</td><td>4851</td></tr><tr><td>10</td><td>2</td><td>40.33333</td><td>-10.90502</td><td>2023/06/11 07:20:10</td><td>40.33333</td><td>-10.90501</td><td>2023/06/11 09:56:14</td><td>40.333</td><td>-10.905</td><td>162.36</td><td>156</td><td>4423</td><td>4851</td></tr><tr><td>11</td><td>1</td><td>40.33344</td><td>-11.34288</td><td>2023/06/11 18:02:34</td><td>40.33343</td><td>-11.34288</td><td>2023/06/11 21:12:22</td><td>40.333</td><td>-11.343</td><td>162.8177</td><td>190</td><td>5088</td><td>5099</td></tr><tr><td>12</td><td>1</td><td>40.33316</td><td>-11.78278</td><td>2023/06/12 00:14:21</td><td>40.33317</td><td>-11.78274</td><td>2023/06/12 03:19:24</td><td>40.333</td><td>-11.783</td><td>163.0742</td><td>185</td><td>5206</td><td>5215</td></tr><tr><td>13</td><td>1</td><td>40.33457</td><td>-12.2207</td><td>2023/06/12 06:49:16</td><td>40.33356</td><td>-12.22339</td><td>2023/06/12 10:05:38</td><td>40.334</td><td>-12.222</td><td>163.3524</td><td>196</td><td>5246</td><td>5261</td></tr><tr><td>14</td><td>1</td><td>40.55193</td><td>-12.65496</td><td>2023/06/12 13:38:31</td><td>40.55194</td><td>-12.65498</td><td>2023/06/12 16:44:02</td><td>40.552</td><td>-12.655</td><td>163.6328</td><td>186</td><td>5297</td><td>5307</td></tr><tr><td>15</td><td>1</td><td>40.78734</td><td>-13.09996</td><td>2023/06/12 21:51:48</td><td>40.78801</td><td>-13.10098</td><td>2023/06/13 01:20:50</td><td>40.788</td><td>-13.1</td><td>163.9836</td><td>209</td><td>5327</td><td>5338</td></tr><tr><td>16</td><td>1</td><td>41.08794</td><td>-13.49694</td><td>2023/06/13 05:07:25</td><td>41.08793</td><td>-13.49686</td><td>2023/06/13 08:24:15</td><td>41.088</td><td>-13.497</td><td>164.2818</td><td>197</td><td>5342</td><td>5347</td></tr><tr><td>17</td><td>1</td><td>41.38292</td><td>-13.88895</td><td>2023/06/13 12:26:16</td><td>41.38291</td><td>-13.88894</td><td>2023/06/13 15:31:56</td><td>41.383</td><td>-13.889</td><td>164.5827</td><td>186</td><td>5336</td><td>5346</td></tr><tr><td>18</td><td>1</td><td>41.68244</td><td>-14.27948</td><td>2023/06/13 19:47:50</td><td>41.68405</td><td>-14.281</td><td>2023/06/13 23:09:54</td><td>41.683</td><td>-14.28</td><td>164.895</td><td>202</td><td>5328</td><td>5338</td></tr><tr><td>19</td><td>1</td><td>41.98292</td><td>-14.67689</td><td>2023/06/14 02:53:53</td><td>41.98292</td><td>-14.67688</td><td>2023/06/14 06:00:37</td><td>41.983</td><td>-14.677</td><td>165.1856</td><td>187</td><td>5320</td><td>5329</td></tr><tr><td>20</td><td>1</td><td>42.2831</td><td>-15.06613</td><td>2023/06/14 10:02:50</td><td>42.28303</td><td>-15.06601</td><td>2023/06/14 13:24:47</td><td>42.283</td><td>-15.066</td><td>165.4888</td><td>202</td><td>5298</td><td>5306</td></tr><tr><td>21</td><td>1</td><td>42.57855</td><td>-15.46412</td><td>2023/06/14 18:25:24</td><td>42.58109</td><td>-15.4661</td><td>2023/06/14 21:27:11</td><td>42.58</td><td>-15.465</td><td>165.8308</td><td>182</td><td>4983</td><td>4991</td></tr><tr><td>22</td><td>1</td><td>42.88111</td><td>-15.85356</td><td>2023/06/15 01:05:47</td><td>42.88112</td><td>-15.85325</td><td>2023/06/15 03:34:09</td><td>42.881</td><td>-15.853</td><td>166.0972</td><td>148</td><td>4190</td><td>4200</td></tr></tbody></table>
<table><thead><tr><th>Station #</th><th>Cast #</th><th>Latitude begin</th><th>Longitude begin</th><th>Date begin</th><th>Latitude end</th><th>Longitude end</th><th>Date end</th><th>Latitude mean</th><th>Longitude mean</th><th>2023 day mean</th><th>Station durat. (min.)</th><th>CTD max depth</th><th>Bottom depth</th></tr></thead><tbody><tr><td>23</td><td>1</td><td>43.18057</td><td>-16.24574</td><td>2023/06/15 07:18:57</td><td>43.18202</td><td>-16.24689</td><td>2023/06/15 10:31:55</td><td>43.181</td><td>-16.246</td><td>166.3718</td><td>193</td><td>5117</td><td>5125</td></tr><tr><td>24</td><td>1</td><td>43.48023</td><td>-16.63559</td><td>2023/06/15 14:06:16</td><td>43.48022</td><td>-16.6356</td><td>2023/06/15 16:34:07</td><td>43.48</td><td>-16.636</td><td>166.639</td><td>148</td><td>4163</td><td>4173</td></tr><tr><td>25</td><td>1</td><td>43.78047</td><td>-17.02924</td><td>2023/06/15 21:41:35</td><td>43.78002</td><td>-17.03</td><td>2023/06/16 00:20:29</td><td>43.78</td><td>-17.03</td><td>166.9591</td><td>159</td><td>3999</td><td>4006</td></tr><tr><td>26</td><td>1</td><td>44.07928</td><td>-17.42313</td><td>2023/06/16 03:54:30</td><td>44.07923</td><td>-17.42281</td><td>2023/06/16 06:08:28</td><td>44.079</td><td>-17.423</td><td>167.2094</td><td>134</td><td>3782</td><td>3789</td></tr><tr><td>27</td><td>1</td><td>44.37704</td><td>-17.82174</td><td>2023/06/16 09:53:39</td><td>44.37703</td><td>-17.82174</td><td>2023/06/16 13:02:26</td><td>44.377</td><td>-17.822</td><td>167.4778</td><td>189</td><td>4930</td><td>4939</td></tr><tr><td>28</td><td>1</td><td>44.68003</td><td>-18.21453</td><td>2023/06/16 17:57:51</td><td>44.68004</td><td>-18.21451</td><td>2023/06/16 20:54:13</td><td>44.68</td><td>-18.215</td><td>167.8097</td><td>176</td><td>4838</td><td>4847</td></tr><tr><td>29</td><td>1</td><td>45.0352</td><td>-18.50559</td><td>2023/06/17 00:29:26</td><td>45.03521</td><td>-18.50557</td><td>2023/06/17 03:13:42</td><td>45.035</td><td>-18.506</td><td>168.0775</td><td>164</td><td>4672</td><td>4675</td></tr><tr><td>30</td><td>1</td><td>45.42317</td><td>-18.80074</td><td>2023/06/17 11:14:08</td><td>45.42317</td><td>-18.8009</td><td>2023/06/17 14:07:33</td><td>45.423</td><td>-18.801</td><td>168.5284</td><td>173</td><td>4563</td><td>4574</td></tr><tr><td>30</td><td>2</td><td>45.4236</td><td>-18.80092</td><td>2023/06/17 07:07:47</td><td>45.4236</td><td>-18.80092</td><td>2023/06/17 09:40:03</td><td>45.424</td><td>-18.801</td><td>168.3499</td><td>152</td><td>4419</td><td>4571</td></tr><tr><td>31</td><td>1</td><td>45.7958</td><td>-19.09068</td><td>2023/06/17 17:45:00</td><td>45.7958</td><td>-19.09066</td><td>2023/06/17 20:32:22</td><td>45.796</td><td>-19.091</td><td>168.7977</td><td>167</td><td>4512</td><td>4520</td></tr><tr><td>32</td><td>1</td><td>46.17531</td><td>-19.38078</td><td>2023/06/18 00:56:10</td><td>46.17532</td><td>-19.38083</td><td>2023/06/18 03:54:26</td><td>46.175</td><td>-19.381</td><td>169.1009</td><td>178</td><td>4597</td><td>4605</td></tr><tr><td>33</td><td>1</td><td>46.54448</td><td>-19.67029</td><td>2023/06/18 07:58:31</td><td>46.54398</td><td>-19.67311</td><td>2023/06/18 10:51:18</td><td>46.544</td><td>-19.672</td><td>169.3923</td><td>173</td><td>4520</td><td>4528</td></tr><tr><td>34</td><td>1</td><td>46.91693</td><td>-19.96856</td><td>2023/06/18 15:37:24</td><td>46.91695</td><td>-19.96855</td><td>2023/06/18 18:28:46</td><td>46.917</td><td>-19.969</td><td>169.7105</td><td>171</td><td>4491</td><td>4503</td></tr><tr><td>35</td><td>1</td><td>47.2876</td><td>-20.26376</td><td>2023/06/18 22:18:56</td><td>47.29005</td><td>-20.26293</td><td>2023/06/19 01:16:29</td><td>47.289</td><td>-20.263</td><td>169.9915</td><td>178</td><td>4504</td><td>4515</td></tr><tr><td>36</td><td>1</td><td>47.66618</td><td>-20.55279</td><td>2023/06/19 04:31:49</td><td>47.66618</td><td>-20.5528</td><td>2023/06/19 07:16:11</td><td>47.666</td><td>-20.553</td><td>170.2458</td><td>164</td><td>4344</td><td>4354</td></tr><tr><td>37</td><td>1</td><td>48.03797</td><td>-20.84799</td><td>2023/06/19 10:39:22</td><td>48.03796</td><td>-20.84796</td><td>2023/06/19 13:30:44</td><td>48.038</td><td>-20.848</td><td>170.5035</td><td>171</td><td>4446</td><td>4458</td></tr><tr><td>38</td><td>1</td><td>48.41274</td><td>-21.14052</td><td>2023/06/19 16:45:17</td><td>48.41275</td><td>-21.14049</td><td>2023/06/19 19:38:49</td><td>48.413</td><td>-21.141</td><td>170.7584</td><td>174</td><td>4326</td><td>4337</td></tr><tr><td>39</td><td>1</td><td>48.83544</td><td>-21.43043</td><td>2023/06/20 00:35:15</td><td>48.83597</td><td>-21.43081</td><td>2023/06/20 03:22:02</td><td>48.836</td><td>-21.431</td><td>171.0824</td><td>167</td><td>4321</td><td>4332</td></tr><tr><td>40</td><td>1</td><td>49.15795</td><td>-21.72378</td><td>2023/06/20 06:19:52</td><td>49.15795</td><td>-21.7238</td><td>2023/06/20 09:04:29</td><td>49.158</td><td>-21.724</td><td>171.321</td><td>165</td><td>4329</td><td>4342</td></tr><tr><td>41</td><td>1</td><td>49.54758</td><td>-22.0185</td><td>2023/06/20 12:20:09</td><td>49.54775</td><td>-22.01998</td><td>2023/06/20 15:04:49</td><td>49.548</td><td>-22.019</td><td>171.5712</td><td>165</td><td>4217</td><td>4228</td></tr><tr><td>42</td><td>1</td><td>49.90622</td><td>-22.30938</td><td>2023/06/20 19:30:17</td><td>49.90511</td><td>-22.31106</td><td>2023/06/20 22:06:47</td><td>49.906</td><td>-22.31</td><td>171.867</td><td>157</td><td>3990</td><td>4003</td></tr><tr><td>43</td><td>1</td><td>50.27674</td><td>-22.60328</td><td>2023/06/21 01:16:04</td><td>50.27693</td><td>-22.60366</td><td>2023/06/21 03:59:17</td><td>50.277</td><td>-22.603</td><td>172.1095</td><td>163</td><td>4120</td><td>4132</td></tr><tr><td>44</td><td>1</td><td>50.64018</td><td>-22.88552</td><td>2023/06/21 07:08:38</td><td>50.64019</td><td>-22.88553</td><td>2023/06/21 09:34:28</td><td>50.64</td><td>-22.886</td><td>172.3483</td><td>146</td><td>3737</td><td>3748</td></tr><tr><td>45</td><td>1</td><td>51.02908</td><td>-23.19045</td><td>2023/06/21 16:20:57</td><td>51.0291</td><td>-23.19046</td><td>2023/06/21 18:48:17</td><td>51.029</td><td>-23.19</td><td>172.7324</td><td>147</td><td>3922</td><td>3934</td></tr><tr><td>45</td><td>2</td><td>51.02838</td><td>-23.19055</td><td>2023/06/21 12:50:45</td><td>51.0281</td><td>-23.19012</td><td>2023/06/21 15:08:38</td><td>51.028</td><td>-23.19</td><td>172.5831</td><td>138</td><td>3850</td><td>3932</td></tr><tr><td>46</td><td>1</td><td>51.3994</td><td>-23.48023</td><td>2023/06/21 22:15:09</td><td>51.39925</td><td>-23.48025</td><td>2023/06/22 00:25:25</td><td>51.399</td><td>-23.48</td><td>172.9724</td><td>130</td><td>3268</td><td>3277</td></tr></tbody></table>
<table><thead><tr><th>Station #</th><th>Cast #</th><th>Latitude begin</th><th>Longitude begin</th><th>Date begin</th><th>Latitude end</th><th>Longitude end</th><th>Date end</th><th>Latitude mean</th><th>Longitude mean</th><th>2023 day mean</th><th>Station durat. (min.)</th><th>CTD max depth</th><th>Bottom depth</th></tr></thead><tbody><tr><td>47</td><td>1</td><td>51.77195</td><td>-23.7774</td><td>2023/06/22 03:43:37</td><td>51.77196</td><td>-23.77736</td><td>2023/06/22 06:13:11</td><td>51.772</td><td>-23.777</td><td>173.2072</td><td>150</td><td>3844</td><td>3854</td></tr><tr><td>48</td><td>1</td><td>52.14356</td><td>-24.07072</td><td>2023/06/22 09:32:12</td><td>52.14589</td><td>-24.07104</td><td>2023/06/22 12:02:30</td><td>52.145</td><td>-24.071</td><td>173.4495</td><td>150</td><td>3894</td><td>3904</td></tr><tr><td>49</td><td>1</td><td>52.5207</td><td>-24.36053</td><td>2023/06/22 15:12:34</td><td>52.52069</td><td>-24.36052</td><td>2023/06/22 17:27:23</td><td>52.521</td><td>-24.361</td><td>173.6805</td><td>135</td><td>3589</td><td>3599</td></tr><tr><td>50</td><td>1</td><td>52.89236</td><td>-24.66236</td><td>2023/06/22 21:07:03</td><td>52.89231</td><td>-24.66236</td><td>2023/06/22 23:27:27</td><td>52.892</td><td>-24.662</td><td>173.9286</td><td>140</td><td>3595</td><td>3605</td></tr><tr><td>51</td><td>1</td><td>53.26626</td><td>-24.95247</td><td>2023/06/23 02:42:22</td><td>53.26626</td><td>-24.95248</td><td>2023/06/23 04:54:31</td><td>53.266</td><td>-24.952</td><td>174.1586</td><td>132</td><td>3518</td><td>3528</td></tr><tr><td>52</td><td>1</td><td>53.63956</td><td>-25.23797</td><td>2023/06/23 08:09:18</td><td>53.63971</td><td>-25.23821</td><td>2023/06/23 10:32:32</td><td>53.64</td><td>-25.238</td><td>174.3895</td><td>143</td><td>3570</td><td>3579</td></tr><tr><td>53</td><td>1</td><td>54.01536</td><td>-25.5336</td><td>2023/06/23 23:46:10</td><td>54.01536</td><td>-25.5336</td><td>2023/06/24 01:45:10</td><td>54.015</td><td>-25.534</td><td>175.0317</td><td>119</td><td>3054</td><td>3062</td></tr><tr><td>54</td><td>1</td><td>54.38781</td><td>-25.82721</td><td>2023/06/24 05:03:02</td><td>54.38791</td><td>-25.82723</td><td>2023/06/24 07:02:25</td><td>54.388</td><td>-25.827</td><td>175.2519</td><td>119</td><td>3045</td><td>3055</td></tr><tr><td>55</td><td>1</td><td>54.76364</td><td>-26.12515</td><td>2023/06/24 11:13:01</td><td>54.76364</td><td>-26.12514</td><td>2023/06/24 13:39:41</td><td>54.764</td><td>-26.125</td><td>175.5183</td><td>147</td><td>3596</td><td>3608</td></tr><tr><td>56</td><td>1</td><td>55.14853</td><td>-26.40474</td><td>2023/06/25 20:33:02</td><td>55.14917</td><td>-26.40487</td><td>2023/06/25 23:00:22</td><td>55.149</td><td>-26.405</td><td>176.9074</td><td>147</td><td>3367</td><td>3379</td></tr><tr><td>57</td><td>1</td><td>55.50495</td><td>-26.70668</td><td>2023/06/26 05:09:02</td><td>55.50495</td><td>-26.70666</td><td>2023/06/26 07:14:10</td><td>55.505</td><td>-26.707</td><td>177.2581</td><td>125</td><td>3226</td><td>3235</td></tr><tr><td>58</td><td>1</td><td>55.88408</td><td>-26.99811</td><td>2023/06/26 10:10:57</td><td>55.88355</td><td>-26.99836</td><td>2023/06/26 12:04:02</td><td>55.884</td><td>-26.998</td><td>177.4635</td><td>113</td><td>2869</td><td>2881</td></tr><tr><td>59</td><td>1</td><td>56.25246</td><td>-27.29118</td><td>2023/06/26 15:15:44</td><td>56.25252</td><td>-27.2913</td><td>2023/06/26 17:04:47</td><td>56.252</td><td>-27.291</td><td>177.6738</td><td>109</td><td>2734</td><td>2742</td></tr><tr><td>60</td><td>1</td><td>56.6275</td><td>-27.57871</td><td>2023/06/26 20:27:18</td><td>56.62748</td><td>-27.57864</td><td>2023/06/26 22:18:57</td><td>56.627</td><td>-27.579</td><td>177.8911</td><td>112</td><td>2706</td><td>2717</td></tr><tr><td>61</td><td>1</td><td>57.00244</td><td>-27.87525</td><td>2023/06/27 01:26:42</td><td>57.00304</td><td>-27.87636</td><td>2023/06/27 03:18:51</td><td>57.003</td><td>-27.876</td><td>178.0991</td><td>112</td><td>2739</td><td>2751</td></tr><tr><td>62</td><td>1</td><td>57.37679</td><td>-28.1721</td><td>2023/06/27 06:27:47</td><td>57.37682</td><td>-28.17207</td><td>2023/06/27 08:11:51</td><td>57.377</td><td>-28.172</td><td>178.3054</td><td>104</td><td>2603</td><td>2613</td></tr><tr><td>62</td><td>2</td><td>57.37679</td><td>-28.17205</td><td>2023/06/27 09:15:19</td><td>57.37679</td><td>-28.17215</td><td>2023/06/27 10:48:32</td><td>57.377</td><td>-28.172</td><td>178.418</td><td>93</td><td>2602</td><td>2614</td></tr><tr><td>63</td><td>1</td><td>57.674</td><td>-28.72496</td><td>2023/06/27 14:12:40</td><td>57.67401</td><td>-28.72499</td><td>2023/06/27 15:53:33</td><td>57.674</td><td>-28.725</td><td>178.6272</td><td>101</td><td>2448</td><td>2458</td></tr><tr><td>64</td><td>1</td><td>57.96925</td><td>-29.27684</td><td>2023/06/27 19:43:45</td><td>57.96961</td><td>-29.27721</td><td>2023/06/27 21:12:43</td><td>57.969</td><td>-29.277</td><td>178.8529</td><td>89</td><td>2126</td><td>2136</td></tr><tr><td>65</td><td>1</td><td>58.20675</td><td>-29.72217</td><td>2023/06/28 00:46:36</td><td>58.20672</td><td>-29.72223</td><td>2023/06/28 02:22:34</td><td>58.207</td><td>-29.722</td><td>179.0657</td><td>96</td><td>2210</td><td>2222</td></tr><tr><td>66</td><td>1</td><td>58.4097</td><td>-30.10234</td><td>2023/06/28 05:44:54</td><td>58.40974</td><td>-30.1022</td><td>2023/06/28 07:12:15</td><td>58.41</td><td>-30.102</td><td>179.2698</td><td>87</td><td>2169</td><td>2178</td></tr><tr><td>67</td><td>1</td><td>58.536</td><td>-30.3553</td><td>2023/06/28 11:08:43</td><td>58.536</td><td>-30.35527</td><td>2023/06/28 12:12:39</td><td>58.536</td><td>-30.355</td><td>179.4866</td><td>64</td><td>1499</td><td>1508</td></tr><tr><td>68</td><td>1</td><td>58.72598</td><td>-30.69624</td><td>2023/06/29 06:15:08</td><td>58.72598</td><td>-30.69627</td><td>2023/06/29 07:14:44</td><td>58.726</td><td>-30.696</td><td>180.2812</td><td>60</td><td>1436</td><td>1447</td></tr><tr><td>69</td><td>1</td><td>58.84574</td><td>-31.26749</td><td>2023/07/01 01:35:03</td><td>58.84567</td><td>-31.26765</td><td>2023/07/01 02:37:25</td><td>58.846</td><td>-31.268</td><td>182.0877</td><td>62</td><td>1444</td><td>1455</td></tr><tr><td>70</td><td>1</td><td>58.91007</td><td>-31.90983</td><td>2023/07/01 05:43:17</td><td>58.9101</td><td>-31.90984</td><td>2023/07/01 06:53:23</td><td>58.91</td><td>-31.91</td><td>182.2627</td><td>70</td><td>1671</td><td>1681</td></tr><tr><td>71</td><td>1</td><td>58.97344</td><td>-32.55282</td><td>2023/07/01 10:00:22</td><td>58.97347</td><td>-32.5528</td><td>2023/07/01 11:22:05</td><td>58.973</td><td>-32.553</td><td>182.4453</td><td>82</td><td>1845</td><td>1850</td></tr></tbody></table>
<table><thead><tr><th>Station #</th><th>Cast #</th><th>Latitude begin</th><th>Longitude begin</th><th>Date begin</th><th>Latitude end</th><th>Longitude end</th><th>Date end</th><th>Latitude mean</th><th>Longitude mean</th><th>2023 day mean</th><th>Station durat. (min.)</th><th>CTD max depth</th><th>Bottom depth</th></tr></thead><tbody><tr><td>72</td><td>1</td><td>59.04106</td><td>-33.19231</td><td>2023/07/01 14:23:05</td><td>59.04105</td><td>-33.19372</td><td>2023/07/01 15:54:54</td><td>59.041</td><td>-33.193</td><td>182.6312</td><td>92</td><td>2273</td><td>2284</td></tr><tr><td>73</td><td>1</td><td>59.10237</td><td>-33.82426</td><td>2023/07/01 19:27:30</td><td>59.10238</td><td>-33.82429</td><td>2023/07/01 20:58:19</td><td>59.102</td><td>-33.824</td><td>182.8423</td><td>91</td><td>2266</td><td>2275</td></tr><tr><td>74</td><td>1</td><td>59.16362</td><td>-34.46759</td><td>2023/07/02 01:28:40</td><td>59.16388</td><td>-34.46899</td><td>2023/07/02 03:07:06</td><td>59.164</td><td>-34.468</td><td>183.0958</td><td>98</td><td>2476</td><td>2486</td></tr><tr><td>75</td><td>1</td><td>59.23275</td><td>-35.11732</td><td>2023/07/02 06:25:37</td><td>59.23275</td><td>-35.11733</td><td>2023/07/02 08:24:44</td><td>59.233</td><td>-35.117</td><td>183.3091</td><td>119</td><td>2979</td><td>2988</td></tr><tr><td>76</td><td>1</td><td>59.28476</td><td>-35.76022</td><td>2023/07/02 12:12:54</td><td>59.28491</td><td>-35.76142</td><td>2023/07/02 14:16:40</td><td>59.285</td><td>-35.761</td><td>183.5519</td><td>124</td><td>3091</td><td>3100</td></tr><tr><td>77</td><td>1</td><td>59.36245</td><td>-36.39497</td><td>2023/07/02 18:01:39</td><td>59.36241</td><td>-36.39508</td><td>2023/07/02 19:59:59</td><td>59.362</td><td>-36.395</td><td>183.7922</td><td>118</td><td>3087</td><td>3095</td></tr><tr><td>78</td><td>1</td><td>59.42747</td><td>-37.03614</td><td>2023/07/03 00:15:58</td><td>59.42794</td><td>-37.03855</td><td>2023/07/03 02:19:38</td><td>59.428</td><td>-37.037</td><td>184.054</td><td>124</td><td>3106</td><td>3116</td></tr><tr><td>79</td><td>1</td><td>59.49175</td><td>-37.67689</td><td>2023/07/03 05:31:53</td><td>59.49175</td><td>-37.67687</td><td>2023/07/03 07:35:27</td><td>59.492</td><td>-37.677</td><td>184.2734</td><td>124</td><td>3101</td><td>3112</td></tr><tr><td>80</td><td>1</td><td>59.55877</td><td>-38.30231</td><td>2023/07/03 11:13:52</td><td>59.55881</td><td>-38.30232</td><td>2023/07/03 13:13:57</td><td>59.559</td><td>-38.302</td><td>184.5097</td><td>120</td><td>3034</td><td>3042</td></tr><tr><td>81</td><td>1</td><td>59.6239</td><td>-38.9552</td><td>2023/07/03 16:22:52</td><td>59.62386</td><td>-38.95519</td><td>2023/07/03 18:13:54</td><td>59.624</td><td>-38.955</td><td>184.7211</td><td>111</td><td>2919</td><td>2927</td></tr><tr><td>82</td><td>1</td><td>59.68483</td><td>-39.59803</td><td>2023/07/03 22:40:42</td><td>59.68488</td><td>-39.59781</td><td>2023/07/04 00:32:44</td><td>59.685</td><td>-39.598</td><td>184.9838</td><td>112</td><td>2782</td><td>2793</td></tr><tr><td>83</td><td>1</td><td>59.72254</td><td>-40.25215</td><td>2023/07/04 07:03:00</td><td>59.72265</td><td>-40.25178</td><td>2023/07/04 08:49:13</td><td>59.723</td><td>-40.252</td><td>185.3306</td><td>106</td><td>2648</td><td>2658</td></tr><tr><td>83</td><td>2</td><td>59.72339</td><td>-40.25234</td><td>2023/07/04 04:26:01</td><td>59.72346</td><td>-40.2524</td><td>2023/07/04 05:57:13</td><td>59.723</td><td>-40.252</td><td>185.2164</td><td>91</td><td>2638</td><td>2657</td></tr><tr><td>84</td><td>1</td><td>59.75601</td><td>-40.8988</td><td>2023/07/04 12:02:15</td><td>59.75601</td><td>-40.89878</td><td>2023/07/04 13:33:27</td><td>59.756</td><td>-40.899</td><td>185.5332</td><td>91</td><td>2264</td><td>2274</td></tr><tr><td>85</td><td>1</td><td>59.77366</td><td>-41.29733</td><td>2023/07/04 15:46:25</td><td>59.77358</td><td>-41.29736</td><td>2023/07/04 17:08:07</td><td>59.774</td><td>-41.297</td><td>185.6856</td><td>82</td><td>2028</td><td>2037</td></tr><tr><td>86</td><td>1</td><td>59.79358</td><td>-41.7311</td><td>2023/07/04 19:20:14</td><td>59.79359</td><td>-41.7311</td><td>2023/07/04 20:35:31</td><td>59.794</td><td>-41.731</td><td>185.8319</td><td>75</td><td>1838</td><td>1845</td></tr><tr><td>87</td><td>1</td><td>59.80025</td><td>-42.00376</td><td>2023/07/04 23:46:49</td><td>59.80026</td><td>-42.00374</td><td>2023/07/05 00:56:14</td><td>59.8</td><td>-42.004</td><td>186.0149</td><td>69</td><td>1709</td><td>1722</td></tr><tr><td>88</td><td>1</td><td>59.80846</td><td>-42.23689</td><td>2023/07/05 02:24:13</td><td>59.80883</td><td>-42.23576</td><td>2023/07/05 03:18:24</td><td>59.809</td><td>-42.236</td><td>186.119</td><td>54</td><td>1190</td><td>1204</td></tr><tr><td>89</td><td>1</td><td>59.81531</td><td>-42.27582</td><td>2023/07/05 04:47:11</td><td>59.81529</td><td>-42.27582</td><td>2023/07/05 05:20:33</td><td>59.815</td><td>-42.276</td><td>186.211</td><td>33</td><td>884</td><td>900</td></tr><tr><td>90</td><td>1</td><td>59.81669</td><td>-42.31699</td><td>2023/07/05 08:12:16</td><td>59.8167</td><td>-42.31697</td><td>2023/07/05 08:37:45</td><td>59.817</td><td>-42.317</td><td>186.3507</td><td>25</td><td>505</td><td>522</td></tr><tr><td>91</td><td>1</td><td>59.82174</td><td>-42.39524</td><td>2023/07/05 10:10:39</td><td>59.82173</td><td>-42.39524</td><td>2023/07/05 10:25:27</td><td>59.822</td><td>-42.395</td><td>186.4292</td><td>15</td><td>296</td><td>308</td></tr><tr><td>92</td><td>1</td><td>59.83197</td><td>-42.51577</td><td>2023/07/05 12:24:52</td><td>59.83174</td><td>-42.51684</td><td>2023/07/05 12:39:14</td><td>59.832</td><td>-42.516</td><td>186.5223</td><td>14</td><td>229</td><td>236</td></tr><tr><td>93</td><td>1</td><td>59.91267</td><td>-43.07365</td><td>2023/07/05 16:24:45</td><td>59.91267</td><td>-43.07367</td><td>2023/07/05 16:36:33</td><td>59.913</td><td>-43.074</td><td>186.688</td><td>12</td><td>162</td><td>171</td></tr><tr><td>94</td><td>1</td><td>59.89613</td><td>-42.95835</td><td>2023/07/05 18:47:49</td><td>59.89612</td><td>-42.95834</td><td>2023/07/05 19:03:05</td><td>59.896</td><td>-42.958</td><td>186.7885</td><td>15</td><td>160</td><td>167</td></tr><tr><td>95</td><td>1</td><td>59.87848</td><td>-42.85026</td><td>2023/07/05 20:29:49</td><td>59.8785</td><td>-42.85016</td><td>2023/07/05 20:43:12</td><td>59.87849</td><td>-42.85021</td><td>186.8587</td><td>13</td><td>177</td><td>188</td></tr><tr><td>96</td><td>1</td><td>59.86246</td><td>-42.74517</td><td>2023/07/05 21:50:55</td><td>59.8625</td><td>-42.74517</td><td>2023/07/05 22:04:45</td><td>59.86248</td><td>-42.74517</td><td>186.9152</td><td>14</td><td>171</td><td>183</td></tr></tbody></table>
<table><thead><tr><th>Station #</th><th>Cast #</th><th>Latitude begin</th><th>Longitude begin</th><th>Date begin</th><th>Latitude end</th><th>Longitude end</th><th>Date end</th><th>Latitude mean</th><th>Longitude mean</th><th>2023 day mean</th><th>Station durat. (min.)</th><th>CTD max depth</th><th>Bottom depth</th></tr></thead><tbody><tr><td>97</td><td>1</td><td>59.85346</td><td>-42.66609</td><td>2023/07/05 22:53:38</td><td>59.8533</td><td>-42.6667</td><td>2023/07/05 23:04:24</td><td>59.85338</td><td>-42.666395</td><td>186.9577</td><td>11</td><td>177</td><td>189</td></tr><tr><td>98</td><td>1</td><td>59.84311</td><td>-42.59139</td><td>2023/07/05 23:55:13</td><td>59.84317</td><td>-42.59133</td><td>2023/07/06 00:08:55</td><td>59.84314</td><td>-42.59136</td><td>187.0014</td><td>14</td><td>190</td><td>201</td></tr><tr><td>110</td><td>1</td><td>53.42261</td><td>-25.63961</td><td>2023/06/23 16:18:43</td><td>53.42259</td><td>-25.63965</td><td>2023/06/23 18:20:15</td><td>53.423</td><td>-25.64</td><td>174.7219</td><td>122</td><td>3645</td><td>3656</td></tr><tr><td>111</td><td>1</td><td>60.98646</td><td>-42.43172</td><td>2023/07/07 06:20:42</td><td>60.98647</td><td>-42.4317</td><td>2023/07/07 06:34:40</td><td>60.98646</td><td>-42.43171</td><td>188.2692</td><td>14</td><td>150</td><td>157</td></tr><tr><td>112</td><td>1</td><td>60.92519</td><td>-41.86817</td><td>2023/07/07 09:14:32</td><td>60.92519</td><td>-41.86825</td><td>2023/07/07 09:28:10</td><td>60.92519</td><td>-41.8682</td><td>188.3898</td><td>14</td><td>156</td><td>164</td></tr><tr><td>113</td><td>1</td><td>60.89295</td><td>-41.61067</td><td>2023/07/07 11:15:00</td><td>60.89296</td><td>-41.61067</td><td>2023/07/07 11:50:49</td><td>60.893</td><td>-41.611</td><td>188.4812</td><td>36</td><td>831</td><td>846</td></tr><tr><td>114</td><td>1</td><td>60.86802</td><td>-41.39585</td><td>2023/07/07 13:59:52</td><td>60.86805</td><td>-41.39584</td><td>2023/07/07 15:22:05</td><td>60.868</td><td>-41.396</td><td>188.6118</td><td>82</td><td>1766</td><td>1777</td></tr><tr><td>116</td><td>1</td><td>64.46191</td><td>-37.88953</td><td>2023/07/09 04:41:37</td><td>64.46191</td><td>-37.88953</td><td>2023/07/09 05:13:23</td><td>64.462</td><td>-37.89</td><td>190.2066</td><td>32</td><td>784</td><td>795</td></tr><tr><td>117</td><td>1</td><td>64.1114</td><td>-36.82104</td><td>2023/07/09 10:59:02</td><td>64.1114</td><td>-36.82104</td><td>2023/07/09 11:22:01</td><td>64.1114</td><td>-36.82104</td><td>190.4656</td><td>23</td><td>398</td><td>405</td></tr><tr><td>120</td><td>1</td><td>63.90765</td><td>-36.18986</td><td>2023/07/09 14:23:43</td><td>63.90772</td><td>-36.18963</td><td>2023/07/09 15:31:15</td><td>63.908</td><td>-36.19</td><td>190.6233</td><td>68</td><td>1455</td><td>1466</td></tr><tr><td>121</td><td>1</td><td>63.74367</td><td>-35.66833</td><td>2023/07/09 17:58:16</td><td>63.74365</td><td>-35.66832</td><td>2023/07/09 19:22:04</td><td>63.744</td><td>-35.668</td><td>190.7779</td><td>84</td><td>2145</td><td>2155</td></tr><tr><td>122</td><td>1</td><td>63.21645</td><td>-34.03577</td><td>2023/07/10 01:33:46</td><td>63.21645</td><td>-34.03593</td><td>2023/07/10 03:23:17</td><td>63.216</td><td>-34.036</td><td>191.1031</td><td>110</td><td>2756</td><td>2766</td></tr><tr><td>123</td><td>1</td><td>62.63561</td><td>-32.25963</td><td>2023/07/10 10:23:55</td><td>62.63562</td><td>-32.25963</td><td>2023/07/10 12:20:04</td><td>62.636</td><td>-32.26</td><td>191.4736</td><td>116</td><td>2904</td><td>2916</td></tr><tr><td>124</td><td>1</td><td>62.03589</td><td>-30.51097</td><td>2023/07/10 19:04:48</td><td>62.03594</td><td>-30.51121</td><td>2023/07/10 20:30:04</td><td>62.036</td><td>-30.511</td><td>191.8246</td><td>85</td><td>2135</td><td>2144</td></tr><tr><td>125</td><td>1</td><td>61.46724</td><td>-28.80203</td><td>2023/07/11 03:07:46</td><td>61.46725</td><td>-28.80203</td><td>2023/07/11 04:14:33</td><td>61.467</td><td>-28.802</td><td>192.1536</td><td>67</td><td>1598</td><td>1609</td></tr><tr><td>126</td><td>1</td><td>61.14494</td><td>-27.97139</td><td>2023/07/11 08:52:40</td><td>61.14494</td><td>-27.97137</td><td>2023/07/11 09:35:49</td><td>61.145</td><td>-27.971</td><td>192.3849</td><td>43</td><td>954</td><td>964</td></tr></tbody></table>
## 1.5 Overview of the operations and main technical problems during the cruise

<figure><img src="image_8.png" /><figcaption>Figure 6: chronogram of the operations</figcaption></figure>
Major incidents during the cruise:

* During the test station, an issue appeared on the CTD rosette motor and one of them was changed

* During the Ria's stations, the first 10 stations of the OVIDE section, and the genomic station number 100 (renamed 10 cast 2), the acquisition frequency of the probe was of 1Hz instead of 24Hz. To compensate this issue, a post processing by interpolation was realized to obtain 24Hz files.

* For station 32, a jelly fish was stuck in the secondary circuit of CTD sensors and disturbed the data.

* At the station 68, a communication issue with the rosette motor appeared. The cable between the 2 motors has been changed.

* At the beginning of the station 69, a problem of communication with the probe appeared. UTM crew made a new connection between the cable of the ship and the probe.

* The cruise was interrupted twice for the bad weather: from 24th to 26th and from 29th to 30th of June.

* We discovered that the position sent to the CTD acquisition PC was not the correct one and showed a drift in latitude and longitude as we moved northwestward (up to 8 Nm). All the positions were corrected based on the reprocessed navigation data. Note that SADCP data were not affected by this bug, and that the position at the bridge and on the screens (other than the one of CTD computer) was correct.

All operations are summarized in Figure 6 as a function of time, with station number on the Y-axis.
# 2 General information about data acquisition

## 2.1 Equipment

For hydrology acquisition, we used our LOPS frame with 28 bottles of 8 liters and a SBE911+ CTD. The frame is also equipped with 2 LADCP, electronic reversing sensors and altimeter.

<figure><img src="image_9.png" /><figcaption>Figure 7: LOPS CTD rosette</figcaption></figure>

(bottles 3 to 16 on the upper level)
(bottles 17 to 30 on the lower level)

<figure><img src="image_10.png" /><figcaption>Figure 8: Upper LADCP on CTD frame</figcaption></figure>

The same Seabird 911+ CTD probe (s/n. 813) was used throughout the cruise. It was equipped with two sets of T, C, and O2 sensors. The frame was also equipped with 2 LADCP (down-looking 150 kHz and up-looking 300 kHz), 4 SIS reversing sensors (2 for Pressure measurements and 2 for Temperature measurements) and a Valeport altimeter (500 kHz) working at a frequency significantly different than the ADCP's. The LADCPs take the place of bottles 1, 2, 31 and 32.

The CTD sensors used:

<table><thead><tr><td></td><td>Primary sensors</td><td>Secondary sensors</td></tr></thead><tbody><tr><td>Temperature (SBE3+)</td><td>s/n 2911</td><td>s/n 4594</td></tr><tr><td>Conductivity (SBE4c)</td><td>s/n 3194</td><td>s/n 3166</td></tr><tr><td>Oxygen (SBE43)</td><td>s/n 1402</td><td>s/n 526</td></tr></tbody></table>
Electronics mounted on the LOPS frame:

<table><thead><tr><th></th><th>top</th><th>bottom</th></tr></thead><tbody><tr><td>PASH 6000 Rosette</td><td>s/n 462</td><td>s/n 460</td></tr><tr><td>ADCP</td><td>Upward-looking:<br>s/n 2002 RDI 300 kHz<br>WorkHorse (slave)</td><td>Downward-looking:<br>s/n 23909 RDI 150 kHz<br>WorkHorse (master) and after<br>the station n°9, s/n 24609 RDI<br>150 kHz WorkHorse</td></tr><tr><td>IXSEA Pinger</td><td></td><td>s/n 530</td></tr><tr><td>Valeport altimeter</td><td></td><td>s/n 59678</td></tr></tbody></table>

SIS Reversing sensors:

<table><thead><tr><th></th><th>Bottle 3</th><th>Bottle 5</th></tr></thead><tbody><tr><td>SIS pressure meter RPM 6000X</td><td>s/n 6664</td><td>s/n 6665</td></tr><tr><td>SIS thermometer RTM4002X</td><td>s/n 1752 and 1750 after<br>station 75</td><td>s/n 1751</td></tr></tbody></table>

## 2.2 CTD Acquisition Protocol

The control of the CTD is carried out by 2 people: one from UTM team and one from IFREMER team.

The CTD casts start with a round trip at a depth of 30 m to remove the air bubbles in the 2 circuits of the sensors. From station 1 to 19, the operators start the data acquisition when the CTD is back near the surface; for the other stations, the acquisition started before, including the surface soak. The CTD downcast is run from the surface down to a distance of about 10 meters above the bottom. The final bottom approach is performed using the altimeter, as soon as it has 'latched' the bottom at a distance of about 90 m. During the upcast, the frame is stopped at predefined levels of closure of the 28 sampling bottles. A delay of 30 seconds at each level is respected before closing the bottle(s) and the CTD data are recorded during 8 seconds to generate the bottles files. The electro-mechanical cable is unwound and wound at a speed of 1 m/s.

The measurements of the probe are monitored on a screen with Seasave v7 software. This system allows the real time visualization of the different parameters measured and calculated on the profiles, while controlling the quality of the signal transmitted by the probe. All of the data transmitted by the probe, at the rate of 24 cycles per second, are saved on a disk.

## 2.3 Sampling protocol

As soon as the rosette is on board, the samples are taken from each bottle for the numerous analyses performed on board, in the order recommended by the WOCE instructions: dissolved gas ($N_2O/CH_4$), alkalinity, carbon isotopes ($\delta^{13}C$), alkalinity, nutrients (silicate, phosphate, nitrate and nitrite), salinity, seawater isotopes ($\delta^{18}O$, $\delta D$) and DOC. The bottles are sampled from the deepest to the shallowest levels (from bottle 3 to 30).

The salinity and oxygen samples will be used to adjust the salinity and dissolved oxygen CTD profiles. For a lot of casts, two bottles are fired at the same pressure level to have replicates. It improves the adjustment and helps to quantify the quality of the measurements.

The details of the protocols are described in appendix E and F
3 Chronological steps applied to the CTD-O2 data

3.1 Pre-cruise activity

<figure><img src="image_11.png" /></figure>

3.2 During the cruise

<figure><img src="image_12.png" /></figure>

3.3 Post-cruise treatment

<figure><img src="image_13.png" /></figure>
# 4 CTD probe measurements

Before each cruise, the CTD was adjusted by Seabird for the parameters Pressure, Temperature, Conductivity and Oxygen. New coefficients are calculated for each sensor.

Independently, before and after each cruise our CTD was calibrated in the Ifremer Metrology laboratory which is under COFRAC accreditation for Pressure and Temperature calibration. For this cruise and because the metrology lab had issues with the reference equipment, only the pre-cruise calibration in temperature has been done.

## 4.1 Pressure measurements

The SBE9+ probe is equipped with a Paroscientific digiquartz pressure sensor which characteristics are:

Resolution: 0.001 %, i.e. 0.1 psi or 0.07 dbar

Accuracy: 0.015 % of the full scale (10000 psi), or in our case ± 1.5 psi or ± 1.0 dbar

The sensor was calibrated by Seabird 28th of November 2022 before the cruise to have new coefficients (Refer to appendix A).

On the CTD, we had only one pressure sensor, so we followed the response of the CTD pressure sensor during the cruise using two reversing pressure meter sensor (SIS RPM 6000X) mounted on bottles 3 and 5. These sensors take the measurements when the bottle closes. We compared the value of the CTD sensor and SIS sensor to detect any drift.

The SIS pressure meters have not been calibrated since we bought them, so we follow relative relation (Figure 9). Due to mechanical problems, the pressure meters did not give data at all stations. But we have enough to assess that no drift was observed in the CTD pressure sensor, so the pressure measured by the SBE 911 was not corrected.

<figure><img src="image_14.png" /><figcaption>Figure 9: Monitoring of the pressure sensor drift during the cruise</figcaption></figure>
## 4.2 Temperature measurements

Our probe is equipped with two sets of temperature sensors Seabird SBE3 which characteristics are:

Resolution: 0.0003°C

Accuracy: 0.0010°C

The sensors were calibrated by Seabird the 4th of November 2022 before the cruise to have new coefficients (Refer to appendix B).

### 4.2.1 Calibration of the temperature sensors at Ifremer metrology laboratory

The temperature sensors are fully immersed in a thermostatic seawater bath HART model 7BATH-045 which temperature stability is ±0.001°C. The reference temperature of the bath is provided by a Rosemount platinum resistance 25Ω thermometer, placed in close proximity to the sensors. This reference thermometer is periodically calibrated at two fixed point of the EIT90: the triple point of water and the Gallium fusion point. The traceability of the measurements to the SI (International system) is sure.

<figure><img src="image_15.png" /><figcaption>Figure 10: pre-cruise calibration of the primary temperature sensor n°2911</figcaption></figure>

<figure><img src="image_16.png" /><figcaption>Figure 11: pre-cruise calibration of the secondary temperature sensor n°4594</figcaption></figure>

The uncertainty on the temperature corrections obtained in the laboratory conditions is $U = 0.014°C$ (with $k=2$)

### 4.2.2 Correction of the temperature measurements on the CTD profiles

The uncertainty on the correction compared with the correction itself is important so no correction on the temperature measurements was applied but the final uncertainty on the temperature measurements (in the conditions of the laboratory) needs to take in account this correction by add it linearly. The maximal calibration uncertainty obtained is 0.015°C.

**Remark:** we have to keep in mind that the major component of this budget uncertainty comes from the bath and its homogeneity. The standard deviation of the measurements during the calibration is around 0.0004°C and the repeatability is around 0.0001°C.

### 4.2.3 Validation of the CTD temperature measurements

During the cruise, we followed the response of the CTD temperature sensor compared with the reversing thermometers (SIS RTM 4002X) on bottle 3 and bottle 5. We compared the value of the CTD
sensor and SIS sensor at the bottom to detect any drift. Like for the pressure measurements, some issues occurred during the cruise on these thermometers and a lot of their data couldn't be used.

<figure><img src="image_17.png" /><figcaption>Figure 12: Monitoring of the temperature sensor drift during the cruise</figcaption></figure>

Conclusion: no correction was applied to temperature measurements.
## 4.3 Conductivity measurements

Our probe is equipped with two sets of conductivity sensors Seabird SBE4c which characteristics are:

Resolution: 0.0004mS/cm

Accuracy: 0.0030mS/cm

The sensors were calibrated by Seabird the 27th of October 2022 before the cruise to have new coefficients (Refer to appendix C).

During the cruise, salinity samples were taken at each station to adjust the conductivity measurements of the probe.

## 4.4 Oxygen measurements

Two sets of oxygen sensors Seabird SBE43 are also connected to the probe which characteristics are:

Resolution: No information

Accuracy: 2% of saturation

The SBE43 sensors provide data in Volt. To convert them in ml/l, Seabird applies this formula:

$$ \text{Oxygen} = [\text{Soc} \times (V + V_{\text{offset}} + \text{tau} \times \frac{dV}{d_t})] \times \text{Ox}_{\text{sol}} \times (1 + A \times T + B \times T^2 + C \times T^3) \times e^{(E \times \frac{P}{K})} \qquad \varphi $$

Where:

* V = Oxygen in volt

* $\frac{dV}{dt}$ = derivatives (volt/second)

* T = Temperature in °C

* S = Salinity

* P = Pressure in dbar

* K = Temperature in kelvin (°K = °C + 273.15)

* tau = Time constant

* Ox\_sol = Oxygen solubility

* Soc, Voffset, A, B, C, E: sensor calibration coefficients

In practice, the term associated with tau is neglected because it adds noise when the profile is homogeneous vertically (see Application note n° 64; Nov 2008). The equation becomes:

$$ \text{Oxygen} = [\text{Soc} \times (V + V_{\text{offset}})] \times \varphi $$

The sensors were adjusted by Seabird the 23th of February 2023 before the cruise to have new coefficients (Refer to appendix D).

During the cruise, oxygen samples were taken at each station to adjust the dissolved oxygen measurements of the probe.
# 5 Salinity and oxygen samples analysis

During the cruise, 2406 salinity samples and 2338 oxygen samples were analyzed. Some of them are replicates of two bottles at the same sampling level.

## 5.1 Equipment

All the salinity and dissolved oxygen samples are analyzed on board, during the cruise, in the LOPS chemical analysis container, which has Metrohm Ti Touch 916 titrator and Guildline Portasal salinometers. Air conditioning allows regulation of the room temperature (20 °C at ± 1 °C).

As soon as the collection of the cast is finished, the samples are placed in the analysis container. The samples (specially the salinity samples) are analyzed 20 to 30 hours after collection to allow them to achieve a thermal equilibrium.

<figure><img src="image_18.png" /><figcaption>Figure 13: samples boxes</figcaption></figure>

<figure><img src="image_19.png" /><figcaption>Figure 14: salinity sample</figcaption></figure>

<figure><img src="image_20.png" /><figcaption>Figure 15: oxygen sample</figcaption></figure>

<figure><img src="image_21.png" /><figcaption>Figure 16: Metrohm Ti Touch 916 oxygen analyzer with a platinum titrode, a 20 ml burette to deliver the sodium thiosulfate and a 5ml burette to deliver the potassium iodate</figcaption></figure>

<figure><img src="image_22.png" /><figcaption>Figure 17: Guildline portasal 8410A salinometer</figcaption></figure>
The daily standardization of the measuring instruments (salinometers and tritrinos) was performed by Caroline LE BIHAN, all salinity analyses were performed by Michel HAMON, and oxygen analyses by Philippe LE BOT.

## 5.2 Salinity analysis

### 5.2.1 General protocol

The salinity of the samples is determined according to the equation PSS 78 (UNESCO 1981). Throughout the cruise, the temperature of the salinometer is fixed at 21°C.

For each sample, three successive rinses of the cell are performed before making three readings separated each time by a rinse.

The salinometer Guildline was connected to a PC and all the analysis were saved directly on computer with a homemade software in python 'easysal'

All salinity measurements taken during the OVIDE cruise were performed on the same Portasal salinometer (s/n: 71420 id « D »).

This salinometer was standardized using batches of standard seawater bottles (IAPSO Standard Seawater): batch P164 (Salinity = 34.994), P165 (Salinity = 34.994) and P166 (Salinity = 34.995). The standardization was verified every morning and after analysis of two casts (56 samples).

Dates of salinometer adjustment: 11th and 20th of June

### 5.2.2 Replicates in salinity

The replicates help to quantify the quality of the chemical data.

<figure><img src="image_23.png" /><figcaption>Figure 18: validated salinity replicates</figcaption></figure>

<figure><img src="image_24.png" /><figcaption>Figure 19: histogram of the validated salinity replicates</figcaption></figure>

The standard deviation of salinity replicates is 0.001, used to quantify "chemical salinity error" (section 6.4.3).
## 5.3 Oxygen analysis

### 5.3.1 General protocol

The operating conditions and the analysis method (Winkler titration) comply to the recommendations of WOCE (WOCE Operations Manual, 1991).

The details of the protocol are described in appendix G

After acidification in the sampling bottle, the liberated iodine is dosed with a solution of sodium thiosulfate which normality is about 0.02 N. Its normality is determined daily, before the start of the analysis series, by comparison to a potassium iodate solution, which normality is 0.020015.

The Ti-Touch titrator (with DOSINO1 and control liquid handling Id20-2 et Id5-2) was connected to a PC and all the analysis were saved directly on computer with a homemade software in python 'easytitrino'.

### 5.3.2 Replicates in oxygen

The replicates help to quantify the quality of the chemical data.

<figure><img src="image_25.png" /><figcaption>Figure 20: validated oxygen replicates</figcaption></figure>

<figure><img src="image_26.png" /><figcaption>Figure 21: histogram of the validated oxygen replicates</figcaption></figure>

The standard deviation of dissolved oxygen replicates is 0.018 ml/l, used to quantify "chemical oxygen error" (section 6.4.3).
# 6 Post-cruise treatment

During this part of data treatment, all the steps given in paragraph 3.3 will be described more precisely.

## 6.1 Data preparation

To clean the measurements, we use the hydro_nett software. Hydro_nett is applied to « bo23st*T1.cnv » files, obtained after decoding the probe measurements by datcnv (part of the SbeDataProcessing seabird software).

### 6.1.1 Data cleaning with Hydro_nett

The software is first used to correct aberrant pressure measurements in the .cnv files. Then, all measurements are cleaned using thresholds and median deviation tests, parametrized as seen in Figure 22.

<figure><img src="image_27.png" /><figcaption>Figure 22: Hydro_nett options used for BOCATS23</figcaption></figure>
### 6.1.2 Correction of the hysteresis on O2 measurements

The principle of hysteresis correction on the SBE 43 sensor from Seabird is described in the application note SBE 64-3 and was coded in Matlab.

The hysteresis correction depends on three coefficients: H1, H2 and H3. The default values of these coefficients are provided by Seabird.

$$ 
\begin{aligned}
H1 &= -0.033 \\
H2 &= 5000 \\
H3 &= 1450
\end{aligned}
 $$

Those coefficients were used for this cruise and the resulting files are called `bo23st*T1 trait_hyst.cnv`.

### 6.1.3 Bottle file

After cleaning and correcting the pressure, temperature, conductivity and dissolved oxygen profiles from the probe (referred to as CTDO2 profiles in the following), we create a new bottle file with CTDO2 values corrected. For each station, the name of the file is « `bo23st***T1corr.btl` ».

## 6.2 Seabird treatment

Seabird developed a bunch of routines in its Seasoft V2 (SBEDataPostprocessing) software suite in order to improve the recorded probe measurements. The sequence of programs chosen by the LOPS is the result of a study performed on the 2008 CTD cruises (see C. Kermabon, M. Arhan, "Validation et Réduction des données de la sonde 9+", June 2008). The Seabird programs are applied after `Hydro_nett` and hysteresis correction, with the following parameters:

<figure><img src="image_28.png" /></figure>

* **Filter:** filters on pressure measurements

* Low pass filter A: 0.03s

* Low pass filter B: 0.15s

* **Alignctd:** applies a delay on the primary and secondary oxygen measurements

* Delay applied: 4s
* **Cell TM:** takes into account the effect of the thermal mass of the conductivity cell using a recursive filter

Thermal anomaly amplitude (alpha): 0.03

Thermal anomaly time constant (1/beta): 7

* **LoopEdit:** flags the cycles compared to the speed of the probe.

Minimum velocity type: fixed minimum velocity

Minimum CTD velocity (m/s): 0

Remove surface soak: Selected when acquisition begins before soaking

Exclude scans marked bad: selected

* **Derive:** new calculation of O2 ml/l and salinity.

* **BinAvg:** average the data for 1dbar and separate downcast and upcast (not used for calibration)

## 6.3 Data adjustment

Hydro\_cal software, part of the Cadhyac software suite, is used to adjust the data of the probe by following different steps:

<figure><img src="image_29.png" /></figure>

At this point, it is necessary to choose between primary and secondary sensors since corrections will most probably be different. For this cruise, primary sensors were chosen for their overall better quality.
### 6.3.1 Concatenation of the bottle files and creation of a chemical file

The goal of this part is to generate a global file for all the cruise from the bottle files of each station (obtained in the 6.1.3 paragraph) including both CTD and chemical data.

The information in this file is:

- Number of the station

- number of the sampling bottle

- probe's data average at the closure of the bottle (pressure (corrected if it was necessary), primary temperature (corrected if it was necessary), primary conductivity, primary salinity, secondary temperature (corrected if it was necessary), secondary conductivity, secondary salinity, primary oxygen measurement in Volt, secondary oxygen measurement in Volt, primary oxygen data in ml/l and secondary oxygen data in ml/l

- salinity of the sample

- oxygen and temperature of the sample

This "bottle file" is used in the following steps.

### 6.3.2 Determination of the correction in Conductivity/Salinity

#### Operating mode

The calibration procedure for the conductivity measurements given by the sensors (COs), written according to the recommendations of the GO-SHIP group, first involves the conversion of the chemical salinity into chemical conductivity (COH).

Then, the different corrections to be applied successively are calculated to minimize the differences $ΔC = COH - COs$ (shown in Figure 23):

* Correction as a function of time to take into account a potential slow drift of the conductivity sensor.

$$Ccorrsta = Csonde + A2*station^2 + A1*station + A0.$$

* Correction as a function of the conductivity.

$$Ccorrcond = Ccorrsta + A2*Ccorrsta^2 + A1*Ccorrsta + A0$$

* Correction as a function of the pressure.

$$Ccorr = Ccorrcond + A5*P^5 + A4*P^4 + ... + A1*P + A0$$

The selected coefficients result from successive iterations on the considered group of samples, removing outsiders at each iteration. The process is stopped when no additional sample is removed at the end of the current iteration. It follows that, at the end of the last iteration, all the differences $ΔC$ are lower than the $2.8 * σ$ ($σ$ : standard deviation of the differences) for the samples used in the calculation process.
The conductivity differences between conductivity bottle and raw conductivity sensor without any correction or offset is plotted in different plots in function of conductivity, time and pressure.

<figure><img src="image_30.png" /><figcaption>Figure 23: Conductivity raw differences</figcaption></figure>

a) as a function of the conductivity,

b) as a function of the time (as the casts progress),

c) as a function of the pressure of the sampling level.

By analyzing these raw results, we applied the different corrections described in paragraph « Operating mode » successively to all the casts together:

* No correction for a potential drift of the sensor

* A degree 1 polynomial correction as a function of the conductivity

* A degree 1 polynomial correction as a function of the pressure.
Figure 24 shows the result of the adjustment of the conductivity sensor with the application of corrections. All the dots are plotted (blue dots kept as validated samples, red dots rejected) and around 85% of the samples have been kept for the determination of the conductivity correction.

Polynomial corrections applied:

<table><caption>Table 1: Conductivity polynomial corrections applied</caption><thead><tr><th rowspan="2"></th><th colspan="2">Drift coeff</th><th colspan="2">Conductivity coeff</th><th colspan="2">Pressure coeff</th></tr><tr><th>A<sub>1</sub></th><th>A<sub>0</sub></th><th>A<sub>1</sub></th><th>A<sub>0</sub></th><th>A<sub>1</sub></th><th>A<sub>0</sub></th></tr></thead><tbody><tr><td>Station 1-126</td><td>0</td><td>0</td><td>-0.184019</td><td>4.17919</td><td>2.8157E-4</td><td>-0.381161</td></tr></tbody></table>

<figure><img src="image_31.png" /><figcaption>Figure 24: Final conductivity calibration</figcaption></figure>

a) as a function of the conductivity,

b) as a function of the time (as the casts progress),

c) as a function of the pressure of the sampling level.
The differences between the conductivity/salinity of the validated samples and the CTD conductivity/salinity at the sampling level are categorized in these histograms:

<figure><img src="image_32.png" /><figcaption>Figure 25: histogram of conductivity differences
a) for all the validated samples
b) for the validated samples at a pressure greater than 980dbar</figcaption></figure>

<figure><img src="image_33.png" /><figcaption>Figure 26: histogram of salinity differences
a) for all the validated samples
b) for the validated samples at a pressure greater than 980dbar</figcaption></figure>

The histograms confirm that the distribution of the differences is satisfactory and confirm the quality of the adjustment.

In 60 % of cases, the differences in conductivity are lower than ± 0.001 mS/cm, while in 100.0 %, they are less than ± 0.003 mS/cm. The standard deviation in conductivity is around 0.001 mS/cm.

### 6.3.3 Application of the correction

The polynomial correction in conductivity calculated above is apply to all the casts of the cruise and new files are created: bo23st***corr_PTC.cnv

To check the data, the theta-S diagram is plotted for 2 stations visited biennially since 2010 (Figure 27), with a zoom on deep water for evaluating the quality and consistency of the data. Station 13 is located in the deepest part of the Iberian Abyssal Plain, where we expect a minimal variability, as observed, and station 55 is located in the Iceland Basin (in the Maury Channel), where deep water properties vary much more.

Additionally, the theta-S diagrams were plotted for all the casts of 2023 in Figure 28.
<figure><img src="image_34.png" /><figcaption>Figure 27: Theta-S comparisons for deep waters of CTD stations made at (top) 40.333°N 12.223°W in Iberian Abyssal Plain, and (bottom) 54.762°N 26.125°W in Iceland Basin, since 2010. Numbers indicate pressure level every 1000dbar.</figcaption></figure>
<figure><img src="image_35.png" /><figcaption>Figure 28: All Theta-S for BOCATS 2023 cruise

The color of the profiles changes gradually from blue (profile 1 to red profile 126). Isopycnals of potential density referenced to the surface are plotted in black.</figcaption></figure>
### 6.3.4 Update of the chemical file

The chemical file created in the paragraph 6.3.1 will be updated by:

- correcting the conductivity data with the polynomial correction obtained

- preparing the file to the calculation of the better oxygen polynomial correction

Actually, the oxygen data in the file come from the bottle file of the station so taken during the upcast. These data are disturbed with turbulences during the closure of the bottles, and they are also more affected by the sensor hysteresis that is never completely corrected. The idea is to replace these data by the equivalent data at the same density level of closure from the downcast of the files `bo23st***corr_PTC.cnv` generated just above.

### 6.3.5 Calculation of the polynomial correction in oxygen

#### Operating mode

The method used to adjust the probe measurements to the chemistry measurements ($OXY_c$ in ml/l) involves the determination of the coefficients M and B of the equation below to minimize the differences between them.

$$ \frac{OXY_c}{\varphi} = OXY_s \times M + B $$

**Remark:** This equation is the developed equation indicated in the paragraph 4.4

where:

$$ \varphi = OX_{sol} \times (1 + A \times T + B \times T^2 + C \times T^3) \times e^{(E \times \frac{P}{K})} $$

$OXY_s$: data measurement of the probe in Volt

$$ M = Soc $$

$$ B = V_{offset} \times Soc $$

The $Soc$ and $V_{offset}$ coefficients (deduced from the values of M and B) of the Seabird sensor characteristics are determined for a set of samples, using successive iterations based on a principle similar to that for the conductivity.

Thus, and if necessary, a pressure polynomial correction can be calculated (from degree 0 to 5):

$$ OXY_{corr} = OXY + A_0 + A_1 \times P + A_2 \times P^2 + \dots + A_5 \times P^5 $$

#### Analysis of the initial results and choice of the polynomial correction

The oxygen differences between oxygen bottle and oxygen sensor with hysteresis correction is plotted in different plots in function of oxygen, time and pressure (Figure 29).
<figure><img src="image_36.png" /><figcaption>Figure 29: Oxygen raw differences</figcaption></figure>

a) as a function of the oxygen,

b) as a function of the time (as the casts progress),

c) as a function of the pressure of the sampling level

By analyzing these raw results and to improve the distribution of the differences, we:

- divided the casts in 2 groups (M and B calculated for each group): 1-19 ; 20-126

- applied a polynomial pressure correction of degree 2
<table><caption>Table 2: oxygen polynomial correction applied</caption><thead><tr><th rowspan="2"></th><th colspan="2">Oxy coeff</th><th colspan="3">Pressure coeff</th></tr><tr><th>M</th><th>B</th><th>A<sub>2</sub></th><th>A<sub>1</sub></th><th>A<sub>0</sub></th></tr></thead><tbody><tr><td>Station 1-19</td><td>0.516793</td><td>-0.422798</td><td>-1.83568e-09</td><td>1.16228e-05</td><td>-0.00860891</td></tr><tr><td>Station 20-126</td><td>0.521026</td><td>-0.420501</td><td>-3.113e-09</td><td>1.74695e-05</td><td>-0.0123489</td></tr></tbody></table>

Figure 30 shows the results of the adjustment of the oxygen sensor with the application of corrections. All the dots are plotted (green dots kept as validated samples, red dots rejected) and about 95% of the samples have been kept for the determination of the oxygen correction.

<figure><img src="image_37.png" /><figcaption>Figure 30: Final oxygen calibration</figcaption></figure>

a) as a function of the oxygen,

b) as a function of the time (as the casts progress),

c) as a function of the pressure of the sampling level
The differences between the oxygen of the validated samples and the CTD adjusted oxygen measurements at the sampling level are visualized with histograms below. They confirm that the distribution of the differences is satisfactory and confirm the quality of the adjustment.

In 70 % of cases, the differences in oxygen are lower than ± 0.03 ml/l, while in 100.0 %, they are less than ± 0.08 ml/l. The standard deviation in oxygen is around 0.030 ml/l.

<figure><img src="image_38.png" /><figcaption>Figure 31: histogram of oxygen differences
a) for all the validated samples
b) for the validated samples at a pressure greater than 980dbar</figcaption></figure>

### 6.3.6 Application of the correction

The polynomial corrections in oxygen calculated above are applied to all the casts of the cruise and new files are created: bo23st***corr_PTC_oxy.cnv.
To check the data, the theta-O₂ diagram is plotted for all the casts in Figure 32. Oxygen profiles are also plotted in function of pressure and a zoom of the deep waters in the Iberian Abyssal Plain (Figure 33) show a good consistency and are also in close vicinity with Saunders' (1986) value of 5.67 ml/l.

<figure><img src="image_39.png" /><figcaption>Figure 32: All Theta-O₂ for BOCATS 2023 cruise
The color of the profiles changes gradually from blue (profile 1 to red profile 126)</figcaption></figure>
<figure><img src="image_40.png" /></figure>

<figure><img src="image_41.png" /><figcaption>Figure 33: Dissolved oxygen measurements: profiles and bottle data for stations 1-52 with a zoom on the North-East Atlantic Deep Water (below 3300 dbar):</figcaption></figure>

a) continuous measurements on the probe downcast profiles,

b) chemical measurements obtained on the samples.

The red line represents the reference value proposed by Saunders (1986) in the Northeast Atlantic.

### 6.3.7 Final update of the chemical file

The chemical file updated in the paragraph 6.3.4 is updated again by correcting the oxygen data with the polynomial correction obtained.

This final chemical file contains:

* Number of the station

* Number of the bottle

* Pressure measurement adjusted

* Temperature measurement adjusted

* Salinity measurements adjusted

* Oxygen measurements in ml/l adjusted

* Oxygen measurements in µmol/kg adjusted

* Potential temperature calculated

* Potential density calculated

* Immersion

* Salinity of the samples

* Oxygen in ml/l of the samples

* Oxygen in µmol/kg of the samples

For each indication, a quality flag is indicated (refer Appendix H).
### 6.3.8 Reduction in O2 and netcdf files creation

All of the calibration part of the data processing is done based on the total probe measurements at 24 Hz. The data are then reduced to one measurement per decibar.

The elimination of non-validated cycles and the data reduction was carried out using the parameter gradients as elimination criteria:

$$ \frac{|\text{ParamCycle}_N - \text{ParamCycle}_{N-1}|}{\text{PressionCycle}_N - \text{PressionCycle}_{N-1}} $$

A cycle is validated if the values of the gradients are lower than the selected thresholds. Initially, a determination of the gradient histograms allows us to choose threshold values beyond which the parameters will be rejected. After removal of non-validated cycles, the decimation of the data is performed by calculating, for each integer pressure value, the mean of the parameters on a 1 dbar-layer centered on this value.

The set of criteria used to reduce the probe measurements is described in the document: "Validation et Réduction des données de la sonde SBE9+", C. Kermabon, M. Arhan, Nov 2008.

The options used for the cruise are shown below:

Threshold values for stations:

- Echant. 1

- Nb val min 6

- Threshold P 0.5

- Threshold T, C surface 0.6

- Threshold T, C bottom 0.2

- Threshold O₂ (Volt) surf 1.8

- Threshold O₂ (Volt) fond 2.0

The downcast and upcast files were generated in netcdf format.

bo23d***_cli.nc for the downcasts

bo23a***_cli.nc for the upcasts

Those files are used as inputs for the following final validation

## 6.4 Data final validation

Hydro_val software, part of the Cadhyac software suite, is used:

- to validate the oxygen data of the probe

- to analyze the density inversions in order to flag the corresponding T, S, O2 data as bad, if necessary, and replace them by interpolated value later on.

### 6.4.1 Validation of the Oxygen profiles

The software flags as 'bad' (QC = 4), the small number of oxygen peaks which were not eliminated during the data reduction by testing the difference with the median over a centered window of N points. This is only done in the deep part of the profile since the variability above is too high.

The data is invalidated if these 2 conditions are present:

- Data pressure > Minimal pressure (data above minimal pressure are not changed)

- $|\text{Median} - \text{oxygen data}| \ge \text{standard deviation number} \times \text{std}$
  With,
  $$ \text{Minimal difference} \le \text{standard deviation number} \times \text{std} \le \text{Maximal difference} $$

The number of iterations and the parameter values are indicated in Table 3.
<table><caption>Table 3: options for validation of the oxygen profiles</caption><thead><tr><th></th><th>Downcast</th><th>upcast</th></tr></thead><tbody><tr><td>Minimal pressure:</td><td>2800</td><td>2800</td></tr><tr><td>Size of the window N:</td><td>80</td><td>80</td></tr><tr><td>Minimal difference:</td><td>0.005</td><td>0.005</td></tr><tr><td>Maximal difference:</td><td>1</td><td>1</td></tr><tr><td>Standard deviation number:</td><td>2.7</td><td>3.4</td></tr><tr><td>Iteration:</td><td>3</td><td>3</td></tr></tbody></table>

### 6.4.2 Density inversions

By superposing the reduced file, the adjusted file at 24 Hz and the file before loopedit at 24 Hz on the same graph, we can detect density inversions related to the drag of the probe.

We can see on the graph below (figure 46) that the peak at 407 and 408 dbar in T and C corresponds to the measurements recorded by the probe 3 dbar previously. This crossed water (blue arrows) was drawn in by the frame and pollutes the sensors when the probe slows down. These inversions are not at all physical: they must be identified and the quality flag is set to 4 (QC = 4) for all the parameters. During the transfer to the.clc.nc files (intermediate format before the multi-cast format), a linear interpolation will be performed at these locations.

<figure><img src="image_42.png" /><figcaption>Figure 34: example of invalidation of density inversions

* The reduce profile is shown in red
* The adjusted data at 24 Hz in black
* The data at 24Hz before loopedit in grey.</figcaption></figure>

After all those corrections in the "cli" netcdf files, "clc" netcdf files are generated to fill the missing levels with interpolated points (flagged 8) if gaps are not bigger than 10 dbar. Derived parameters like potential temperature, density ... are then added in those "clc" files, which are finally concatenated in the multi-station netcdf file that we called bo23_PRES.nc.
### 6.4.3 Correction of the flags of oxygen bottle data

Using downcast CTD $O_2$ data at the same pressure or density than the bottle samples to compare with oxygen sample measurements have several advantages:

- we gain precision since the rosette has less influence on the data when it's moving downward.

- we reduce the impact of the hysteresis effect on the oxygen sensor that is never totally corrected (indeed, the influence of the pressure on $O_2$ measurements is weaker during the downcast than during the upcast).

However, the drawback is that we also don't consider the changes in the water column between the upcast and the downcast. In the upper water column, those changes are mainly due to internal waves that heave the water masses up and down by several tens of meters (Saout-Grit et al., 2015), particularly in the upper water column. Consequently, we used the new feature of CADHYAC consisting in selecting the downcast data at the same density than the upcast bottle level (what we call hereafter the "bottle density level").

For the OVIDE-BOCATS data, this is not really an issue for the calibration, since we have many samples, and the chemical data that don't match the CTD-$O_2$ data are simply discarded from the calibration. Among the 2198 samples, only 174 were moved out by the calibration because of a too large discrepancy with the probe data. However, the side effect is that these chemical data were flagged bad, although only 65 were actually further than 3 standard deviations from the profile if we consider either the upcast data or the downcast data at the same pressure.

Since chemical data are distributed and widely used (particular by biogeochemists), it is important to flag the chemical data the best we can. This is why CTD-$O_2$ data and flags of chemical oxygen data are corrected after calibration in the final chemical database by associating the sample measurement to its best match with CTD data between (i) the downcast point adjusted in pressure (ii) the downcast point adjusted in density and (iii) the upcast point at the effective level where the bottle was closed. This way, 109 chemical oxygen data were rehabilitated, leaving only 65 chemical data flagged bad.

This processing improved also greatly the histogram of the difference between CTD and chemical data (Figure 35), with a standard deviation down to 0.9 instead of 1.3 µmol.kg⁻¹, better than the 1 µmol.kg⁻¹ value found for replicates in section 5.3.2. Since we need to include the bias of 0.1 µmol.kg⁻¹ (mainly due to the hysteresis effect), an accuracy of 1 µmol.kg⁻¹ could then be claimed on oxygen CTD data.

Note finally that those correction don't affect the calibration results and that the CTD-$O_2$ oxygen profiles were not corrected. The above changes appear:

- in the csv and excel sheet of the chemical data.

- in the chemical data of the multi-station netcdf file: variables CHPOXYLP, CHOXYLB_QC, CHPOXYKP and CHOXYKB_QC were updated, with previous values saved in CHPOXYLPD, CHOXYLBD_QC, CHPOXYKPD, CHOXYKBD_QC respectively.

Chemical data in the individual "cli" and "clc" netcdf files were unchanged.
<figure><img src="image_43.png" /></figure>

<figure><img src="image_44.png" /></figure>

Figure 35: Histogram of the oxygen difference between the chemical measurements flagged good and the probe data, in µmol.kg⁻¹: [top] using only downcast data at the bottle density level (same than in Figure 31 (top) but in µol/kg), [bottom] using the best match between chemical and probe data by using either upcast data, downcast data at the bottle pressure level or downcast data at the bottle density level
# 7 Precision of the BOCATS 2023 measurements

The calibration of the CTD measurements ends with the determination of the quality of the different types of measurements (probe and chemistry) by giving in the table below the accuracies for the different measurements of the cruise coming from a statistical treatment or directly from the constructor.

As a reminder, the accuracy for the different CTD sensors are evaluated in section 4 and 6.4.3, and the accuracy of chemical parameters are evaluated with the replicates in section 5.

<table><caption>Table 4: quality data measurements obtained for BOCATS 2021 cruise</caption><thead><tr><th>Probe Param</th><th>Value</th><th>Unit</th><th>Chemical Param</th><th>Value</th><th>Unit</th></tr></thead><tbody><tr><td>PRES</td><td>1</td><td>dbar</td><td></td><td></td><td></td></tr><tr><td>TEMP</td><td>0.001</td><td>°C</td><td></td><td></td><td></td></tr><tr><td>COND</td><td>0.001</td><td>mS/cm</td><td></td><td></td><td></td></tr><tr><td>PSAL</td><td>0.001</td><td></td><td>CHPSALB</td><td>0.001</td><td></td></tr><tr><td>OXYL</td><td>0.021</td><td>ml/l</td><td>CHOXYLB</td><td>0.018</td><td>ml/l</td></tr><tr><td>OXYK</td><td>1</td><td>µmol/kg</td><td>CHOXYKB</td><td>0.8</td><td>µmol/kg</td></tr><tr><td></td><td></td><td></td><td>CHTMPOB</td><td>0.5</td><td>°C</td></tr></tbody></table>

PRES: accuracy of the sensor given by the manufacturer

TEMP: accuracy of the sensor given by the manufacturer

COND: standard deviation of the differences Conductivity probe / Conductivity from the sample

PSAL: standard deviation of the differences Salinity probe / Salinity from the sample

CHPSALB: standard deviation of the replicates validated in salinity

OXYL: standard deviation of the differences Oxygen probe / Oxygen from the sample in ml/l

CHOXYLB: standard deviation of the replicates validated in oxygen (ml/l)

OXYK: standard deviation of the differences Oxygen probe / Oxygen from the sample in µmol/kg

CHOXYKB: standard deviation of the replicates validated in oxygen (µmol/kg)

CHTMPOB: accuracy of the thermometer used for the oxygen sampling
## 8 Sections

Following figures present the A25 (BOCATS-OVIDE) section for the different parameters.

### BOCATS 2 - OVIDE 2023

Potential Temperature (degC)

<figure><img src="image_45.png" /></figure>

### BOCATS 2 - OVIDE 2023

Salinity

<figure><img src="image_46.png" /></figure>
## BOCATS 2 - OVIDE 2023

Oxygen (micromol/kg)

<figure><img src="image_47.png" /></figure>

## BOCATS 2 - OVIDE 2023

Potential density referenced to 1000m

<figure><img src="image_48.png" /></figure>
BOCATS 2 - OVIDE 2023

Potential Vorticity (10⁻⁹ s⁻¹)

<figure><img src="image_49.png" /></figure>

BOCATS 2 - OVIDE 2023

Brunt-Vaisala period (h)

<figure><img src="image_50.png" /></figure>

Figure 36: Section A25-OVIDE: potential temperature, practical salinity, dissolved oxygen, potential density referenced at 1000dbar, potential vorticity (here approximated at f/g*N²*, without the relative vorticity), Brünt-Vaisala frequency (N²) converted in period (= 2π/N).
<figure><img src="image_51.png" /></figure>

<figure><img src="image_52.png" /></figure>

<figure><img src="image_53.png" /><figcaption>Figure 37: Section AR24 (Irminger Sea, 64.5°N ↔ 61°N, see Figure 2); same parameters than Figure 36</figcaption></figure>
<figure><img src="image_54.png" /><figcaption>Figure 38: Section on the Greenland shelf at 61°N; same parameters than Figure 36</figcaption></figure>
## 9 Bibliography

Bacon, S., Snaith H., Yelland M., 1999. An evaluation of some recent batches of IAPSO standard seawater. Journal of Atmospheric and Oceanic Technology: Vol. 17, No. 6, pp. 854–861.

Benson, B.B. and D. Krause, Jr., 1984. The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnol. Oceanogr., 29 (3), 620-632.

Branellec, P., Lherminier P.: Campagne OVIDE 2006, rapport de données CTD-O2. Rapport interne DRO/DOPS/LPO 09-03. https://archimer.ifremer.fr/doc/00210/32103/

Branellec, P., Ferron B., Lherminier P.: Campagne OVIDE 2008, rapport de données CTD-O2. Rapport interne ODE/OPS/LPO 11-03. https://archimer.ifremer.fr/doc/00210/32124/

Branellec Pierre, Thierry Virginie, 2013: OVIDE 2010 CTD-O2 Cruise report. ODE/LPO/13/01. https://archimer.ifremer.fr/doc/00210/32134/

Branellec, P., P. Lherminier, F. Desprez de Gésincourt, 2013: CATARINA 2012-Leg 1: CTD-O₂ data report. Rapp. Interne ODE/LPO/13-32, http://archimer.ifremer.fr/doc/00353/46406/

Branellec, Pierre, Pascale Lherminier, 2017: BOCATS 2016: CTD-O2 data report. Rapp. Interne ODE/LOPS/17-06. https://doi.org/10.13155/59190.

Branellec Pierre, Lherminier Pascale, Reynaud Thierry, Le Bihan Caroline, 2019: OVIDE 2018 CTD-O2 Data report. Rapp. Interne ODE/LOPS/19-01. https://doi.org/10.13155/86588

Huck, T., A. Billant, P. Branellec. OVIDE 2004, rapport de données CTD-O2. Rapport interne DRO/DOPS/LPO 06-01. https://archimer.ifremer.fr/doc/00210/32100/

Le Bihan Caroline, Lherminier Pascale, Le Bot Philippe, Hamon Michel (2023). BOCATS 2021 CTD-O2 data report. Ifremer. https://doi.org/10.13155/98984

Mantyla, A. W., 1993. The treatment of inconsistencies in Atlantic deep water salinity data. Deep-Sea Res., 41, 1387–1405.

Mercier, H., Billant A., Branellec P., Morin P., Messias M.J., Memery L., Thomas C, Honnorez J. Campagne Romanche 1: Données CTD-O2, Chimie et Bathymétrie. Rapport InterneLPO 92-02.

Mercier, H., A. Billant, P. Branellec. OVIDE 2002, rapport de données CTD-O2. Rapport interne DRO/DOPS/LPO 04-01. https://archimer.ifremer.fr/doc/00210/32082/

Mercier, Herlé, Pascale Lherminier, Artem Sarafanov, Fabienne Gaillard, Nathalie Daniault, Damien Desbruyères, Anastasia Falina, Bruno Ferron, Claire Gourcuff, Thierry Huck, Virginie Thierry, 2015: Variability of the meridional overturning circulation at the Greenland-Portugal OVIDE section from 1993 to 2010. Progress in Oceanography, 132, 250–261, doi: 10.1016/j-pocean.2013.11.001

Millard, R.C., 1982. CTD calibration and data processing techniques at WHOI using the 1978 practical salinity scale. International STD Conference and Workshop, San Diego (8-11 February 1982).

Pérez, Fiz F. and the BOCATS team, 2017: BOCATS cruise report, 17 June - 31 July 2016.

Saout-Grit, C., A. Ganachaud, C. Maes, L. Finot, L. Jamet, F. Baurand and J. Grelet, 2015: Calibration of CTD oxygen data collected in the Coral Sea during 2012 Bifurcation cruise. Mercator Ocean–Coriolis Quartely Newsletter – Special Issue #52-May 2015, p. 34–38. Open Access version: https://archimer.ifremer.fr/doc/00272/38321/

Saunders, P.M., 1986. The accuracy of measurement of salinity, oxygen and temperature in the deep ocean. J. Phys. Oceanogr., 16, 189-195.

The GO-SHIP Repeat Hydrography Manual: A Collection of Expert Reports and Guidelines. IOCCP Report No. 14, ICPO Publication Series No. 134, Version 1, 2010.

UNESCO, 1981. Background papers and supporting data on the Practical Salinity Scale, 1978. UNESCO Technical Papers in Marine Science, n° 37, 144 p.

## 10 Acknowledgments

This work received funding from the European Union's programme EuroGO-SHIP under grant agreement No 101094690, and from Ifremer. The cruise was supported by the BOCATS2 (PID2019-104279GB-C21) project funded by MCIN/AEI/10.13039/501100011033. We are very grateful to the captain and crew of the Sarmiento de Gamboa for their hard work.
Figure table

<table>
  <tbody>
    <tr>
      <td>Figure 1: R/V Sarmiento de Gamboa</td>
      <td>7</td>
    </tr>
    <tr>
      <td>Figure 2: map of the working area, with zooms in the Iberian and Greenland areas. Blue lines delimit coasts and EEZ limits and green lines the 3 and 12 Nm national waters. Black and white dots are CTD stations (white when numbered and circled in green when the VMP was deployed), red triangles are positions of float deployments, and the stations with redpoints was sampled for genomics.</td>
      <td>7</td>
    </tr>
    <tr>
      <td>Figure 3: Scientific team and UTM crew members</td>
      <td>8</td>
    </tr>
    <tr>
      <td>Figure 4: stations in the Ria of Vigo</td>
      <td>9</td>
    </tr>
    <tr>
      <td>Figure 5: Synoptic chart indicating the sampling levels for CTD</td>
      <td>9</td>
    </tr>
    <tr>
      <td>Figure 6: chronogram of the operations</td>
      <td>15</td>
    </tr>
    <tr>
      <td>Figure 7: LOPS CTD rosette</td>
      <td>17</td>
    </tr>
    <tr>
      <td>Figure 8: Upper LADCP on CTD frame</td>
      <td>17</td>
    </tr>
    <tr>
      <td>Figure 9: Monitoring of the pressure sensor drift during the cruise</td>
      <td>20</td>
    </tr>
    <tr>
      <td>Figure 10: pre-cruise calibration of the primary Temperature sensor n°2911</td>
      <td>21</td>
    </tr>
    <tr>
      <td>Figure 11: pre-cruise calibration of the secondary temperature sensor n°4594</td>
      <td>21</td>
    </tr>
    <tr>
      <td>Figure 12: Monitoring of the temperature sensor drift during the cruise</td>
      <td>22</td>
    </tr>
    <tr>
      <td>Figure 13: samples boxes</td>
      <td>24</td>
    </tr>
    <tr>
      <td>Figure 14: salinity sample</td>
      <td>24</td>
    </tr>
    <tr>
      <td>Figure 15: oxygen sample</td>
      <td>24</td>
    </tr>
    <tr>
      <td>Figure 16: Metrohm Ti Touch 916 oxygen analyzer with a platinum titrode, a 20 ml burette to deliver the sodium thiosulfate and a 5ml burette to deliver the potassium iodate</td>
      <td>24</td>
    </tr>
    <tr>
      <td>Figure 17: Guildline portasal 8410A salinometer</td>
      <td>24</td>
    </tr>
    <tr>
      <td>Figure 18: validated salinity replicates</td>
      <td>25</td>
    </tr>
    <tr>
      <td>Figure 19: histogram of the validated salinity replicates</td>
      <td>25</td>
    </tr>
    <tr>
      <td>Figure 20: validated oxygen replicates</td>
      <td>26</td>
    </tr>
    <tr>
      <td>Figure 21: histogram of the validated oxygen replicates</td>
      <td>26</td>
    </tr>
    <tr>
      <td>Figure 22: Hydro nett options used for BOCATS23</td>
      <td>27</td>
    </tr>
    <tr>
      <td>Figure 23: Conductivity raw differences</td>
      <td>31</td>
    </tr>
    <tr>
      <td>Figure 24: Final conductivity calibration</td>
      <td>32</td>
    </tr>
    <tr>
      <td>Figure 25: histogram of conductivity differences</td>
      <td>33</td>
    </tr>
    <tr>
      <td>Figure 26: histogram of salinity differences</td>
      <td>33</td>
    </tr>
    <tr>
      <td>Figure 27: Theta-S comparisons for deep waters of CTD stations made at (top) 40.333°N 12.223°W in Iberian Abyssal Plain, and (bottom) 54.762°N 26.125°W in Iceland Basin, since 2010. Numbers indicate pressure level every 1000dbar.</td>
      <td>34</td>
    </tr>
    <tr>
      <td>Figure 28: All Theta-S for BOCATS 2023 cruise</td>
      <td>35</td>
    </tr>
    <tr>
      <td>Figure 29: Oxygen raw differences</td>
      <td>37</td>
    </tr>
    <tr>
      <td>Figure 30: Final oxygen calibration</td>
      <td>38</td>
    </tr>
    <tr>
      <td>Figure 31: histogram of oxygen differences</td>
      <td>39</td>
    </tr>
    <tr>
      <td>Figure 32: All Theta-O<sub>2</sub> for BOCATS 2023 cruise</td>
      <td>40</td>
    </tr>
    <tr>
      <td>Figure 33: Dissolved oxygen measurements: profiles and bottle data for stations 1-52 with a zoom on the North-East Atlantic Deep Water (below 3300 dbar):</td>
      <td>41</td>
    </tr>
    <tr>
      <td>Figure 34: example of invalidation of density inversions</td>
      <td>43</td>
    </tr>
    <tr>
      <td>Figure 35: Histogram of the oxygen difference between the chemical measurements flagged good and the probe data, in µmol.kg-1: [top] using only downcast data at the bottle density level (same than in Figure 31 (top) but in µol/kg), [bottom] using the best match between chemical and probe data by using either upcast data, downcast data at the bottle pressure level or downcast data at the bottle density level</td>
      <td>45</td>
    </tr>
    <tr>
      <td>Figure 36: Section A25-OVIDE: potential temperature, practical salinity, dissolved oxygen, potential density referenced at 1000dbar, potential vorticity (here approximated at f/g*N<sup>2</sup>, without the relative vorticity), Brünt-Vaïsala frequency (N<sup>2</sup>) converted in period (= 2π/N).</td>
      <td>49</td>
    </tr>
    <tr>
      <td>Figure 37: Section AR24 (Irminger Sea, 64.5°N &rarr; 61°N, see Figure 2); same parameters than Figure 36</td>
      <td>50</td>
    </tr>
    <tr>
      <td>Figure 38: Section on the Greenland shelf at 61°N; same parameters than Figure 36</td>
      <td>51</td>
    </tr>
  </tbody>
</table>
A. Seabird pressure sensor of the 813 probe calibration

Sea-Bird GmbH

<figure><img src="image_55.png" /></figure>

SEA-BIRD
SCIENTIFIC

Sea-Bird GmbH
Postfach 1167
87401 Kempten
Germany

+49 831 9 60994 701

seabird.eu@seabird.com

www.seabird.com

SENSOR SERIAL NUMBER: 0813

CALIBRATION DATE: 28-Nov-22

DIGIQUARTZ COEFFICIENTS:

C1 = -4.480765e+004

C2 = -5.250438e-001

C3 = 1.424300e-002

D1 = 3.732300e-002

D2 = 0.000000e+000

T1 = 3.039466e+001

T2 = -4.630908e-004

T3 = 4.384490e-006

T4 = 1.785720e-009

T5 = 0.000000e+000

SBE 9plus PRESSURE CALIBRATION DATA

10000 psia S/N 98623

AD590M, AD590B, SLOPE AND OFFSET:

AD590M = 1.28893e-002

AD590B = -8.41874e+000

Slope = 1.00006

Offset = -3.0175 (dbars)

<table><thead><tr><th>PRESSURE (PSIA)</th><th>INSTRUMENT OUTPUT (Hz)</th><th>INSTRUMENT TEMPERATURE (°C)</th><th>INSTRUMENT PRESSURE (PSIA)</th><th>CORRECTED PRESSURE (PSIA)</th><th>RESIDUAL (PSIA)</th></tr></thead><tbody><tr><td>13.540</td><td>32915.80</td><td>21.7</td><td>18.141</td><td>13.765</td><td>0.225</td></tr><tr><td>1999.546</td><td>33635.60</td><td>21.7</td><td>2003.570</td><td>1999.304</td><td>-0.242</td></tr><tr><td>3987.387</td><td>34338.80</td><td>21.8</td><td>3991.225</td><td>3987.067</td><td>-0.320</td></tr><tr><td>5974.498</td><td>35025.60</td><td>21.8</td><td>5978.697</td><td>5974.649</td><td>0.151</td></tr><tr><td>7961.737</td><td>35697.00</td><td>21.8</td><td>7966.100</td><td>7962.162</td><td>0.425</td></tr><tr><td>9950.279</td><td>36354.00</td><td>21.8</td><td>9953.808</td><td>9949.980</td><td>-0.299</td></tr><tr><td>7962.056</td><td>35697.10</td><td>21.8</td><td>7966.365</td><td>7962.427</td><td>0.371</td></tr><tr><td>5974.808</td><td>35025.70</td><td>21.8</td><td>5978.943</td><td>5974.895</td><td>0.087</td></tr><tr><td>3987.783</td><td>34338.90</td><td>21.9</td><td>3991.429</td><td>3987.272</td><td>-0.511</td></tr><tr><td>1999.964</td><td>33635.70</td><td>21.9</td><td>2003.738</td><td>1999.472</td><td>-0.492</td></tr><tr><td>13.540</td><td>32916.00</td><td>21.9</td><td>18.525</td><td>14.148</td><td>0.608</td></tr></tbody></table>

$$ \text{Residual (PSIA) = corrected instrument pressure - reference pressure} $$

<figure><img src="image_56.png" /></figure>
## B. Seabird temperature sensor of the 813 probe calibration

Sea-Bird GmbH

<figure><img src="image_57.png" /></figure>

SEA-BIRD
SCIENTIFIC

Sea-Bird GmbH
Postfach 1167
87401 Kempten
Germany

+49 831 9 60994 701
seabird.eu@seabird.com
www.seabird.com

SENSOR SERIAL NUMBER: 2911
CALIBRATION DATE: 04-Nov-22

SBE 3 TEMPERATURE CALIBRATION DATA
ITS-90 TEMPERATURE SCALE

COEFFICIENTS:

g = 4.36422727e-003

h = 6.58390511e-004

i = 2.44014993e-005

j = 2.18374573e-006

f0 = 1000.0

<table><thead><tr><th>BATH TEMP<br>(°C)</th><th>INSTRUMENT<br>OUTPUT (Hz)</th><th>INST TEMP<br>(°C)</th><th>RESIDUAL<br>(°C)</th></tr></thead><tbody><tr><td>-1.5000</td><td>2933.514</td><td>-1.5000</td><td>0.00005</td></tr><tr><td>1.0000</td><td>3098.769</td><td>1.0000</td><td>-0.00004</td></tr><tr><td>4.5000</td><td>3341.254</td><td>4.4999</td><td>-0.00006</td></tr><tr><td>8.0000</td><td>3597.038</td><td>8.0000</td><td>0.00002</td></tr><tr><td>11.5000</td><td>3866.452</td><td>11.5000</td><td>-0.00000</td></tr><tr><td>15.0000</td><td>4149.846</td><td>15.0001</td><td>0.00009</td></tr><tr><td>18.5000</td><td>4447.519</td><td>18.5000</td><td>0.00002</td></tr><tr><td>22.0000</td><td>4759.798</td><td>21.9999</td><td>-0.00006</td></tr><tr><td>25.5000</td><td>5086.993</td><td>25.5000</td><td>-0.00002</td></tr><tr><td>29.0000</td><td>5429.380</td><td>29.0000</td><td>-0.00003</td></tr><tr><td>32.5000</td><td>5787.248</td><td>32.5000</td><td>0.00004</td></tr></tbody></table>

f = Instrument Output (Hz)

Temperature ITS-90 (°C) = 1/{g + h[ln(f0 / f)] + i[ln²(f0 / f)] + j[ln³(f0 / f)]} - 273.15

Residual (°C) = instrument temperature - bath temperature

<figure><img src="image_58.png" /></figure>
C. Seabird Conductivity sensor of the 813 probe calibration

Sea-Bird GmbH

<figure><img src="image_59.png" /></figure>

SEA-BIRD
SCIENTIFIC

Sea-Bird GmbH
Postfach 1167
87401 Kempten
Germany

+49 831 9 60994 701
seabird.eu@seabird.com
www.seabird.com

SENSOR SERIAL NUMBER: 3194
CALIBRATION DATE: 27-Oct-22

SBE 4 CONDUCTIVITY CALIBRATION DATA
PSS 1978: C(35,15,0) = 4.2914 Siemens/meter

COEFFICIENTS:

g = -1.01556512e+001
h = 1.40617900e+000
i = -9.15978403e-005
j = 7.92315570e-005

CPcor = -9.5700e-008 (nominal)
CTcor = 3.2500e-006 (nominal)

<table><thead><tr><th>BATH TEMP<br>(°C)</th><th>BATH SAL<br>(PSU)</th><th>BATH COND<br>(S/m)</th><th>INSTRUMENT<br>OUTPUT (kHz)</th><th>INSTRUMENT<br>COND (S/m)</th><th>RESIDUAL<br>(S/m)</th></tr></thead><tbody><tr><td>0.0000</td><td>0.0000</td><td>0.0000</td><td>2.68710</td><td>0.0000</td><td>0.0000</td></tr><tr><td>-1.0000</td><td>34.8074</td><td>2.80393</td><td>5.20862</td><td>2.80391</td><td>-0.00002</td></tr><tr><td>1.0000</td><td>34.8077</td><td>2.97530</td><td>5.32407</td><td>2.97533</td><td>0.00003</td></tr><tr><td>15.0000</td><td>34.8091</td><td>4.27082</td><td>6.12627</td><td>4.27084</td><td>0.00001</td></tr><tr><td>18.5000</td><td>34.8096</td><td>4.61758</td><td>6.32360</td><td>4.61752</td><td>-0.00005</td></tr><tr><td>29.0000</td><td>34.8066</td><td>5.70091</td><td>6.90375</td><td>5.70098</td><td>0.00008</td></tr><tr><td>32.5001</td><td>34.7998</td><td>6.07345</td><td>7.09213</td><td>6.07340</td><td>-0.00005</td></tr></tbody></table>

f = Instrument Output (kHz)

t = temperature (°C); p = pressure (decibars); δ = CTcor; ε = CPcor;

Conductivity (S/m) = (g + h * f² + i * f³ + j * f⁴) / 10 (1 + δ * t + ε * p)

Residual (Siemens/meter) = instrument conductivity - bath conductivity

<figure><img src="image_60.png" /></figure>

POST CRUISE
CALIBRATION
D. Seabird oxygen sensor of the 813 probe calibration

<figure><img src="image_61.png" /></figure>

SEA-BIRD
SCIENTIFIC

Sea-Bird Scientific
13431 NE 20th Street
Bellevue, WA 98005
USA

+1 425-643-9866

seabird@seabird.com
www.seabird.com

SENSOR SERIAL NUMBER: 1402
CALIBRATION DATE: 23-Feb-23

COEFFICIENTS:

Soc = 0.5119

Voffset = -0.4761

Tau20 = 1.03

A = -4.8098e-003

B = 2.0704e-004

C = -3.1285e-006

E nominal = 0.036

SBE 43 OXYGEN CALIBRATION DATA

NOMINAL DYNAMIC COEFFICIENTS

D1 = 1.92634e-4

D2 = -4.64803e-2

H1 = -3.300000e-2

H2 = 5.00000e+3

H3 = 1.45000e+3

<table><thead><tr><th>BATH<br>OXYGEN (ml/l)</th><th>BATH<br>TEMPERATURE (°C)</th><th>BATH<br>SALINITY (PSU)</th><th>INSTRUMENT<br>OUTPUT (volts)</th><th>INSTRUMENT<br>OXYGEN (ml/l)</th><th>RESIDUAL<br>(ml/l)</th></tr></thead><tbody><tr><td>1.17</td><td>2.00</td><td>0.00</td><td>0.715</td><td>1.17</td><td>0.00</td></tr><tr><td>1.18</td><td>6.00</td><td>0.00</td><td>0.746</td><td>1.18</td><td>-0.00</td></tr><tr><td>1.18</td><td>12.00</td><td>0.00</td><td>0.792</td><td>1.18</td><td>-0.00</td></tr><tr><td>1.20</td><td>20.00</td><td>0.00</td><td>0.859</td><td>1.20</td><td>-0.00</td></tr><tr><td>1.21</td><td>26.00</td><td>0.00</td><td>0.908</td><td>1.21</td><td>0.00</td></tr><tr><td>1.21</td><td>30.00</td><td>0.00</td><td>0.942</td><td>1.21</td><td>0.00</td></tr><tr><td>3.97</td><td>2.00</td><td>0.00</td><td>1.286</td><td>3.97</td><td>0.00</td></tr><tr><td>3.98</td><td>6.00</td><td>0.00</td><td>1.390</td><td>3.99</td><td>0.00</td></tr><tr><td>4.01</td><td>12.00</td><td>0.00</td><td>1.550</td><td>4.01</td><td>-0.00</td></tr><tr><td>4.04</td><td>20.00</td><td>0.00</td><td>1.768</td><td>4.04</td><td>0.00</td></tr><tr><td>4.06</td><td>26.00</td><td>0.00</td><td>1.932</td><td>4.06</td><td>0.00</td></tr><tr><td>4.07</td><td>30.00</td><td>0.00</td><td>2.044</td><td>4.06</td><td>-0.00</td></tr><tr><td>6.81</td><td>2.00</td><td>0.00</td><td>1.862</td><td>6.80</td><td>-0.00</td></tr><tr><td>6.85</td><td>6.00</td><td>0.00</td><td>2.047</td><td>6.85</td><td>0.00</td></tr><tr><td>6.94</td><td>12.00</td><td>0.00</td><td>2.335</td><td>6.94</td><td>0.00</td></tr><tr><td>7.00</td><td>30.00</td><td>0.00</td><td>3.178</td><td>7.01</td><td>0.00</td></tr><tr><td>7.02</td><td>20.00</td><td>0.00</td><td>2.718</td><td>7.02</td><td>-0.00</td></tr><tr><td>7.07</td><td>26.00</td><td>0.00</td><td>3.010</td><td>7.07</td><td>-0.00</td></tr></tbody></table>

V = instrument output (volts); T = temperature (°C); S = salinity (PSU); K = temperature (°K)

Oxsol(T,S) = oxygen saturation (ml/l); P = pressure (dbar)

Oxygen (ml/l) = Soc * (V + Voffset) * (1.0 + A * T + B * T² + C * T³) * Oxsol(T,S) * exp(E * P / K)

Residual (ml/l) = instrument oxygen - bath oxygen

<figure><img src="image_62.png" /></figure>

CALIBRATION
AFTER
MODIFICATIONS
E. Salinity sampling protocol

Salinity sampling protocol

<figure><img src="image_63.png" /></figure>

<figure><img src="image_64.png" /></figure>

➤ Take a flask in the box (check the presence of the seal).

➤ Rinse the flask and the seal 3 times with the water to sample

> Fill the flask entirely then just remove a little of water (until the point indicated)

<figure><img src="image_65.png" /></figure>

➤ Close the flask and rinse it with fresh water

<figure><img src="image_66.png" /></figure>

➤ Continue until the last sample then bring the box in the chemical analysis container
## F. Oxygen sampling protocol

<figure><img src="image_67.png" /></figure>

# User's guide for dissolved oxygen sampling

1. Put the gloves.

2. Purge the reagent distributors of R1 and R2 to be sure that there is no bubbles in the tubes.

3. Take :

✓ A flask in the box and check that the number on the flask and on the cap are in agreement.

✓ The sampling tube.

✓ The thermometer.

4. Give the number information to the secretary.

5. Start the sampling :

✓ Install the sampling tube on the tap.

✓ Drain the tube and be sure that no bubbles are present.

✓ Pinch the tube and inside it to the bottom of the flask a little inclined.

✓ Release the tube carefully to not create a vortex or bubbles.

✓ Let overflow the water (3 times the volume of the flask) and take the temperature.

✓ Pinch again the tube to reduce the flow (don't stop the flow) and get out the tube.

✓ Stop the flow of the niskin bottle.

6. Inject the reagents R1 (pink) then R2.

7. Close the flask and start the agitation during 30 seconds minimum.

8. Apply the same protocol for the others samples of the station.

<figure><img src="image_68.png" /></figure>

<figure><img src="image_69.png" /></figure>

The order of the reagents
is important!!!!

<figure><img src="image_70.png" /></figure>

**At the end of the station** : shake again very softly all the samples of the station and add distilled water in the top of the flasks.

Créé par CLB le 09/01/2020
G. Oxygen sampling analysis

User's guide for dissolved oxygen analysis

<figure><img src="image_71.png" /></figure>

1. Put the gloves and check that the method on the titrator is « oxy3 ».

2. Check on the container's PC that the software esaytitrino has been launched.

3. Put out the excess of water.

<figure><img src="image_72.png" /></figure>

4. Open the flask and rinse the bottom of the cap with distilled water.
(to be sure to have all the precipitate for the analysis)

<figure><img src="image_73.png" /></figure>

5. Add the acid (R3) then the bar magnet.

<figure><img src="image_74.png" /></figure>

+ 1ml of acid

+

<figure><img src="image_75.png" /></figure>

The order acid then stirrer is really
important.

6. Put in the titrod and the anti diffusion tube in the flask on the magnetic stirrer.

7. Push on « START » then write

➤ the station number,

➤ The flask number,

➤ The flask volume. (confirm by « Entrée » each time)

<figure><img src="image_76.png" /></figure>

The anti diffusion tube must always be behind the
titrode and never be glue on it.
## H. Quality Flag

During Cadhyac treatment, each data will be marked with a quality flag:

1 good

4 bad

9 no data

During the generation of the clc file, some flags can appear:

2 probably good

8 interpolated
Figures of the CTD and associated bottle data

The following pages present plots showing (top-left) θ-S diagram, (top-right) θ-Ox diagram and (bottom) profiles of CTD temperature, salinity and dissolved oxygen as a function of pressure, along with bottle data (points). On top figures, all stations are plotted in grey while the specified station appears in red.
STATION 1

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STATION 2

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STATION 10

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STATION 10 CAST 2

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STATION 29

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STATION 30

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STATION 30 CAST 2

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STATION 37

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STATION 39

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STATION 40

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STATION 41

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STATION 42

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STATION 43

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STATION 44

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STATION 45

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STATION 45 CAST 2

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STATION 46

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STATION 47

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STATION 48

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STATION 49

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STATION 51

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STATION 53

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STATION 55

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STATION 58

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STATION 59

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STATION 60

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STATION 61

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STATION 62

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STATION 62 CAST 2

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STATION 63

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STATION 64

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STATION 65

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STATION 67

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STATION 69

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STATION 70

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STATION 71

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STATION 72

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STATION 83

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STATION 83 CAST 2

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STATION 86

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STATION 90

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STATION 110

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STATION 111

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STATION 112

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STATION 116

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STATION 117

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STATION 120

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STATION 121

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STATION 122

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STATION 123

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STATION 124

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STATION 125

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STATION 126

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