Changes in anthropogenic carbon storage in the Northeast Pacific in the last decade

[Journal of Geophysical Research: Oceans]Supporting Information for Changes in anthropogenic carbon storage in the Northeast Pacific in the last decade Program in Oceanography/Applied Oc

[Journal of Geophysical Research: Oceans]

Supporting Information for

Changes in anthropogenic carbon storage in the Northeast Pacific in the last decade

Program in Oceanography/Applied Ocean Science and Engineering, 77 Massachusetts Avenue, Cambridge, MA 02139, USA

Institution, 266 Woods Hole Road, Woods Hole, MA 02543, USA

Woods Hole, MA 02543, USA

*Corresponding author: Zhaohui Aleck Wang, zawang@whoi.edu

Contents of this file

Text S1

Figures S1 to S2

Introduction

The supporting information provides 1 Text and 2 Figures Text S1 presents the

the deep crossover analyses used to correct the offsets of various parameters between

2001 and 2012 P17N cruises Figure S2 presents the multiple linear regression residuals for the 2012 P17N cruise

Text S1 Sample analysis procedures for dissolved oxygen and salinity

Dissolved oxygen (DO) samples were collected from CTD Niskin bottles into 150

mL brown glass tincture bottles Sodium iodide-sodium hydroxide mixture and manganese chloride were added sequentially to the sample immediately after collection and mixed thoroughly One mL of sulfuric acid was added and mixed into the sample prior to measurement DO samples were measured after temperature equilibration, within

3 days, on an automated dissolved oxygen titrator developed at Woods Hole

Oceanographic Institution [Knapp et al 1990] The system is based on the Winkler

concentrations of dissolved oxygen < 90 μmol kgmol kg-1 In situ temperature was used to

samples Ideally, the conversion temperature should be the temperature measured at the time of sample drawing, but those were not measured Bottle values were used to calibrate CTD values

Salinity samples were collected into 250 mL square cross-sectioned, borosilicate glass bottles and measured on an Autosal Salinometer (Guildline 8400B) PSS-78 salinity was calculated from measured conductivity ratios Measurements were performed after samples had equilibrated to laboratory temperature, within 3 days after collection The machine was standardized for each group of analyses, approximately 50 samples International Association for the Physical Sciences of the Oceans (IAPSO) Standard Seawater Batch P-152 was used for standardization This method has an accuracy of

±0.003 and precision of ± 0.0002 Bottle analyses were used to calibrate CTD salinity values

Figure S1 Deep isopycnal crossover analyses were used to correct systematic offsets

between different cruise occupations of similar locations Results from the analysis are shown in Table 1 in the main paper Data from >2000 m for CLIVAR 2001 (red) and NH1208 2012 (blue) was plotted against potential density referenced to 3000 dbar (σ3) and fit by a second-order polynomial If an offset was found, NH1208 2012 cruise data was corrected to the CLIVAR 2001 data The corrected data is plotted in green a)

salinity vs σ3 b) phosphate vs σ3 c) nitrate vs σ3 d) silicate vs σ3 e) dissolved oxygen

vs σ3 f) dissolved inorganic carbon vs σ3 g) total alkalinity vs σ3

a

34.57

34.59

34.61

34.63

34.65

34.67

σ 3 [kgm -3 ]

CLIVAR 2001 NH1208 2012

2.5

2.6

2.7

2.8

2.9

3

3.1

3.2

-1 ]

σ 3 [kgm -3 ]

CLIVAR 2001 NH1208 2012 NH1208 2012 corrected

c

36

37

38

39

40

41

42

43

44

45

-1 ]

σ 3 [kgm -3 ]

CLIVAR 2001 NH1208 2012

140

145

150

155

160

165

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185

190

-1 ]

σ 3 [kgm -3 ]

CLIVAR 2001 NH1208 2012 NH1208 2012 corrected

e

40

50

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120

-1 ]

σ 3 [kgm -3 ]

CLIVAR 2001 NH1208 2012 NH1208 2012 corrected

2320

2330

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2350

2360

2370

2380

2390

2400

-1 ]

σ 3 [kgm -3 ]

CLIVAR 2001 NH1208 2012 NH1208 2012 corrected

g

2390

2400

2410

2420

2430

2440

2450

2460

-1 ]

σ 3 [kgm -3 ]

CLIVAR 2001 NH1208 2012 NH1208 2012 corrected

Figure S 2 Residuals between the DIC MLR model and measured values from the 2012 NH1208 cruise plotted against potential density, latitude, and depth show no significant trends, confirming that binning the dataset by potential density or latitude would not