Performance of theRIN KO FT opticaldissolved oxygen sensors
attached to Argo floats
Herminio Foloni-Neto
Oceanographic Research Lab.
JFE Advantech Co., Ltd.

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February 2020

2

JFE Advantech Co., Ltd.
Parameters

Current meters Conductivity
 Temperature
 Pressure Dissolved oxygen Currents
 Fluorescence Turbidity
 PAR
 pH, ORP

Compact loggers

Moored loggers
with wiper

Dissolved oxygen: RIN KO®

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

Profilers

OEM sensors
for integration

Loggers fordeep sea

February 2020

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Measurement principle
 RIN KO ® is an optical dissolved oxygen sensor

water
O2LED (blue)

O2O2Sensing foil
Phosphorescence (Red)

Receiver

RINKO ® means phosphorescence in Japanese
Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

Measurement principle
PhosphorescencequenchingO2 Permeation

Porphyrin (excited)

O2 Sensing Foil

Excitation Light (LED)

Phosphorescence

Phosphorescence intensity is not stable
Phosphorescence life time(is what the sensor measures)

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Porphyrin (ground)February 2020

5

Development
As result, we can provide various types of sensing foil
We are one of the few
manufacturers in theworld that provide bothsensing foils and opticalsystem technologies.
No. 165 for Argo floats

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

RINKO® for Argo floats(Development challenges)

 Maintain fast-response Long-term stability (small drift over time) High accuracy Small size, low power consumption

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

February 2020

RINKO FT

7(RINKO® for Argo floats) Fast-response•

Robust sensing foil with increased gaspermeability

 Long-term stability (small drift overtime)•

Controlled excitation light emission inorder to avoid deterioration of theoxygen sensing foilCopyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

February 2020

8RINKO FT(RINKO® for Argo floats) High accuracy•

Modified Stern-Volmer equation isapplied (Uchida et al., 2010).

•Multipoint direct calibration

 Small size, low power consumption•ϕ30 x 146 mm,•

162g in water•

Operation mode: less than 30 mA
Sleep mode: less than 0.1 mA

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

RINKO FT - Fast response
Fast response is essential to understand fine-scale DO variability.
A slow O2 time response reduces fine-scale resolution and causes alag between in situ and observed O2 profiles (Bittig & Körtzinger, 2017).

RINKO FT response time(63%): less than 1s in water(63% response time)

Time series of DO in water at
25 °C measured by RINKO FT.

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

RINKO FT – High accuracy
RINKO FT accuracy: ± 2 % of measured value or ± 2.0 μmol L-1• 16-point calibration• 4-point verification.

• DO reference standard from National Metrology Institute of Japan NMIJ certified traceable gases with air saturation values of approx.
20%, 50%, 80% and 120%.
Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

RINKO FT – High accuracy
RINKO FT accuracy: ± 2 % of measured value or ± 2.0 μmol L-1

120%100%80%
50%20%• More accurate• It does not require a reference to be compared with, such as
Winkler titration – minimizing systematic and experimental error).

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

RINKO FT – High accuracy
 “Aging process” applied at factory to newly
made DO sensing foil in order to overcome
the initial drift.
 RINKO FT can be easily detached from thefloat for calibration just before deployment

User 2-point calibration
RINKO FT is designed to satisfy therequired accuracy for a number of years
without the need for recalibration.

In case of long-term storage: user calibration kit is available as an option,
including a cable and a GUI software.

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

February 2020

RINKO FT – Performance13

We have integrated RINKO-FT on different platforms(floats and gliders).

APEX float from
Teledyne Marine

S3A
MRV floats

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SEAEXPLORER Glider fromAlseamar
Deep APEX float from
Teledyne MarineFebruary 2020

RINKO FT – Performance We analyzed data from BGC Argo floats equippedwith RINKO FTRussia

 Floats deployedby JAMSTEC
Japan

PacificOcean

 This is a work in collaboration with JAMSTEC(Japan Agency for Marine-Earth Science and Technology)
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February 2020

RINKO FT – Performance NO adjustment applied to data labeled as “realtime

QC mode data” made available by Argo’s website.

 We analyzed DO profiles down to 2000 m depth.
• 07/2014 to 01/2016 - MRV S3A(WMO ID2902530)• 07/2018 to 07/2019 - APEX (WMO ID2903354)(still operational as July 2019)

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February 2020

RINKO FT – Performance

 DO

minimum or maximum thin layers, as well as sharp
gradients can be identified by the RINKO FT

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February 2020

RINKO FT – Performance RINKO FT reveals fine scale DO distribution that cannot be

obtained by slow response sensors or water sampling RINKO FT DO concentrationagreed well with Winkler (bluecircles)
ΔDO < 2 μmol kg-1

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17February 2020

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RINKO FT – Long-term stability
No remarkable drift

Sal.

µmol kg-1σθ = 27.60σθ = 27.60

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

• 2014: less than 1 μmol kg-1
• 2018: less than 2 μmol kg-1℃dbar

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RINKO FT – Conclusions and next steps
 High accuracy: RINKO FT agrees well with values obtained from Winkler(difference is below 2 μmol kg-1)
 Fast response: allowed for fine scale DO gradient observations
 Small drift: DO varied within 1 μmol kg-1 after several pressure cycles.

Pressure-induced effect:RINKO® sensing foils did
not present noticeable
time-dependent pressureinduced effect at 1000 m(parking depth).
(Uchida, H. et al. 2018 – poster pres. at
6th Argo Science Workshop, Tokyo,Japan)ーarticle under preparation

Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

Next steps:
RINKO-FT performance in the deep

ocean (using Deep Argo floats andlaboratory experiments).
- analyzing pressure-induced effects
and its correction.

Thank you
Copyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.

February 2020

21RINKO FTA

SResponse time
(63%)

<1s

<8s

<6s

Initial accuracy±2 μmol L-1
or ±2 %

±2.5 μmol L-1
or ± 1.5 %±3 μmol kg-1
or ±2 %

Resolution< 0.1 μmol L-1< 1 μmol L-1

0.2 μmol kg-1

Sampling speed

1 Hz1 Hz

1 Hz

Depth rating

2000 m/6700 m

6000 m7000 mCopyright © 2020 [JFE Advantech Co. Ltd.]. All Rights Reserved.