ICOS Science Conference: Day 1, Session 6

1. E. Hammermeister*1,2
, M. Arundell1
, E. Papadimitriou1
, A. Schaap1
, M. Mowlem1,2
, S. Loucaides1
1
Na onal Oceanography Centre Southampton 2
University of Southampton
State of the Art Autonomous CO2 System Measurements On-board Boaty
McBoa ace: Results from an 8-day Mission in the Cel c Sea

2. Objec ve:
NERC OCEANIDS Programme DY149 Research Cruise March 2022
TA pH
DIC
New genera on of
autonomous Lab-On-Chip
(LOC) sensors measuring pH,
Dissolved Inorganic Carbon
(DIC), and Total Alkalinity (TA)
developed and integrated onto
the Autosub Long Range (ALR)
Autonomous Underwater
Vehicle
• Address ocean carbonate chemistry observa on capability gaps.
• Demonstrate the Carbonate Chemistry Autonomous Sensor
System (CarCASS) project on a marine autonomous
pla orm in an opera onal se ng at sea.
• Validate sensor longevity, opera on, and analy cal
performance.

3. • ALR Integra on / Deployment
- pH, TA, DIC sensors on-board
• CTD Sampling / Valida on
- Discrete water samples
- Co-sampling at ALR depths
• Underway Sampling / Valida on
-Discrete water samples
(0600,1200,1800)
-pH, TA, DIC sampling ~ hourly
20 ALR Missions
1-12hr dura on
14 Days
44 Loca ons
18 CTD Casts
16 Sta ons
159 water samples
Methods:
Sampling Plan & Structure
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4. Methods:
Sampling Map

5. Preliminary Results:
Underway System pH Valida on
Underway pH measurements over me from
the LOC sensor and discrete water "valida on"
samples.
Underway pH sensor data show very close
agreement with valida on samples.
Bo om plot shows the variability between the
two measurements with an
average difference of 0.0024 pH.

6. Preliminary Results:
ALR Missions
Figure. ALR Mission days 1-3 comple ng deep dives with pH and temperature values collected from the
ALR. CTD casts 9-13 correspond to CTD Sta ons OS-A through OS-B.

7. Preliminary Results:
ALR Missions
Figure. ALR Mission days 5-8 comple ng staircase dives. pH and DIC values collected from the autosub. CTD casts
17-28 correspond to CTD Sta ons T1-T10.

8. • Sensors show good performance producing data in all ALR missions and on ship's
underway system.
• Preliminary data show good agreement between ALR sensor measurements and
valida on water samples.
• Preliminary data show reasonable and expected trends between pH,
temperature, depth, and DIC throughout the water column during ALR missions
and CTD casts.
Next Steps
• Sensor data currently undergoing QA/QC.
• TA/ DIC sensor signal processing is s ll performed manually.
• Plan to use carbonate parameters to characterise the carbonate
system and create model of the region.

9. Acknowledgements: This technology is being developed by the Ocean Technology and Engineering Group at NOC and
funded through NERC’s Marine Sensor Capital fund. Project: Carbonate Chemistry Autonomous Sensor System (CarCASS)
NE/PO2081X/1. Apprecia on to the captain and crew of the RRS Discovery as well as the Marine Autonomous Systems
(MARS) group and ALR team at NOC.
e.m.hamermeister@soton.ac.uk