The Instrumentation System
The system measures concentrations of CO2 dissolved in seawater and in the atmosphere. To interpret this data additional measurements are made of the ships position, seawater - salinity, temperature and dissolved oxygen concentrations and the total pressure of gasses dissolved in the seawater in addition air - temperature, pressure and humidity are measured. All the measurements are logged on a computer in the engine room. The full data set is sub-sampled at 5 minute intervals and this data is transmitted to NOC Southampton every 6 hours via a satellite link. At NOC data is then passed to this public access web page.
Designing system to work on the global route of the MV Pacific Celebes presented a major challenge. It needed a robust system capable of collecting high quality scientific data for four to five months. During this time the ship’s crew would be able to carryout simple servicing tasks but visits from NOC staff would not be possible. This need was met by being able to new instrumentation designed for long-term deployment on ocean moorings.
The 4 main scientific instrument packages and control units aboard the MV Pacific Celebes are:-
In the engine room a stainless steel tank connected to ships pumped seawater supply containing measuring devices for dissolved carbon dioxide and oxygen, total dissolved gas pressure, temperature and conductivity.-
In the engine room an electronics cabinet containing the main data logging, control computer and DC power supplies.
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On the Monkey Island a Stevenson Screen box containing sensors measuring humidity, air temperature and atmospheric carbon dioxide content.
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On the Monkey Island an electronics cabinet containing an Iridium satellite modem, GPS receiver and data logger.
The layout is shown schematically on the right.
All the instruments measuring seawater components are housed in a single flow through tank in the engine room. (For a detailed drawing of the tank click here). This is fed by water from supply set up in parallel to that being pumped to the ship’s desalination plant. It contains instruments measuring:-
• Temperature (Aanderaa 4050)
• Conductivity (Aanderaa 3919)
• Dissolved Oxygen (Aanderaa Optode)
• Total dissolved gas pressure (ProOceanus GTD)
• Partial pressure of dissolved Carbon Dioxide (ProOceanus CO2-Pro)
Additionally sea surface temperature is measured using a hull mounted Seabird SBE48 temperature sensor. In the Stevenson Screen on the Monkey Island the concentration of carbon dioxide gas in the atmosphere is measured using a Vaisala GMP343 CO2 probe and atmospheric pressure, temperature and humidity are measured using a Vaisala PTU200.
Pictures of the SNOMS equipment in the engine room of the MV Pacific Celebes are shown below:
SNOMS equipment in the engine room of the MV Pacific Celebes. On the left is the electronics box and display screen. On the right is the SNOMS tank containing the in water sensors. The hull mounted temperature sensor can be seen between the two white struts attached to the tank.
View into the SNOMS tank. The ProOceanus CO2Pro is at the bottom of the picture with the GTD at the top. The SBE 48 tank temperature sensor is to the left of the tank with its insulation removed.
View into the lid of the tank while the Aanderaa “Smart Sensors” are being cleaned.
Pictures of the SNOMS equipment on the Monkey Island of the MV Pacific Celebes are shown below:
 Picture of the Stevenson Screen containing the atmospheric sensors with the GPS receiving system and Iridium transmission and receiving systems mounted in the yellow case above it. |
 View of the Vaisala GMP343 CO2 sensor in the Stevenson Screen. |