Week 5
31 July 2006

More Underway Than Meets the Eye

The Science in the Spotlight articles feature the different research projects that are taking place here on board. However, many people are not aware that data are being collected constantly and made available to scientists all over the world. These data are collected through the Underway System.

Jeff Morin, Marine Science Technician at Moon Pool (water intake for Underway System)

I. The Underway System consists of instruments that collect ocean data from the time the ship leaves the dock until the time that the ship returns. The ship’s route may cover ocean waters around Chile, Antarctica, New Zealand, South Africa and waters in between. Having this system of instruments continually on board eliminates the necessity of shipping and then setting up these instruments for each particular cruise. Data collection can begin as soon as the cruise is underway.

Data is collected every second during the cruise. At the end of the cruise, each principal investigator is given a CD/DVD that contains the information recorded. The scientists are then able to study other variables which they had no time to consider while collecting their own information. An example would be data on temperature and salinity collected while on the cruise track. In addition, this data can be sent to other scientists who are not participating on the cruise but use this information in their research.

Another very important measurement taken by the Underway System is the level of CO2 in the water. In a stable environment, one that has not been altered by people, the ocean keeps the amount of CO2 in the atmosphere at a constant level.  The ocean absorbs excess CO2 from the atmosphere and in addition, plants remove CO2 from the atmosphere to use in the process of photosynthesis. This balance has been disrupted because of the increasing amounts of fossils fuels used by people.
The burning of fossil fuels adds large quantities of CO2 to the atmosphere, more than the ocean can absorb. Increased levels of CO2 play a role in the warming of the planet. If the ice caps melt due to this warming, the natural flow of the ocean currents could be disrupted resulting in catastrophic weather changes.

Instruments in the Underway System:

These instruments are part of a continuous flow system that samples water while the ship is in transit.

1. Fluorometer – The fluorometer is used to measure the amount of chlorophyll in the water.  The fluorometer sends a beam of light through the water. The algae in the water fluoresce, and the scientists measure the fluorescence to determine the amount of algae present.

Fluorometer

2. Transmissometer – The transmissometer is used to measure the amount of particles in the water. A beam of light shines on the water. Scientists then measure the amount of light that is able to pass through to the other side. The more particles there are in the water, the less light will be able to pass to the other side.

3. Thermosalinograph – The thermosalinograph measures temperature and salinity up to a depth of 6 meters.

The Southern Ocean has many different water masses and currents. These areas possess differing densities due to their temperatures and salt content. These areas are usually quite distinct, despite some mixing. The measurements from the thermosalinograph can help determine where the boundaries of the water masses are.

II. Meteorological System – This system measures wind speed, temperature, the dew point and humidity. It also uses photoactive radiation (PAR) to determine the amount of light available to plants for photosynthesis.

III. Multi-Beam

The multi-beam has 100 sensors that scan across the bottom of the ocean floor. It uses a sound pulse to create a picture of the topography of the ocean floor. In contrast, the other instrument used to measure depth, the Knudsen, sends out a sound pulse that indicates the depth of one particular location.

Undersea mapping from multi-beam	Example imagery from various multibeam survey projects Link

All these instruments provide the scientists on board, and other interested scientists as well, with data that help them find out more about the processes that are taking place in the ocean.

Question: What natural processes are taking place in the environment in which you live? For example, if you live on the coast, you are aware that there is a high and a low tide. How much do you know about the causes of these cycles? What instruments would help you to find out more information about these cycles?