Peppering the Arctic with measuring instruments
In DAMOCLES, one of the largest EU research project to date, the Arctic is peppered with state of the art measuring instruments worth millions of euros to better predict climate change and generate more accurate weather and ocean forecasts.
Edmond Hansen of the Norwegian Polar Institute holding a CTD. Photo: Laura de Steur
In response to the rapid decline in sea ice the EU has contributed €17.1 million to the research project spanning four years from 2005 to 2009. The total funding of DAMOCLES activity is close to €30 million as each participating country must match the EUs contribution.
The project aims to better understand and predict how climate change will affect the Arctic. One key concern has been that while the rest of the world is monitored by meteorological and oceanic instruments, the Arctic has never been subject to a comparable level of monitoring.
This autumn and next spring will see the deployment of several different instruments designed to measure ocean temperature, salinity, ice extent, ice thickness, ocean currents and air temperature, just to mention a few. The very first instruments were deployed in 2006.
Some of the new instruments:
Ice tethered profilers (ITP) – Ocean measuring
Unmanned buoys attached to drifting sea ice measure the heat and salinity of the ocean below are dispatched all over the ice-covered Arctic. They lower in instrument called CTD (conductivity temperature density) to collect data on heat and salinity. Some times an ADCP (Acoustic Doppler Current Profiler) is also fixed to the ice to measure the strength of the current.
The buoys communicate with satellites and send data in real time to scientists in Europe.
Ice tethered sondes (ITS) – Atmosphere measuring
A device used to observe the upper atmosphere is secured to the ice by a wire and lifted by balloons. The sonde can travel up to 2,000 metres into atmosphere before it is pulled back down. These devices are man operated and used by expeditions such as Tara and the NP-35.
Sound waves are used to ocean measure temperature in the Fram strait. The device consists of a sound source (an under water loud speaker) and a receiver. The source is anchored to the sea bed about 1,500 metres below the surface, not too far from the shelf break, where it floats at 300 metres depth. The receiver floats in the midst of the Fram strait where it picks up the signals. Because sound travels quicker in warm water than in cold water, scientists can monitor the water temperature in the Fram strait. The frequency of the sound emitted is carefully selected not to disturb the ocean wild life.
This is a floating device with an upward-looking sonar attached to it. It stays at a constant depth in the ocean under the ice. By sending sound signals towards the ice and measuring the time it takes for the sound to return, it is possible to measure the ice thickness. If you know the device floats 50 metres below the surface and then measure the distance to the ice to be 48 metres, you can quite accurately calculate the ice thickness. In this case it would be around 2.2 metres because 90 percent of the ice floats under water.
These buoys are placed on the ice in great numbers and measure air pressure, air temperature and its own position. Data is transmitted world wide in real time through the global transmission system (GTS).
Ice mass balance (IMB)
One part of the instrument is placed on top of the ice while the other is secured beneath the ice. They are both acoustic projectors and use sound to measure the thickness of the ice. Simultaneously they measure the ice temperature using a chain of sensors placed in a shaft drilled through the ice.
These are torpedo shaped robots that measure temperature, salinity, pressure and speed as they travel through the ocean at different depths. As opposed to the ITPs, which drift wherever the sea ice takes them, the gliders are remotely navigated by pilots on land. Thus the glider can monitor an entire system of ocean currents. Because the glider sends data to satellites, scientist can monitor the water masses in real time.
Bottom Anchored profiling current meters
Sometimes we need to monitor the ocean state in a specific place over a long time. In that case we anchor the instruments to the sea bottom. Such bottom-anchored instruments have been deployed along the edge of the Arctic Ocean, where strong currents carry the warm Atlantic waters from the North Atlantic into the central Arctic.
Drifting station Tara
Ice drift through the Arctic Ocean from the Siberian side towards Greenland. When Nansen made his famous drifting voyage with Fram in the 1890s, it took him three years. Because the ice moves faster today, the polar schooner Tara will emerge from the ice after a little over a year.
On board, scientists take turns to study the effects of climate change. Observations are simultaneously carried out in the atmosphere up to 1,500 metres altitude, in the ocean down to 4.000 metres depth and through the few meters of ice that separate them. They are measuring water temperatures and salinity, atmospheric temperature and pressure along with the intensity and direction of winds and currents. An array of 16 weather beacons has been set up with Tara in the centre. Another array of 20 oceanographic beacons has been deployed in the heart of the Arctic Ocean.
Drifting station NP-35
The Russian drifting station consists of 30 container-like cabins, 22 scientists and weighs 300 tonnes.
It was meant to be placed on an ice floe in the core of the transpolar drift. But due to the this year’s record low sea ice minimum, no perennial ice was found while exploring the Arctic Ocean between Siberia to Canada and the station had to be placed at the periphery near Cap Artichevsky, off the shore of Severnaya Zemlya.
The Russian scientists will be investigating the upper ocean layer and sea ice, as well as snow cover. Atmospheric measurements of meteorological parameters such as temperature, wind, humidity and air pressure, will be added through recordings of trace gases such as carbon dioxide and ozone.
Several ice breakers such as the German vessel Polarstern, Akademik Fedorov of Russia and the Swedish ship Oden have all been on research cruises in the Arctic Ocean this autumn deploying instruments and taking measurements.
Satellites have been used to monitor the Arctic for 30 years. There is a number of meteorological and oceanographical satellites that fly in so called polar orbits, which give very good observation coverage at high latitudes.
In connection with The International Polar Year (IPY) and projects like Damocles there is an emphasis on using these data, especially those concerning the sea ice. The satellite measurements over sea ice are dependent on the sea ice surface such as ice age and snow cover, as well as on the atmosphere above the ice surface namely water vapour and clouds.
Projects like Damocles give a unique opportunity to study this and by that make ground for improved understanding of the related physics as well as improved use of satellite data.
Satellites from the American space organisation NASA and its European counterpart ESA together with the meteorological satellites from National Oceanic and Atmospheric Administration NOAA form the back bone of the satellite surveillance system.