Central Irminger Sea (CIS) station

Location of  Central Irminger Sea (CIS) station
Location of Central Irminger Sea (CIS) station

Why observing here?

The Irminger Sea a very cold and rough region in the North Atlantic. Strong winds blow cold air from the massive ice-shield of Greenland right over the Irminger Sea.

A tanker ploughing through the rough weather in the Central Irminger Sea.

The cold winds , cool down the surface waters which then become colder and denser. Water masses below the surface, which are not subjected to the wind, are not cooled as much, and are therefore less dense and more buoyant than the water above. This results in an overturn which brings the cooled heavy surface water to depth, and the more buoyant waters at depth up to the surface. If the cold wind persists, this “new” surface water is also cooled and sinks, and so on.

THE OCEAN CONVEYOR — A global system of currents, often called the "ocean conveyor" carries warm surface waters from the tropics northward. At high latitudes, the waters cool, releasing heat to the atmosphere and moderating wintertime climate in the North Atlantic region. The colder (and denser) waters sink and flow southward in the deep ocean to keep the conveyor moving. (Illustration by Jack Cook, WHOI)

With time, this surface overturning generates a deep layer of cold water. There are only a few regions in the global ocean where the atmospheric and oceanic conditions are such that these very deep layers of cold water are generated. The deep layers can be viewed as “exchange windows” between the deep sea and the atmosphere and as such they are particularly important to bring “information” (e.g. gases as oxygen and carbon dioxide) from the surface to the deep sea.

SENSITIVE SEAS — Cold, dense waters that propel the ocean conveyor form and accumulate primarily in certain locations in the North Atlantic—in the Greenland, Iceland, and Norwegian Seas and in the Labrador, Irminger, and Iceland Basins. (Illustration by Jack Cook, WHOI)

For more than a century the Irminger Sea has been suspected to be one of these regions but in recent years at least, the deep cold water formation was not very effective and reached maybe only 500 m depth.

The decrease of deep water formation could be due to a number of reasons, for example the winds were not cold (and long lasting) enough to cool the surface water, or the surface water was too warm. The complex interplay between atmospheric forcing and the oceans response motivates the installation of the CIS deep sea observatory in the Central Irminger Sea.

Scientists or technicians in charge of the observatory

Andreas Pinck
Johannes Karstensen
Gerd Niehus

Name of their institution

Leibniz-Institute for Marine Sciences IFM-GEOMAR, Kiel, Germany

Distance from shore

About 80 nautical miles from the rural Greenland coast (2 days sailing from Reykjavik (Island) or St. John's (Canada))

Max depth

2800 m