Porcupine Abyssal Plain station

Location of Porcupine Abyssal Plain station
Location of Porcupine Abyssal Plain station

PAP News

Shot and short time-series (30/5/2010 – 4/6/2010) of the deep seafloor (4800m) in May 2010 at the PAP site (49N, 16.5 W). Time-lapse of one shot every 8 hours :

You can also watch a 1 minute film.

Why observing here?

Characteristics of the oceanic region

The PAP site lies in the Northeast Atlantic Ocean in the middle of a region called the "North Atlantic Drift Province". Here, a warm ocean current, the North Atlantic Drift, crosses the region from east to west. This is an extension of the Gulf Stream and transports warmer waters from south-eastern USA(Florida area) across to Europe. The North Atlantic region is made up of a complicated layering of currents going in many different directions:

© Rapid Climate Change, Circulation of warm (red) and cold (blue) currents in the North Atlantic

A stream of clockwise and anticlockwise swirls and eddies, from 5 to hundreds of kilometers wide, cross the site at irregular intervals going down as deep as several thousand meters into the ocean.

In winter, the water column is mixed down to 800 m depth by strong convection currents. In Summer, the mixing reduces and the ocean becomes more layered, or stratified, reducing the mixed layer to only a few tens of meters thick.

Ocean stratification : The oceanic water column is stratified with warmer water on the surface. In warm, calm conditions this stratification is intensified and becomes more resistant to mixing by surface winds. This mixing is actually critical for bringing more nutrients from deeper water to replenish those being used in the upper layers. In more temperate areas stratification of the water column occurs during the warmer summer months. When winter comes the water cools, and together with the action of winter winds, stratification is broken down. This seasonal cycle is important as winter mixing brings nutrients from deeper waters to the surface. Phytoplankton can then utilise the nutrients in spring and summer, once stratification forms to trap them in the warm waters near the surface. Abnormally elevated summer temperatures will create greater stratification and winter winds will be less able to mix these two layers.

Particular characteristics of the site

The PAP site is a remote location in the open ocean characterised by rough seas and intense mixing of different water layers, especially during the winter when storms are common. This makes it difficult to access and scientists leave equipment out at sea to monitor the ocean year-round without the need to travel there.

When the intense mixing occurs, many nutrients needed by marine organisms for growth, are recycled to the surface from the deep nutrient-rich layers and become available for microscopic plants, phytoplankton. This results in intense blooms of phytoplankton each spring, which fall out through the water to the seafloor once they die. This provides seasonal pulses of food to deep-sea animals e.g. sea cucumbers living in the water and on the seabed below.

© _ SeaWiFS Proj_ NASA, Coccolithophores bloom visible from satellite.

The North Atlantic is also an area of the ocean where carbon dioxide is absorbed from the atmosphere to the oceans at a very high rate. This makes the North Atlantic Ocean a 'CO2 sink' trapping atmospheric CO2, good news for climate change. But the oceans can only absorb so much carbon dioxide and there are signs the rate of absorption is declining.

Scientists or technicians in charge of the observatory

10
Dr. Richard Lampitt
11
Dr. David Billett

Name of their institution

National Oceanographic Centre, Southampton, England

Distance from shore

300 nautical miles (~1.5 days steaming at 8-9 knots)

Max depth

4800 m