In the depths of the ocean reduces the amount of cold dense water

March 22. A significant decrease in the number of cold deep waters — the so-called Antarctic Bottom Water — In the Southern Ocean in 1980 2011.

Sarah Perks from the University of Washington and Gregory Johnson of the National Oceanic and Atmospheric Administration (USA) found that Antarctic Bottom Water mass decreases at an average rate of about 8 million tons / s, which is about 50 times greater than the average volume flow of the Mississippi and one-quarter the Gulf Stream in the Florida Straits.

A layer of Antarctic bottom water temperatures are below zero (dark blue areas indicate the thickest layer, white — the absence of such water), covers the bottom of the ocean around Antarctica (center, highlighted in gray). Shows the rate at which this layer subsided during the study (meters per decade). Deep-water pools are separated from each other by thin gray lines. Note: sea water remains liquid even at temperatures close to £ 2? C, because of the high salt content.

The Antarctic Bottom Water mass is formed in a few places around Antarctica where the sea water is air-cooled and becomes more saline as a result of the formation of ice. Condense water then sinks to the bottom and flows north, filling part of the ocean's depths greater rigor around the world and slowly mixed with warm overlying layers.

These deeper currents play an important role in the transport of heat and carbon, thereby regulating the climate. Changes in temperature, salinity, the amount of dissolved oxygen and carbon dioxide has important consequences: for example, they affect sea level rise and the rate of absorption of heat from the Earth.

Previous studies have already shown that in the last decade, bottom waters are warmed and desalinate. At this time also found that such water is formed downward. "We are not sure if this is part of the long-term trend or cycle," — said Mr. Johnson.

The expert also emphasizes that recent studies often focused on the currents of the North Atlantic Ocean, which is the main indicator of climate change. But the Southern Ocean has undergone significant changes, which also play an important role in the climate cycle.

The analysis used high-precision temperature measurements made by An international program of oceanographic research ship.

The results of the study are published in the Journal of Climate.

Based on: National Oceanic and Atmospheric Administration of the United States
Source: Kompyulenta

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