The mystery of Antarctic interglacial Lake
4hw.com.cn: June 15 (Xinhua) according to a news release recently released by the University of Washington, researchers of the University and their peers found the reasons for the emergence of huge interglacial lakes in Antarctic sea ice in 2016 and 2017 by using the data collected by satellites, ocean buoys and seals.
In polar winter, ice free areas sometimes appear in the frozen ocean, called inter ice lakes, which are 'oases' for marine animals to breathe and forage. Coastal interglacial lakes are mainly caused by floating ice blown off the coast by strong winds, but the formation mechanism of giant pelagic interglacial lakes has always been a mystery.
In the 1970s, a giant interglacial Lake appeared in the Weddell Sea of Antarctica for several consecutive years, and disappeared in the following decades. People once thought it was a rare accidental phenomenon and would not reappear. However, in 2016 and 2017, a giant ice lake with an area of 33000 square kilometers and 50000 square kilometers appeared again in the sea area.
Researchers from the University of Washington and other institutions reported in the British journal Nature that they used various data to analyze the causes of the Weddell Sea ice lake in 2016 and 2017. Some of these data come from satellite observations, some from ocean buoys in the Weddell Sea, and some from a project using marine animals for observation, collected by seals equipped with sensors.
The analysis shows that the winter storm in the sea area has been particularly strong in the past two years, breaking the stable stratification of sea water and generating convection different from that in normal years. The upwelling trend of warmer seawater in the lower layer is enhanced. After reaching the surface, the density becomes larger and sinks again. This cycle process will inhibit the freezing of the surface. In addition, there are strong winds to promote the dispersion of floating ice and other reasons, which also led to the emergence of inter ice lake.
The researchers say that the ice lake in the 1970s may have been spawned by a similar mechanism. Giant interglacial lakes have an impact on ocean currents, the atmosphere and the carbon cycle. The seabed stores a large amount of organic carbon from biological remains, and seawater upwelling will bring the carbon to the surface. If giant interglacial lakes appear for several consecutive years, it may lead to a large amount of carbon entering the atmosphere and exacerbate climate change. On the other hand, with global warming, ice lakes may appear more and more frequently.