The Arctic Ocean in the global climate system (review)
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概要
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The oceanic portion of the Arctic climate system has a strong influence on global climate change. This is because, first, the Arctic Ocean can change its capacity for redistribution of solar heat in consequence of the changes of thermohaline structure of the upper layer and the sea ice area on its surface, second; the vertical oceanic circulation in high latitudes is very sensitive to changes of the fresh water balance on the ocean surface that can cause a profound effect on the production of the new deep water and on the global vertical ocean circulation. The increase of fresh water discharge into the Arctic Ocean can be one manifestation of global warming. An estimation for 1938-93 showed increase of discharge of main arctic rivers, rise of precipitation on the arctic river basins and decrease of snow depth on the Arctic Ocean sea ice. Data of regular oceanographic observations indicate decrease of upper layer salinity in the Siberian Arctic seas during 1950-1990. These climatic signals correlate with data on interannual variations of the arctic sea ice area. The strongest variations of the sea ice area occurred in the Atlantic Arctic. Freshening of the Arctic Ocean upper layer appears also in the Greenland Sea, where decrease of salinity and reduction of the frequency of deep winter convection events was found. Oceanographic data for 1950-1990s show that the salinity of the upper layer required for deep convection is attained due to permanent inflow of transformed Atlantic water into the Greenland Sea Gyre. This water arrives to the Arctic Ocean, where it constitutes the main salt source. The Atlantic water inflow in the North European Basin and the Arctic Ocean is prone to appreciable interannual variations that are assessed from oceanographic observations in the Faeroe-Shetland Channel for 1902-1990. Distribution and characteristics of the transformed Atlantic water in the Arctic Ocean vary from year to year. According to Russian oceanographic data there was water temperature and salinity reduction from 1950s to 1970s in the Arctic Ocean that was more detectable in the Eurasian Subbasin. These data make it possible to trace the intrusion of the transformed Atlantic water and to detect traces of cold intermediate and deep water formation in the St. Anna trough, near eastern Severnaya Zemla shelf and in the eastern part of the Barents Sea.
- 国立極地研究所の論文
著者
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Alekseev G.
Arctic And Antarctic Research Institute
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Zakharov V.
Arctic And Antarctic Research Institute
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Ivanov V.
Arctic and Antarctic Research Institute
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Yanes A.
Arctic and Antarctic Research Institute