The Research On Antarctic Sea Ice Variation, Sea-level Change And Their Relationship

The Antarctic ice and snow area is the biggest cold source and one of the main freezing region of the heat engine of global hydrosphere circulation. It is the key and sensitive area to climate change. Antarctic sea ice is the border area between the Antarctic continent and the sub-Antarctica and the interface between upper of the ocean and lower of the atmosphere. Moreover, it is an important region for physical biogeochemical interaction, and has an important effect on ocean, atmosphere and climatic environment. This paper uses the sea ice concentration data (from January 1, 1979 to December 31, 2007) and sea level anomaly data(from December, 1992 to December, 2008) which provided separate by NSIDC and AVISO. After data preprocessing, it applies the methods, such as curve fitting, EOF analysis, to systematic study of the variations in Antarctic sea ice and global sea-level and the discussion of the relationship between Antarctic sea ice variation and sea-level changes. Conclusions are as follows:Firstly, Antarctic sea ice area has a very significant change in the annual cycle, and has regional differences during the period 1979-2007. It comes to minimum in February and maximum in September each year and increases with the speed of 1.3×104km2/yr. Details specific to five seas of Antarctica: only the sea ice area of Bellingshausen Amundsen Sea decreases (-1.0×104 km2/yr); sea ice area of Ross Sea grows fastest(1.4×104 km2/y), followed by Weddell Sea (0.51×104 km2/y); sea ice area of Indian Oceanic and the Pacific Oceanic Sea changes slowly by 0.31×104 km2/y and 0.12×104 km2/y. And then sea ice area cycle of Antarctica is closely to ENSO's. In Antarctic Peninsula around Weddell Sea the sea ice covers more in West than East, but opposite to Ross Sea; each year during the ice melting from September to the following year in February, the ice concentration in the east of Weddell Sea nearby 60°S, the Ross Ice Shelf of Ross Sea and the Antarctic continental margin start reduction first.Secondly, global sea-level has significant seasonal change, and its change is different in different regions in 1993-2008. The sea-level trends of global, Southern and Northern Hemisphere rise respectively with the rate of 2.921mm/y, 3.347mm/y, 2.33mm/y, but not straight. Distribution of sea-level in Pacific Ocean is remarkable. Its annual averaged sea-level height shows higher in North-east and lower in South-west. Furthermore, the 10°N is an important boundary to sea-level of the equatorial Pacific. Sea-level height in two sides of this boundary shows higher in North and lower in South in March-May contrary to the phenomenon in September-November, which also can be confirmed in the map of period-latitude diagram of averaged sea-level height over all longitudes. Sea-level change has teleconnection in the region between 5°S and 10°N and North hemisphere, the same to the region between 10°N and 15°N and Southern hemisphere, for their synchronous change. EOF analysis shows that signal displays remarkable in EI-Nino region in global sea-level change on seasonal-annual scale.Thirdly, the response of sea level to seasonal variation of sea ice is remarkable. The cycle of mean sea level changes in northern and southern hemispheres, region ranged from 20°S to 50°S and five seas of Antarctica is closely to the variation of Antarctic sea ice's. sea level has teleconnection with sea ice in the mid-latitudes of Southern Hemisphere. Due to the effect of ocean current etc, sea level of the sea around Antarctica could not response to the variation of sea ice timely in short time, but quickly in long period.