Abstract:

Sea ice is an important component of the ocean–atmosphere system, and forms part of the sensitive response and feedback mechanisms in the global climate system. In this paper, spatio-temporal variations and trends of Antarctic and Arctic sea ice were analyzed using sea ice concentration data from 1992 to 2008 obtained from European Space Agency. Combining these data with NCEP (National Centers for Environmental Prediction)/NCAR(National Center for Atmospheric Research) air temperatures and ENSO indices, impact factors of sea ice variation were calculated. Results indicate that Arctic sea ice exhibits a statistically significant trend of −6.88×104 km²·a⁻¹; sea ice concentration during the month of minimum sea ice cover in summer has been changing at an even higher rate of −10.18×104 km²·a^–1. The highest and most statistically significant trends are found in the Arctic Ocean, Barents Sea, Kara Sea, Baffin Bay and Labrador Sea (generally exceeding −1.2%·a⁻¹). Antarctic sea ice exhibits a small trend (below +0.5%·a⁻¹) that is not statistically significant. Sea ice concentration has increased in the Ross Sea and the South Pacific and South Atlantic sectors of the Southern Ocean. Correlations between air temperature and sea ice cover with a lag of 1 month are negative and statistically significant. Trends in air temperature increase are statistically significant in the Arctic; the largest magnitudes are found in the Arctic Ocean, Hudson Bay, Baffin Bay, Kara Sea, Barents Sea, and the Chukchi Sea where sea ice has decreased considerably. However, in the Antarctic, air temperature decreased in the South Pacific and South Atlantic sectors where sea ice has increased slightly. Arctic sea ice decrease is highly correlated with decreasing ONI with a lag of 39 months and increasing SOI with a lag of 40 months. Antarctic sea ice increase is highly correlated with decreasing ONI with a lag of 7 months and increasing SOI with a lag of 6 months. There is a strong correspondence between polar sea ice variations and three strong warm and cold ENSO events.

Key words: sea ice, concentration, area, air temperature, ENSO, Antarctica/Arctic