Variation Of Antarctic Sea Ice And Its Relationship With The Summer Weather And Climate

Sea ice is a very important part of climate system .And its change has important effect on Global Climate Change .The sea ice spatio-temporal variation in Antarctica is larger than that in Arctic ,so its effect on climate is in turn more important .Using sea ice concentration dataset covering the period 1968-2002 obtained from the Hadley Center of UK ,the temporal series of representative characteristic regions concerning sea ice variation in Antarctica are found and the characters of Antarctic sea ice variations are presented .Combining with global atmospheric circulation indices ,totally 74,the 500hPa and 100hPa atmospheric circulation in Northern Hemisphere and rainfall and temperature data about 160 stations of China ,the relationship between Antarctic sea ice and the circulation system and climate in Summer of China are revealed .The research demonstrated that the mean sea-ice extent is consistent with sea ice area by and large ,to choose the sea-ice extent as an index of researching the Antarctic sea ice spatio-temporal variation is reasonable .The maximum and the minimum of Antarctic sea ice appear in September and February respectively . The maximum and the maximal variation of sea ice appear in Weddell sea and Ross sea .While the minimum and the minimal variation of sea-ice appear in Antarctic Peninsula .In recent 35 years ,as a whole ,the sea ice in Antarctica decrease distinctly .There are 5 subdivision regions in total considering their different variation .Thereinto , the sea-ice extent of Weddell sea and Ross sea regions extend and area increases ,while sea-ice extent the other three regions shrinks and area decreases .They are all of obvious 2~3 years and 5~7 years significant oscillation periods .The change of Antarctic sea ice and global atmospheric circulation are related closely .The different change in each region has different influence on circulation of both Northern and Southern Hemisphere .The results show that both Ross Sea and Weddell Sea are the key regions for the summer synoptic climate of China and the variation of their sea ice is of indication for the subsequent rainfall and temperature forecast of our country .For the Ross Sea ,if its antecedent sea ice is below normal ,the West Pacific Subtropical High will stronger than its normal considering ahead of 6-9 months' situation .Besides ,it will affect the climate in North-East ,Northern China and small parts of Sinkiang with precipitation increasing and temperature decreasing .It ismore complex correspondingly in South China .On the one hand ,they are affected by the decreasing of the sea ice in Ross Sea directly .On the other hand ,the North-West Pacific Subtropical High and South Asia High which vary with the sea ice variation will impose secondary force on climate in China .The widely increased temperature and rainfall distribution behaving either increased or decreased along North-West to South-East are represented .What's more ,the influence of antecedent sea ice of Weddell Sea on eastern hemisphere is later than that on western hemisphere .The anticorrelation is dominant in western hemisphere ,while for eastern hemisphere the positive correlation is dominant .Considering ahead of 7~10 months' situation ,if the sea ice of this region is below normal , the position of West Pacific Subtropical High will more western and the Northeast Low will weaker .And the higher temperature and less precipitation will occur in the east region of North-East .While lower temperature and more precipitation will occur in the south of the middle reaches of Yellow River and the north of Sinkiang .Moreover ,the Antarctic Sea-ice Extent Oscillation Index (ASEOI ) according to the mean sea ice extent in Ross Sea and Antarctic Peninsula is defined .This index is of good correlation(r=0.77) with Antarctic Sea-ice Oscillation Index (ASOI ) defined by sea ice concentration .But it is much more convenient when calculating .In term of the relationship between ASEOI and circulation in Northern Hemisphere ,both South Asia High and Indian Low weaken when...