南极海冰和极涡指数的时空特征及相互关系

本文采用聚类分析方法将南极海冰距平划分成５个变化相似的区域。并计算了对应各区的南半球５００ｈＰａ极涡面积和强度指数。分析了海冰与极涡指数的时空特征及相互关系。结果表明，不同区域的海冰和极涡的气候特征和年际变化的差异十分显著。１区和４区的海冰变化最大。海冰范围和极涡指数在多数区都在２－２．５ａ和５－７ａ的振荡周期。仅发现１区海冰范围是扩张趋势，其他４个区都呈收缩趋势。南极平均海冰范围以１．６个纬度／

VARIATIONS OF THE ANTARCTIC SEA ICE AND POLAR VORTEX INDEX IN SOUTHERN HEMISPHERE AND THEIR RELATIONSHIPS

In this paper Cluster Analysis was used for grouping the similar regions of the variability of the Antarctic sea ice, and five regions were obtained based on the Antarctic sea ice extent data of 17 year period (1973--1989). The indices of the polar vortex area and the intensity in southern hemisphere were calculated using of 500hPa monthly mean data in the same period.The analysis of the features of temporal and spatial variations of the Antarctic sea ice and polar vortex as well as their relationships is presented by using statistic analysis. The results show that the discrepancy of climatic characteristics and interannual variability of the sea ice and polar vortex are obvious. They oscillate with cycles of 2 2. 5 years and 5 7 years over most of the regions. The linear trend of the sea ice anomaly reveals that 4 of the 5 regions exhibit a trend of reducing sea ice.The trends of the polar vortex coverage anomaly for all regions are negative similar to that of sea ice, while the corresponding trends of polar vortex intensity are predominantly positive over 3 regions. The above statistical facts is consistent with the effect of global warming.Cross-correlations among concurrent anomalies of the variables are most signifcant from the Southeast Pacific area (e. g., Antarctic Peninsula, region 5) to the South Atlantic area (region 1 ). Lag correlations between them are also closer to the sea ice leading the polar vortex cover and lagging the polar vortex intensity in region 1. The correlations are larger with the sea ice lagging both of the cover and intensity of the polar vortexm in region 5.