Seasonal polar vortex centric intensity is very persistent.
季节的极涡中心强度是持续的。
It is evident positive relative between the Arctic sea ice and the polar vortex area, yet the relation between the polar vortex area and intensity is so complex.
北极海冰面积和北半球极涡面积为明显的正相关，而北半球极涡面积和极涡强度之间的关系就较为复杂。
The main results show as following: (1) There is obvious inter-annual and inter-decadal variation for polar vortex, including the variation of area, intensity and location.
主要结论如下：(1)北半球及各分区极涡的面积、强度及位置有着很明显的年际及年代际变化。
Before middle age of 1970s, area and intensity index of northern polar vortex trend to rise, with small fluctuating, and after that, with clear undulating, it trend to minish.
上世纪70年代中期之前极涡面积、强度基本为上升阶段，之后为下降阶段。
Before middle age of 1970s, area and intensity index of northern polar vortex trend to rise, with small fluctuating, and after that, with clear undulating, it trend to minish.
上世纪70年代中期之前极涡面积、强度基本为上升阶段，之后为下降阶段。
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