| Based on the NCEP/NCAR 2.5°x2.5° monthly reanalysis and the Arctic l°xl°sea ice intensity data calculated the index of the polar vortex area and the intensity and the Arctic sea ice, the research of spatial and temporal change characteristic of the Arctic sea ice area and the polar vortex on the Northern Hemisphere and their relationship each other shows:1) The Arctic sea ice area and the polar vortex on the Northern Hemisphere have the evident seasonal change, the time of appearance of the sea ice max(min) index lags that of the polar vortex area and intensity max(min) index 1-2 months, this indicates, in short time, the sea ice climatic characteristics are strongly effected by the air seasonal change .2) The maritime space of the Arctic center is covered by sea ice all the time, while there are some seasonal sea ice in the other sea region, such as Barling sea on the Northern Pacific Ocean, the Okhotsk sea and some inner sea in Eurasia (for instance the Baltic sea) by comparing winter with summer for the Arctic sea ice extension. For the polar vortex area on the Northern Hemisphere, in summer the polar vortex boundary withdraw about 30 latitudes than winter. In winter the center of the polar vortex locates about the north of pole, but in summer it shifts to the western hemisphere.3) Whatever in summer or in winter, it is evident that the inter-decadal variation of the Arctic sea ice and the 500hPa polar vortex area and intensity on the Northern Hemisphere. There are an obvious climatic trend on the Arctic sea ice area and the polar vortex area, while there is not a climatic trend on the polar vortex intensity. In winter, the time of sudden change of the polar vortex area is late about 10 years than that of the sea ice area, but in summer the time of sudden change of the polar vortex area is early about 15 years than that of the sea ice area.4) The Arctic sea ice area possessed the different oscillation period except the same oscillation period of 2-4a and 10a between in winter and in summer, and their period characteristic had changed after their sudden change. The winter polar vortex area and the summer polar vortex area have 4a period, while they have different period each other. The thing of the period on the winter polar vortex intensity and the summer polar vortex intensity is likely the thing of the polar vortex area.5) The EOF analysis of the polar vortex shows: the 500hPa polar vortex is obviously changing along with the changing of season.6) 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. In the long time, it is positive relative between the polar vortex area and intensity, it would bring about the expanding of the polar vortex area that the strengthening of the polar vortex because the strengthening of cool air would make the cool air to expand. In short time, the strengthening of the warm air on the southern of the Northern Hemisphere would compel the polarvortex area to shrink in near the pole region, yet the mass of cool air accumulating above the polar region would make the polar vortex strengthen. And it is also not a positive relative between the sea ice area and the polar vortex intensity, they are restricted by other physical factors too.7) Whatever in winter or in summer, for the Arctic sea ice area, the appearance frequency of light ice year is higher after sudden change than the before. This thing is obvious for the summer sea ice, and in the last years the seasonal different has extended.8) The study present, the reciprocity between the sea ice and the circumfluence of the polar vortex is more stronger in summer, and this make the summer sea ice become a more sensitive element of the climatic change on the Northern Hemisphere or on the whole globe.9) Whatever for winter or for summer, the polar vortexes has obvious different between in weight ice year and in light ice year, and those different are reflected by different meteorological elements from lower to h... |
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