北半球冬季极涡异常变化的时空特征
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公益性行业科研专项(GYHY201006020)


Spatial-temporal variations of polar vortex anomaly over Northern Hemisphere in winter
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    摘要:

    利用NCEP/NCAR再分析月平均高度场资料,计算了1948/1949-2009/2010年北半球冬季500~10 hPa的极涡环流指数,包括面积指数S、强度指数P和中心位置指数(λcc)。分析了北半球冬季极涡在垂直高度上(共12层)的季、月气候态和异常态变化规律。结果表明:极涡面积和强度在不同高度上的大小变化不同,最大值出现的时间也存在差异,二者相关性不好,为两个相对独立的指数。极涡面积和强度的年代际变化趋势在上下层上也不一样,异常变化规律复杂;极涡中心位置上下层变化规律相同,主要在东半球80°N以北范围变化,在极点附近经度变化大,纬度变化小,纬度指数年代际变化明显,近10 a极涡明显偏南。从整体上看,极涡中心位置从500 hPa到10 hPa形态上为逆时针、半径越向上越大的旋转变化。

    Abstract:

    Based on the NCEP/NCAR reanalysis monthly height data from 500 to 10 hPa(total 12 layers) in winter from 1948/1949 to 2009/2010,three polar vortex circulation indices of Northern Hemisphere are calaulated,which are the area index(S),the strength index(P),and the center position index(λcc) including longitude and latitude.The vertically seasonal,monthly and abnormal changes of Northern Hemisphere polar vortex are analyzed.Results show that the changes of polar vortex area and strength are different not only in the different heights,but also in the appearance time of the intraseasonal maximum.Correlation between the polar vortex area and strength is not significant,therefore they can be seemed as two independent indices.There are also differences of the area and strength interdecadal trends between in the upper layer and in the lower layer,and their abnormal changes are complicated.The changes of the center positions in both the upper and lower layers are identical.The changes are mainly located in the north of 80°N of the eastern hemisphere.Around the North Pole,the polar vortex longitude change is much more severe than the latitude change.The interdecadal change of latitude is significant,and the polar vortex is obviously southward in recent 10 years.On the whole,the position of polar vortex center from 500 hPa to 10 hPa varys in counterclockwise direction,and the radius increases with height.

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  • 收稿日期:2011-03-19
  • 最后修改日期:2012-08-14
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