北半球不同强度、生命期阻塞高压的变化特征及其对温度的影响

Variation characteristics of different atmospheric blockings and their impact on temperature over the Northern Hemisphere

分析了1968-2010年北半球阻塞高压频发区不同强度、生命期阻高的变化特征,从阻高强度和阻高生命期两方面分析阻高多发年、少发年与北半球地表温度的关系,结果显示:北半球的3个阻高频发区中,大西洋地区阻高出现总次数最多,太平洋地区次之,欧亚区最少;从阻高强度来看,3个阻高频发区强阻高次数均有减少趋势,以大西洋区最为显著,弱强度阻高变化趋势不明显;对于阻高生命期,长生命期阻高发生次数在21世纪以前变化不大,但近10年增加明显,短生命期阻高发生次数只有大西洋区在减少.大西洋区强阻高中长生命期阻高占25%,而太平洋区仅为14%,阻高强度越强时,出现长生命期阻高的概率也就越大.不同强度、生命期阻高对温度的影响差异显著.3个阻高频发区的长生命期阻高多发年与少发年温度差值的负异常区主要分布在中低纬度地区,而正异常区主要在高纬度地区;大西洋区、太平洋区长生命期阻高在多发年引起中低纬度地区的降温及高纬度地区的增温比强阻高产生的影响显著.

The variation characteristics of different atmospheric blocking intensities and durations and their impact on surface temperature in years of 1968—2010 were analyzed for the three regions of Northern Hemisphere（NH）where blocking highs occur frequently（Atlantic,Pacific and Eurasian regions）.The results show that the blocking frequency of the Atlantic was the highest in the three regions of NH,while that of the Eurasian was the lowest.From the aspect of blocking intensity it was revealed that the strong blockings all exhibited a decreasing trend over the three regions,especially in the Atlantic,and there were a slightly upward tendency for weak blockings.The increasing trend for long-duration（≥13 days） blocking was insignificant in 1968—2000 for the three regions,but it has presented a remarkable increase since 2000.A decrease of short-duration blocking frequency was only found in the Atlantic region.Long-duration blockings contribute 25%to the strong blockings in the Atlantic region,whilst 14%to the Pacific blocking region,and it was found that the increasing probability was accompanied by the enhanced intensity of blockings.Different blocking intensities and durations yielded significant differences in temperature.Negative anomaly of the temperature differences between the more long-duration blocking years and the fewer long-duration blocking years were mainly in the mid-low latitude regions,while high latitude areas showed a positive anomaly temperature.Compared with strong blockings,the impact of long duration blockings on temperature was remarkable over the Atlantic and Pacific regions.