20世纪70年代末前后北半球冬季对流层遥相关的时空演变研究

应用NOAA提供的1950～2008年月平均500 hPa高度场再分析资料、海表温度、太平洋年代际振荡(PDO)指数和大西洋三极模(ATM)指数, 研究了20世纪70年代末前后北半球冬季对流层遥相关的时空演变规律。相关分析、Mann-Kendall分析和凝聚小波分析的结果表明, 20世纪70年代末以来, 太平洋—北美(PNA)型、欧亚(EUP)型、西太平洋(WP)型和西大西洋(WA)型四种遥相关空间分布和时间演变产生较为显著的变化。空间分布的变化既体现在遥相关正、负异常中心的强度上, 也体现在正、负异常的范围上; 时间演变方面的变化则体现在PNA和WP遥相关指数具有上升趋势, EUP和WA遥相关指数具有一定下降趋势。20世纪70年代末以来, 影响北半球冬季5种遥相关型的海温关键区均有所改变。其中, 各大洋上影响EUP遥相关型的海温关键区面积显著缩小, 影响WA遥相关型的太平洋海温关键区面积显著缩小, 影响EA遥相关型海温关键区在北大西洋中南部改变明显; 在16年以上时间尺度上, PDO变化是造成北半球冬季PNA、 EUP、 WP三种遥相关型变化的主要原因; ATM变化是造成北半球冬季WA和EA两种遥相关型变化的主要原因。

Temporal and Spatial Evolution of Teleconnection in the Troposphere during the Northern Hemisphere Winter at the End of the 1970s

Using the NOAA monthly reanalysis geopotential height on 500 hPa, the sea surface temperature (SST), the Pacific decadal oscillation (PDO) index and the triple mode of North Atlantic SST anomaly (ATM)index from 1950 to 2008, the temporal and spatial evolution of teleconnection in the troposphere during the Northern Hemisphere winter at the end of the 1970s is studied with correlation analysis method, Mann-Kendall analysis method, and coherence wavelet analysis method. The results indicate that the spatial distributions and temporal evolutions of Pacific-North American (PNA), Eurasia-Pacific (EUP), West Pacific (WP), and West Atlantic (WA) teleconnection patterns change significantly at the end of the 1970s. The spatial distribution changes are found in the intensity and range of abnormal centers of these teleconnection patterns. On temporal evolution, the upward tendency of PNA and WP indexes and the downward tendency of EUP and WA indexes are also found. After the end of the 1970s, the key SST areas impacting on the 5 teleconnection patterns during the Northern Hemisphere winter have changed, in which those areas impacting on the EUP, and those areas in the Pacific impacting on WA have significantly decreased; those areas in the middle and southern Atlantic impacting on EA have obviously changed. On the time scale above 16 years, the variation of PDO is the main reason which leads to the variation of PNA, EUP, WP, and WA teleconnection patterns; the variation of ATM is the main reason which leads to the variation of WA and EA teleconnection patterns during the Northern Hemisphere winter.