热带东风急流显著偏强和偏弱期平流层绕极反气旋及波动的差异

DIFFERENCES OF STRATOSPHERIC ANTICYCLONE CENTERED ON NORTH POLE AND WAVE MOTION BETWEEN SPECIALLY STRONG AND WEAK TROPICAL EASTERLY JET PERIODS

首先采用150～100 hPa气层20°W～180°,15°S～35°N区域的平均东风和单位面积东风贡献的动能两种办法定义了热带东风急流(TEJ)指数,并分析了1948—2010年TEJ随时间的变化。然后利用谐波分析方法分析了急流显著偏强和偏弱期平流层10 hPa绕极反气旋和波动的差异。分析表明,在急流显著偏强期平流层10 hPa 40°N以北的绕极反气旋偏弱,而急流显著偏弱期则偏强,差值约为100～150位势米。45°N以北1波占绝对优势,1波从春到夏的季节转换与TEJ的快速发展紧密相连,急流显著偏强期1波的季节性调整早于显著偏弱期。急流显著偏强和偏弱期相比,极区65～85°N 1波平均槽脊位置有较大差异。45～60°N纬带1波在急流显著偏强期振幅明显加强,变化相对稳定,而急流显著偏弱期1波振幅和位相的变化要强烈得多。

First, the tropical easterly jet （TEJ） index is defined using two methods, the mean easterly and the unit area of kinetic energy contributed by the easterly, which are averaged for 150 hPa and 100 hPa over 20 °W～180°, 15 °S-35°N. Then, the change of TEJ from 1948 to 2010 is analyzed. In the end, the differences of a stratospheric anticyclone centered on the North Pole at 10hPa and planetary waves between specially strong and weak TEJ periods are studied through harmonic analysis. The results show that the anticyclone north of 40°N is weaker in the specially strong TEJ period than that in the specially weak TEJ period, the geopotential height difference between the two TEJ periods is 100 - 150 geopotential meters. The planetary wave of wave number 1 has absolute predominance north of 45 °N, the seasonal adjustment from spring to summer in the planetary wave of wave number 1 is interrelated with rapid development of TEJ, and the seasonal adjustment of wave number 1 is earlier in the specially strong TEJ period. The localities of trough and ridge of wave number 1 over 65 - 80°N are much different in the specially strong and weak TEJ periods. The wave number 1 over 45 -60°N is much stronger in the specially strong TEJ period than that in the specially weak TEJ period. The change of wave number 1 is relatively stable in the specially strong TEJ period, but it is far more intense in the specially weak TEJ period.