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为了探讨强极涡与La Ni?a事件之间的关系,利用NCEP/NCAR(日平均、月平均位势高度及温度场)再分析资料对2010—2011年冬季进行个例研究。与气候态相比,2010—2011年冬季北半球平流层极涡偏强,同时,显著的强海温负异常(La Ni?a事件)也持续整个冬季。结果表明,受La Ni?a事件影响,对流层环流场和温度场得到较大的调整,出现PNA(Pacific North American)型异常环流形势和相对应的温度异常分布。2010年12月,阿留申地区出现负值的热量经向输送,使得该地区从对流层上升至平流层的行星波动与气候态相比明显减弱,从而导致平流层极涡较气候平均态偏强。这一La Ni?a事件对平流层极涡影响的动力过程也从1948—2010年期间选出的13个冬季强La Ni?a事件的合成分析结果中得到证实。
In order to investigate the relationship between strong vortices and La Niña events, a case study of the 2010-2011 winter season was conducted using NCEP / NCAR (daily average, monthly mean geopotential height and temperature field) reanalysis data. Compared with the climatological state, the polar stratosphere in the northern hemisphere of 2010-2011 is more intense in winter and the significant negative anomalies of the sea surface temperature (La Niña) also persist throughout the winter. The results show that due to the influence of La Ni? A, the circulation field and the temperature field in the troposphere are greatly adjusted, and the abnormal North Atlantic (PNA) circulation and corresponding temperature anomalies occur. In December 2010, negative Alejandro thermal convection occurred in the Aleutian region, resulting in a marked decrease in planetary fluctuations from the troposphere to the stratosphere compared with the climatological state, resulting in a stronger stratospheric polar vortex than the climatological average. The dynamics of the influence of this La Niña event on the stratospheric polar vortex are also confirmed by the synthetic analysis of 13 winter strong La Niña events selected during 1948-2010.