2003～2004年冬季平流层爆发性增温动力诊断分析

利用逐日的欧洲中尺度天气预报中心(ECMWF)60层模式资料, 对2003年12月～2004年2月期间发生的一次非典型的爆发性增温中平流层结构的变化过程进行动力学诊断分析。充分利用资料层次高(最高层为0.1 hPa)和垂直分辨率高(垂直方向共60层)的优势, 通过对不同高度等熵面位涡分布的分析, 研究了极涡在平流层爆发性增温(SSW)发生前后的变化发展; 通过对EP通量及其散度的分析, 研究了SSW过程中行星波的变化特点; 通过对剩余环流的分析, 研究了在SSW过程中经圈环流的变化及其对动力过程的影响。得出: (1) 2003/2004年SSW增温过程持续时间长、强度大; (2) 增温最早发生在平流层上层并向下传播, 在10 hPa形成较强东风带后, 上层西风环流迅速恢复, 极涡再度形成, 下层则增温持续; (3) SSW前后行星波活动频繁, 有长时间多次的上传, 且以1波作用为主, 2波对其进行了补充; (4) 在SSW过程前后, 平流层中的剩余环流发生反转, 影响了平流层中、 高纬地区和低纬地区的物质交换以及上下层物质的重新分配。这一系列的工作为今后进一步研究平流层、 对流层交换, 发展完善气候模式打下基础。

A Dynamical Diagnosis of Stratospheric Sudden Warming in 2003-2004 Winter

The dynamical characteristics of an intense stratospheric sudden warming occurring from December 2003 to February 2004 are diagnosed by using the ECWMF daily data. Due to the higher pressure levels and vertical resolution, the evolution of polar vortex is investigated by analyzing the distribution of isentropic potential vorticity at different levels; the activities of planetary wave are explained by studying the Eliassen-Palm (EP) flux and its divergence, and the variation of meridional circulation and its impact on chemical transport are researched by analyzing the residual mean circulation. The results show that: (1) This stratospheric sudden warming (SSW) event has a long and intense process.(2) The earliest warming broke out in the higher stratosphere, then spread down to lower layer. The upper westerlies and vortex recovered promptly after the generation of easterlies at 10 hPa, while the lower stratosphere continued warming.(3) The planetary wave is so active that it propagated from the troposphere to the stratosphere several times, and the wave number 1 played a major role.(4) The residual circulation in the stratosphere reversed after SSW, inducing the alternation of transmission between high and low latitudes and distribution at different vertical levels. These results will lay the foundation for advanced investigation in the Stratospheric-Tropospheric Exchange (STE) and further development of GCM study.