1980-2000年北极平流层冬季十年际变化形势的逐月演变
投稿时间:2019-11-14  修订日期:2020-02-13  点此下载全文
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作者单位E-mail
刘仁强 南京信息工程大学 rq_liu@nuist.edu.cn 
吴国华 南京信息工程大学  
黎颖 汉中市气象局  
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:采用1980-2000年的ERA-Interim再分析资料,计算北半球冬季各月(12月、1月、2月)行星波的Eliassen-Palm(EP)通量及其散度,并按冬季不同月份分析平流层整层温度和纬向风场的十年际变化特征与行星波活动变化的关系。结果表明,温度的十年际变化在高纬度中下平流层12月呈明显增温趋势,1月转为较弱的冷却趋势,而2月为明显的冷却趋势。纬向风在中高纬平流层12月呈明显的减速变化,1月减速区与加速区相间分布但强度均较弱,而2月为明显的加速趋势。12月行星波沿低纬度波导向热带对流层顶的传播减弱,沿极地波导向平流层整层的传播明显加强;1月沿两支波导的传播趋势未变但均较弱;而2月行星波沿低纬度波导的传播转为加强趋势,沿极地波导的传播转为减弱趋势。相应地,EP通量散度场的十年际变化形势沿两支波导在12月与2月相反,1月为过渡阶段。因此,北极平流层温度、纬向风、EP通量及其散度场的十年际变化在冬季内呈现一个从北半球环状模(Northern Hemisphere Annular Mode, NAM)的负极趋势向正极趋势逐月演变的过程。
中文关键词:平流层  十年际变化  温度  纬向风  行星波活动
 
Winter Month-to-Month Evolution of Decadal Changes in the Arctic Stratosphere during 1980-2000
Abstract:In this study, the Eliassen-Palm (EP) flux and its divergence of the planetary wave in the Northern Hemisphere winter (December—February) are calculated by using the ERA-Interim reanalysis data from 1980—2000. Then the characteristics of decadal changes in the whole layer of stratospheric temperature and zonal wind and the relationships to changes in planetary wave activity during different winter months are analyzed respectively. The results indicate that the temperature decadal changes show a significant warming tendency in the high-latitude middle and lower stratosphere in December, while turning into a weak cooling tendency in January, and an obvious cooling tendency in February. The zonal winds show a significant deceleration in the mid-to-high latitude stratosphere in December, and the deceleration and acceleration zones are distributed alternately with weak intensity in January, but a significant acceleration for February. The planetary waves propagate into the tropical tropopause along the low-latitude waveguide weakens whereas that along the polar waveguide into the stratosphere strengthens significantly during December. The propagations along two waveguides are unchanged but the intensities both decrease in January. As for February, it turns into an evident strengthened tendency along the low-latitude wave guide and an obvious weakened tendency along the polar wave guide. Meanwhile, the decadal changes of the EP flux divergence are opposite in December and February, and January is a transitional period. Therefore, the decadal changes of the Arctic stratospheric temperature, zonal winds, EP flux and its divergence present a month-to-month evolution from the NAM (Northern Hemisphere Annular Mode) index negative polarity tendency to the positive polarity tendency throughout the winter.
keywords:stratosphere  decadal changes  temperature  zonal wind  planetary wave activity
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