| 我国前冬和后冬的划分及其气温的年际变异 |
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| 引用本文： | 韦玮,王林,陈权亮,刘毓赟,李珍.我国前冬和后冬的划分及其气温的年际变异[J].大气科学,2020,44(1):122-137. |
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| 作者姓名： | 韦玮 王林 陈权亮 刘毓赟 李珍 |
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| 作者单位： | 1.成都市气象局 |
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| 基金项目： | 国家重点研究发展计划项目
2018YFC1506003
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国家自然科学基金项目
41721004
;
中国科学院前沿科学重点项目
QYZDY-SSW-DQC024
国家重点研究发展计划项目2018YFC1506003,国家自然科学基金项目41721004,中国科学院前沿科学重点项目QYZDY-SSW-DQC024 |
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| 摘 要： | 基于我国762站均一化逐日平均和逐日最低气温数据集,对我国年最低气温的概率密度分布的分析表明,我国年最低气温的概率密度呈现清晰的双峰分布特征。进一步考察其原因发现东亚冬季风盛行期间我国年最低气温的分布具有显著的地域性差异,以冬季气候态气温的0℃为界大致可以分为两种气候区。综合不同气候区内年最低气温所在日期的概率密度分布的结果,将11月16日至次年1月15日划分为前冬,次年1月16日至3月15日划分为后冬。在此基础上,通过依赖于季节的经验正交函数分解方法分析了近56年我国前冬和后冬气温在年际变异上的特征,并进一步利用NCEP/NCAR全球日平均再分析资料通过合成分析的方法研究了其对应的大气定常波和瞬变波特征。结果表明:年际变化时间尺度上,我国前冬和后冬气温演变仍表现为前、后冬同相演变和反相演变这两个主要模态。同相演变模态环流异常的空间形态在前冬和后冬较为一致,并随着前冬向后冬的推移其环流异常的强度在不断加强;反相演变模态则对应了环流异常在前冬和后冬的相反变化,且其环流异常的空间形态在前冬和后冬有较大不同。对大气波动特征的分析表明,瞬变波的动力和热力的强迫作用以及定常波能量向下游的频散对北大西洋至欧亚大陆上定常波列的维持和发展具有重要作用。同相演变模态中,北大西洋上的波列将能量从北美向欧洲地区传播,加强了后冬欧洲地区的高压异常,该中心在后冬向下游的能量频散显著增强,形成了一个自欧洲经喀拉海以东至贝加尔湖附近的定常波列,大气瞬变波所引起的动力和热力强迫对该波列位于欧洲和贝加尔湖地区的大气活动中心的维持和发展具有正的贡献。反相演变模态中前冬的波动特征与同相演变模态后冬基本一致,而后冬则表现为从北大西洋中部向格陵兰岛传播,并进一步向东经乌拉尔山附近传向青藏高原北部的波列,风暴轴移动所引起的大气瞬变波的动力和热力强迫对该波列位于北大西洋地区南侧的中心有维持作用。
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| 关 键 词： | 前冬 后冬 同相演变 反相演变 定常波 瞬变波 |
| 收稿时间： | 2018/10/9 0:00:00 |
Definition of Early and Late Winter and Associated Interannual Variations of Surface Air Temperature in China |
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| WEI Wei,WANG Lin,CHEN Quanliang,LIU Yuyun,LI Zhen.Definition of Early and Late Winter and Associated Interannual Variations of Surface Air Temperature in China[J].Chinese Journal of Atmospheric Sciences,2020,44(1):122-137. |
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| Authors: | WEI Wei WANG Lin CHEN Quanliang LIU Yuyun LI Zhen |
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| Institution: | 1.Chengdu Meteorological Bureau, Chengdu 611130;2.Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;3.Plateau Atmosphere and Environment Key Laboratory of Sichuan Province/School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 610225;4.Key Laboratory of Regional Climate-Environment in Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | Based on daily mean air temperature(Tm)and daily minimum air temperature(Tmin)data from 762 Chinese stations,analysis of the probability density distribution of annual minimum air temperature in China showed a clear bimodal distribution.It was found that there are significant regional differences in the distribution of annual minimum air temperature during the East Asian winter monsoon.Inspections of the spatial distribution of the frequency of annual minimum air temperature in the two peaks revealed significant regional differences,which were roughly divided into two climatic zones by the 0℃line of the long-term mean winter air temperature.By analyzing the date of annual minimum air temperature in the two climatic zones,the boreal winter was divided into an early winter that spans from November 16th to January 15th of the following year,and a late winter that spans from January 16th to March 15th.Following this definition,the interannual variations of early and late winter air temperatures in China were studied by season-reliant empirical orthogonal function(SEOF).Meanwhile,the associated atmospheric stationary and transient waves and their interactions were analyzed based on the National Centers for Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR)reanalysis data.It revealed that the first two SEOF modes of surface air temperature from early to late winter depicted the in-phase evolution and the out-of-phase evolution.The spatial morphology of the atmospheric circulation anomaly in early and late winter in the in-phase evolution mode is relatively consistent,and intensity of the circulation anomalies strengthens gradually from early to late winter.However,the atmospheric circulation anomaly in early and late winter in the out-of-phase evolution mode is quite different,as is their spatial morphology.Dynamic and thermal forcing effects of transient waves and the dispersion of the stationary waves play an important role in the maintenance and development of stationary waves from North Atlantic to Eurasia.Waves on the North Atlantic in the inphase evolution mode spread energy from North America to Europe,which strengthens the European high.Energy dispersions of this center are significantly enhanced in late winter,which forms the wave from Europe to the east of the Kara Sea and further to Lake Baikal.Dynamic and thermal forcing effects caused by atmospheric transient waves make a positive contribution to the maintenance and development of the atmospheric centers of action in Europe and the Baikal area.Characteristics of atmospheric stationary and transient waves and their interactions in early winter in the out-of-phase evolution mode are similar to those in late winter in the in-phase evolution mode.However,the waves in late winter spread from the center of the North Atlantic to Greenland,and further eastward through the Ural region to the northern part of the Tibetan Plateau.Movement of the storm track can lead to abnormal activities of the transient waves,making a positive contribution to the maintenance of the atmospheric centers of action in the southern North Atlantic. |
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| Keywords: | Early winter Late winter In-phase evolution Out-of-phase evolution Stationary waves Transient waves |
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