摘要
在 Dole持续异常界定方法的基础上提出了一种适用于全球分析的界定方法 ,并利用NCEP/NCAR 1 980～ 1 998年 6月 1日～ 8月 31日逐日再分析资料 ,分析了全球大气环流持续异常的分布 ,重点研究了乌拉尔地区反复出现的、维持较长时间的强环流异常的背景流及其演变特征 ,得到以下结论 :1 )文中提出的界定方法能较好地识别全球地区持续异常分布 ;2 )乌拉尔地区环流正、负持续异常形成时 ,背景环流的发展不具有对称性 ,负异常并不是正异常的简单相反过程。正异常的发展与位于西南方的正距平扰动向东北移动、及与位于中西伯里亚的正距平扰动西移有关 ,这些扰动具有相当正压结构的 ,而负异常则主要是局地发展而形成的 ;3)正压过程对乌拉尔持续异常的形成起着主要作用 ,明显不同于北太平洋环流持续异常的发展 ;4)乌拉尔正、负持续异常期间的背景流不仅在北半球中高纬有明显差异 ,而且在南、北半球其它地区也有明显差异 ,热带的差异在低频环流上表现得更为清楚 ;5)在异常发生前 ,中纬度急流已发生了有利于异常建立的改变。
A definition method of persistent anomaly(PA in brief) is proposed based on Dole(1983), and it can be used for global analysis of anomaly circulation. The global distribution of PA is calculated by use of Re analysis data of NCEP/NCAR(Jun.1 to Aug.31, 1980-1998) and the characteristics and evolution of background circulation of the PA over Ural area, which have long duration and maybe emerge repeatedly, are studied specially. It is concluded: (1) The definition method of PA proposed in this paper is suitable to analyze global PA;(2)Positive/Negative PA background circulation and their development have no symmetry, the development process of negative PA is not contrary to positive PA simply. The development of +PA is related to the movement to northeast of perturbation and to the westward movement of positive anomaly over mid Siberia , which have equivalent barotropic structure and will merge as to the setup of +PA over Ural, while-PA results mainly from the development of local negative anomaly over Ural; (3)Barotropic process may be plays an important role in formation of PA, as is evidently different from PA over north Pacific;(4)There exists obvious difference not only in mid latitudes of Northern Hemisphere, but also in tropics, high latitudes and polar area of bi Hemisphere. (5)Upper Jet in mid latitudes is benefit to the setup of PA before PA begins.
出处
《气象学报》
CSCD
北大核心
2001年第3期280-293,共14页
Acta Meteorologica Sinica
基金
国家自然科学基金 ( 497752 61 )
优秀国家重点实验室研究项目 ( 4982 30 0 2 )
<国家重大基础研究发展规划>G1 9980 4 0 90 0项目
