杨莲梅,张庆云. 2014. 一次中亚低涡中期过程的能量学特征[J]. 气象学报, 72(1):182-190, doi:10.11676/qxxb2014.002
一次中亚低涡中期过程的能量学特征
Energetic characteristics of a medium-range process of Central Asian vortex
投稿时间:2013-03-04  修订日期:2013-09-22
DOI:10.11676/qxxb2014.002
中文关键词:  中亚低涡  能量循环  能量收支  扰动动能
英文关键词:Central Asian vortex  Energy cycle  Energy budget  Eddy kinetic energy
基金项目:国家自然科学基金项目(41075049);国家重点基础研究发展计划项目(2010CB951001);国家科技支撑项目(2012BAC23B01)。
作者单位
杨莲梅 新疆维吾尔自治区气象台, 乌鲁木齐, 830002
中国气象局乌鲁木齐沙漠气象研究所, 乌鲁木齐, 830002 
张庆云 中国科学院大气物理研究所, 北京, 100029 
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中文摘要:
      中亚低涡是中期时间尺度(4天以上)的对流层深厚切断低压系统,也是造成新疆暴雨(雪)、持续低温天气的重要影响系统之一,对其形成、维持和减弱的能量特征还不十分清楚。利用美国国家环境预报中心/国家大气研究中心(NCEP/NCAR)2.5°×2.5°逐日再分析资料和有限区域能量循环方程,对1996年7月10—20日造成新疆区域两次暴雨过程的中亚低涡系统进行分析,以揭示低涡持续活动11天的能量循环和转换特征。分析结果表明,中亚低涡活动具有明显的阶段性能量学特征。这次低涡发展和减弱过程处于斜压不稳定状态,扰动动能来源于扰动位能的转换和区域开放边界扰动动能的输入,且两者作用相当,它们使得低涡快速发展,同时区域内部非绝热加热制造的一部分扰动有效位能向外输出,在减弱期扰动有效位能向外输出大于扰动位能的转换和区域开放边界扰动动能的输入,因此低涡逐渐减弱。低涡成熟期处于正压不稳定状态,系统内部的能量转换很小,扰动动能来自于外界扰动位能输入,支出项为向开放边界的扰动动能输出。低涡过程各个时期纬向平均动能向扰动动能的转换都很小,即正压不稳定造成的能量转换较弱。低涡活动过程中,在对流层中、高层扰动动能很强,表明中亚低涡是主要在对流层中、高层活动的天气尺度系统,低涡内部的能量转换及其与外界的能量输送主要发生在中、高层,扰动位能和扰动动能的变化很好地反映低涡的强度变化和发展阶段,且能量的垂直输送对低涡系统的发展也有一定促进作用。
英文摘要:
      A Central Asian vortex (CAV) of medium-range time scale (over 4 days) is a deep cutoff low in the troposphere, and it is also one of the important influence systems which cause rainstorm, snowstorm and persisting low-temperature in the Xinjiang region. But the energetic characteristics at its formation, maintenance and mature stage are not clear. Energetic characteristics of the medium-range process of CAV during 10-20 July 1996, which caused 2 rainstorm processes in Xinjiang, are investigated using the NCAR/NCEP daily 2.5°×2.5° reanalysis data and the energy cycle equations for open atmospheric region. The results show that distinct features exist for the different periods. This vortex is always getting along with baroclinic instability conditions during either the developing and weakening process. The conversion term from eddy available potential energy (AE) to eddy kinetic energy (KE) and the eddy kinetic energy inflow (BKE) from open atmospheric region boundaries act as main sources of the KE, and they play an equivalent role in bring about the rapid development of vortex, and at the same time a part of eddy available potential energy by the diabatic heating (RE) exports. Since RE is more than AE→KE and BKE, it causes vortex to weaken during the weakening stage. The vortex keeps barotropic instability conditions with weak energy conversions within vortex during its mature stage, and the source and sink of KE is eddy available potential energy import from environment and eddy kinetic energy outflow, respectively. During the every stages the conversion term from the zonal kinetic energy (KZ) to KE is very weak, suggesting that energy conversion from barotropic instability is rather little. KE is quite strong at the middle and upper troposphere, implying that the Central Asian vortex mainly exists about over 700 hPa. Energy conversion within the vortex and energy transportation with environment mostly take place over 700 hPa. AE and KE variation can primely manifest intensity change and the developing stage of vortex. Energy vertical transportation promotes the vortex development to a certain degree.
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