陈宪,钟中,卢伟,孙源.东亚副热带高空急流短时间尺度增强的机理研究.气象科学,2018,(6):790-797 CHEN Xian,ZHONG Zhong,LU Wei,SUN Yuan.Study on the mechanism of short-time scale increase of the East Asian subtropical upper-level jet stream.Journal of the Meteorological Sciences,2018,(6):790-797
东亚副热带高空急流短时间尺度增强的机理研究
Study on the mechanism of short-time scale increase of the East Asian subtropical upper-level jet stream
投稿时间:2017-10-20  修订日期:2017-11-13
DOI:10.3969/2017jms.0084
中文关键词:  东亚副热带高空急流  短时间尺度增强  数值模拟  大气运动方程
英文关键词:East Asian subtropical upper-level jet  Short-time intensification  Numerical simulation  Atmospheric motion equation
基金项目:国家自然科学基金资助项目(41430426,41605072);公益性行业(气象)专项资助项目(GYHY201306025)
作者单位E-mail
陈宪 国防科技大学 气象海洋学院, 南京 211101
中国空气动力研究与发展中心计算空气动力研究所, 四川 绵阳 621000 
 
钟中 国防科技大学 气象海洋学院, 南京 211101
江苏省气候变化协同创新中心 南京大学, 南京 210023 
zhong_zhong@yeah.net 
卢伟 国防科技大学 气象海洋学院, 南京 211101  
孙源 国防科技大学 气象海洋学院, 南京 211101  
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中文摘要:
      本文利用中尺度非静力模式WRF输出的高时空分辨率模拟资料研究了东亚副热带高空急流(EASJ)短时间尺度强度变化特征,并结合大气运动方程解释了EASJ增强的可能机制。结果表明,在6 h时间间隔内,急流区纬向风增量的水平尺度大于2 000 km。急流轴北侧高频扰动较少,南侧出现大量高频扰动,相应地,急流轴北侧纬向风大尺度整体增强,而急流轴南侧纬向风增量正值区中还存在水平尺度为几百公里的负值区。高频扰动的周期约为1~6 h,向东传播速度为20~40 m·s-1,与惯性重力波相似。造成EASJ短时间尺度增强的主要物理因子为水平平流作用和非地转效应。水平平流项和非地转项量级相同,但变化趋势几乎相反。两者之和的量值与纬向风局地加速度项相近。此外,垂直平流作用对EASJ强度变化也有一定贡献。
英文摘要:
      In this paper, the characteristics of the short-time scale variation of the East Asian Subtropical Upper-level Jet Stream (EASJ) were studied by use of the high spatial-temporal resolution simulation data output of the nonhydrostatic mesoscale model WRF. The possible mechanism for the EASJ intensification is explained in light of the atmospheric motion equation. The results indicate that the horizontal scale of zonal wind increment is greater than 2 000 km in the 6 h time interval. Few high-frequency disturbances occur to the north side of EASJ axis, while many occur to the south. Correspondingly, the intensity of zonal wind on the north side of the EASJ axis increases in a large scale, while a negative value area with a horizontal scale of several hundred kilometers still exits in the positive value area of zonal wind increment on the south side of the EASJ axis. The period of high frequency disturbance is about 1-6 h, and the eastward propagation speed is 20-40 m·s-1, which is similar with that of the inertial gravity wave. The main physical factors that contribute to the short-term scale increase of EASJ are horizontal advection and ageostrophic effects. The magnitude of the horizontal advection term is the same as that of the ageostrophic term. However, the variation trends of those two factors are basically opposite. The magnitude of the sum of the two is similar to the local acceleration term of the zonal wind. In addition, the vertical advection also contributes to the change in EASJ intensity.
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