Radar observation and model computation of a jet stream‐generated Kelvin‐Helmholtz instability
Radar observation and model computation of a jet stream‐generated Kelvin‐Helmholtz instability
复制标题
急流产生的开尔文-亥姆霍兹不稳定性的雷达观测和模型计算
DOI：
10.1029/jc085ic05p02841
复制
发表时间：
1980
影响因子：
--
通讯作者：
R. Rüster
中科院分区：
文献类型：
--
作者：
J. Klostermeyer;R. Rüster
位于德国哈尔茨山的SOUSY VHF雷达记录了极锋急流通过时的一个风分量和雷达回波功率。测量是在对流层进行的，高度和时间分辨率分别为150米和10秒。在喷流的低剪切区，出现了周期接近4 min的开尔文-亥姆霍兹不稳定性（Kelvin-Helmholtz instability，KHI），速度幅值约为1 m s−1。在生长阶段的KHI的回声功率显着增加，并保持强劲，即使在KHI已经消失。它的结论是，产生增强的回波功率的3米湍流结构的一部分，开始与4分钟KHI的产生的广泛的不稳定性。所观察到的KHI的属性进行了比较与增长最快的不稳定性计算的线性业务模型考虑到垂直廓线的平均风和温度，从雷达和无线电探空仪上升。计算的频率，增长率，和速度分布显示出良好的定性，部分，甚至定量与观测结果一致。
During the passage of a polar front jet stream, one wind component and the radar echo power were recorded by the SOUSY VHF radar located in the Harz Mountains in Germany. The measurements were performed in the troposphere with height and time resolutions of 150 m arid 10 s, respectively. In the lower shear region of the jet stream a Kelvin-Helmholtz instability (KHI) occurred with a period near 4 min and velocity amplitudes of the order of l m s−1. During the growth stage of the KHI the echo power increased significantly and remained strong even after the KHI had disappeared. It is concluded that a 3-m turbulence structure which produced the enhanced echo power is part of a broad spectrum of instabilities which started with the generation of the 4-min KHI. The properties of the observed KHI are compared with those of the fastest growing instability computed from a linear operational model taking into account vertical profiles of the mean wind and temperature which were obtained from the radar and a radiosonde ascent. The computed frequency, growth rate, and velocity profile show excellent qualitative and, partly, even quantitative agreement with the observational results.