Barotropic local instability and severe storm process

作     者：杨大升 孙岚 

作者机构：Department of Geophysics Peking University Beijing 100871 China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：1997年第40卷第3期

页      面：259-268页

核心收录：

学科分类：07[理学] 070601[理学-气象学] 0706[理学-大气科学] 

基　　金：Project supported by the National Natural Science Foundation of China 

主　　题：eigen and initial value problems of truncated spectral equation local unstable evolution interaction of wave system 

摘      要：By means of barotropic model, the characteristic and initial value problems are investigated to reveal the local two-dimensional barotropic instability of the nonuniform current to the dynamic mechanism of the formation of the Yangtze-Huaihe River severe storm in July 1991. Analytical theory and numerical experiment show that (i) the unstable developing modes are chiefly the two periods of about 44d and 10 d, which are fundamentally consistent with that of the precipitation change of the Yangtze-Huaihe River, (ii) The growth rate of the local perturbation is dominated by the meridional wave number n = 1-5 and zonal wave number k = 1-12, i.e. the severe storm over the Yangtze-Huaihe River results from the interaction of the systems at different latitudes and waves of different scales, (iii) The perturbation over the Yangtze-Huaihe River possesses the property of local intensification, which slowly migrates westward over the lower and middle reaches of the Yangtze-Huaihe River, (iv) The growth rate of the instability, especially the propagation velocity of the perturbation, is sensitive to the external parameters -u and a.