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Nonlinear interactions between gravity waves and background winds
引用本文:Liu Xiao1,2 and Xu Jiyao1(1. State Key Laboratory for Space Weather,Center for Space Science and Applied Research,Chinese Academy of Sciences,Beijing 100080,China, 2. Graduate University of Chinese Academy of Sciences,Beijing 100039,China). Nonlinear interactions between gravity waves and background winds[J]. 自然科学进展(英文版), 2007, 17(6): 639-644
作者姓名:Liu Xiao1  2 and Xu Jiyao1(1. State Key Laboratory for Space Weather  Center for Space Science and Applied Research  Chinese Academy of Sciences  Beijing 100080  China   2. Graduate University of Chinese Academy of Sciences  Beijing 100039  China)
作者单位:1. State Key Laboratory for Space Weather,Center for Space Science and Applied Research,Chinese Academy of Sciences,Beijing 100080,China; 2. Graduate University of Chinese Academy of Sciences,Beijing 100039,China
基金项目:国家自然科学基金;国家重点基础研究发展计划(973计划)
摘    要:Using the nonlinear propagating gravity waves (GW) model in the two-dimensional compressible atmosphere and the linear GW theory, the process of GW propagation in different background winds, e.g. the direction of the background wind is opposite to (dead wind) or the same as (tail wind) the direction of the horizontal phase velocity of GW, is studied. The results show that the dead wind prolongs the vertical wavelength and accelerates GW propagation. Therefore, GW propagates up to a higher height becomes instable in a short time and eventually induces an inverse jet flow. Then, the vertical wavelength is becoming short due to the nonlinear interactions between GW and the inverse jet flow. The vertical wavelength and group velocity decrease after GW propagates into the tail wind. The initial instable time is delayed. Although most of GW is trapped in the instable region, some of GW propagates above the instable region. Compared with GW propagation in the tail wind, the nonlinear interactions between GW and the dead wind are also strong. In contrast, the linear GW theory predicts that GW can propagate freely in the dead wind. The vertical wavelength simulated by the nonlinear numerical model is different from that predicted by the linear theory greatly after GW propagates into the dead wind.


Nonlinear interactions between gravity waves and background winds
Liu Xiao,Xu Jiyao. Nonlinear interactions between gravity waves and background winds[J]. Progress in Natural Science, 2007, 17(6): 639-644
Authors:Liu Xiao  Xu Jiyao
Abstract:Using the nonlinear propagating gravity waves (GW) model in the two-dimensional compressible atmosphere and the linear GW theory, the process of GW propagation in different background winds, e.g. the direction of the background wind is opposite to (dead wind) or the same as (tail wind) the direction of the horizontal phase velocity of GW, is studied. The results show that the dead wind prolongs the vertical wavelength and accelerates GW propagation. Therefore, GW propagates up to a higher height becomes instable in a short time and eventually induces an inverse jet flow. Then, the vertical wavelength is becoming short due to the nonlinear interactions between GW and the inverse jet flow. The vertical wavelength and group velocity decrease after GW propagates into the tail wind. The initial instable time is delayed. Although most of GW is trapped in the instable region, some of GW propagates above the instable region. Compared with GW propagation in the tail wind, the nonlinear interactions between GW and the dead wind are also strong. In contrast, the linear GW theory predicts that GW can propagate freely in the dead wind. The vertical wavelength simulated by the nonlinear numerical model is different from that predicted by the linear theory greatly after GW propagates into the dead wind.
Keywords:gravity waves  background winds  vertical group velocity  vertical wavelength  nonlinear interactions
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