%0 Journal Article
%T Properties and Stability of a Meso-Scale Line-Form Disturbance
%A SHEN Xinyong
%A DING Yihui
%A ZHAO Nan
%A
SHEN Xinyong
%A DING Yihui
%A ZHAO Nan
%J 大气科学进展
%D 2006
%I
%X By using the 3D dynamic equations for small- and meso-scale disturbances, an investigation is performed on the heterotropic instability (including symmetric instability and traversal-type instability) of a zonal line-like disturbance moving at any angle with respect to basic flow, arriving at the following results:(1) with linear shear available, the heterotropic instability of the disturbance will occur only when flow shearing happens in the direction of the line-like disturbance movement or in the direction perpendicular to the disturbance movement, with the heterotropic instability showing the instability of the internal inertial gravity wave; (2) in the presence of second-order non-linear shear, the disturbance of the heterotropic instability includes internal inertial gravity and vortex Rossby waves. For the zonal line-form disturbance under study, the vortex Rossby wave has its source in the second-order shear of meridional basic wind speed in the flow and propagates unidirectionally with respect to the meridional basic flow. As a mesoscale heterotropic instable disturbance, the vortex Rossby wave has its origin from the second shear of the flow in the direction perpendicular to the line-form disturbance and is independent of the condition in the direction parallel to the flow; (3) for general zonal line-like disturbances, if the second-order shear happens in the meridional wind speed, i.e., the second shear of the flow in the direction perpendicular to the line-form disturbance, then the heterotropic instability of the disturbance is likely to be the instability of a mixed Rossby-internal inertial gravity wave; (4) the symmetric instability is actually the instability of the internal inertial gravity wave. The second-order shear in the flow represents an instable factor for a symmetric-type disturbance; (5) the instability of a traversal-type disturbance is the instability of the internal inertial gravity wave when the basic flow is constant or only linearly sheared. With a second or nonlinear vertical shear of the basic flow taken into account, the instability of a traversal-type disturbance may be the instability of a mixed vortex Rossby - gravity wave.
%K line-form disturbance
%K symmetric instability
%K traversal-type instability
%K heterotropic instability
%K vortex Rossby wave
%K wave property
不稳定性
%K 大气长波
%K 罗斯比波
%K 涡旋
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=E62459D214FD64A3C8082E4ED1ABABED5711027BBBDDD35B&cid=28A2F569B2458C17&jid=5434AFBF6CB6E7E8D67733B541F211C7&aid=3579CABF47FE373C8B09C4009FF8C4C6&yid=37904DC365DD7266&vid=EA389574707BDED3&iid=0B39A22176CE99FB&sid=4133DDB79B497495&eid=211C7E02AC474301&journal_id=0256-1530&journal_name=大气科学进展&referenced_num=0&reference_num=19