摘要
对垂直切变基本流中刚盖海洋的大、中尺度波动作了波谱分析。发现随着基本流切变的增大和扰动波长的减小,涡旋波和重力惯性波的连续谱区会互相靠拢,最后发生重叠,这时已不能区分为快波、慢波;而能否重叠的关键在于临界波长与扰动波长的相对大小;基本流切变越大,扰动波长越短,重叠现象就越严重。这可用作尺度划分的客观标准。当波动尺度大于临界波长时,属大尺度,这时涡旋波和重力惯性波连续谱区互相不重叠,涡旋波是准地转的;当波动尺度小于临界波长而大于临界波长一半时,出现了涡旋波与重力惯性波连续谱区重叠的现象,并出现了涡旋-重力惯性混合波,而涡旋波是非地转的,此时运动属α中尺度。当波动尺度小于临界波长一半时,则已无纯粹的涡旋波,只有涡旋-重力惯性混合波和纯粹的重力惯性波,此时所有的运动均是非平衡的,该运动属β中尺度。采用这一方法划分的尺度标准与通常的标准在量级上相一致。
The wave spectral analysis is studied based on the rigid-lid ocean with the shear of basic flow. It is found that the continuous spectrum region of a branch of vortex wave can close to the region of a couple of internal inertial-gravitational wave, and they shall overlap each other finally, when the shear increases and the wavelength decreases. Under this condition fast wave can not be distinguished from slow wave. The overlapping condition is determined by the scale of critical wavelength and perturbation wave length. The stronger the vertical shear of the basic flow is, the shorter the perturbation wave length is, and the stronger the overlapping is. It can be used as a standard of the scales. When scale of wave is greater than the critical wavelength, the motion belongs to large scale. The continuous spectrum region doesn＇t overlap between the vortex wave and the internal inertial-gravitational wave, and the vortex wave is quasi-geostrophic. When scale of wave is less than the critical wavelength and greater than a half of the critical wavelength, the motion belongs to α-meso scale. And overlapping of the continuous spectrum region of vortex wave and inertial-gravitational wave occurs, which is the mixed wave. The vortex wave is not geotrophic. When scale of motion is less than a half of the critical wavelength, it belongs to β-meso scale, all motions are non-geostrophic balance. There are no pure vortex wave, but pure inertial-gravitational wave and mixed vortex-inertial gravitational wave. The standard is identical with the accustomed standard in magnitude.
出处
《海洋通报》
CAS
CSCD
北大核心
2008年第1期22-28,共7页
Marine Science Bulletin
基金
国家自然科学基金项目(40175014和40575023)
关键词
海洋波动
波谱分析
尺度划分
垂直切变基本流
连续谱
the wave in the ocean
the spectrum analysis
partition of the scale
the vertical shear of basic flow
continuous spectrum
