Colloquium


DATE2020-10-08 15:10-16:00

PLACE數學館3174教室

SPEAKER郭鴻基 講座教授(台灣大學大氣科學系

TITLETwo-Dimensional Turbulence and Typhoon Vorticity Dynamics (兩度空間亂流與颱風渦度動力)

ABSTRACT Earth’s atmosphere and ocean, under the influence of rotation and density stratification, exhibit complex patterns of fluid motion over a wide range of space and time scales. The two-dimensional turbulence, which may be stemmed either from the fluid rotation or the fluid internal stratification, has been a paradigm for atmospheric oceanic fluid dynamics (AOFD). It is a remarkable fact that for any type of random initial state or external forcing, a two-dimensional fluid will rapidly organize itself into a system of coherent, interacting vortices swimming through a sea of passive filamentary structure produced from earlier vortex interactions. This discipline has also been instrumental in the development of single charge plasma physics, galaxy spiral, the Great Red spot, the ozone-hole problem and the typhoon dynamics. A brief review of 2D and 3D turbulence will be given. The mathematical nature of the 2D turbulence will be addressed. The nonlinear typhoon vorticity dynamics, such as merger dynamics, the eyewall rotation and mixing, the successive formation of tropical vortices and the concentric eyewall formation dynamics will be presented. These nonlinear vorticity dynamics are shown to bear great resemblance to the observations. 演講討論兩度空間亂流與颱風渦度動力。地球大氣海洋流體受地球旋轉與密度層化影響,其動力特性是兩度空間亂流學的典範;兩度空間亂流非線性尺度交互是往大尺度移動,渦漩合併成大渦漩以及大量環繞周邊細絲渦度帶,是兩度空間亂流特性。介紹以兩度空間亂流相關的物理現象,並以此觀點探討的颱風渦度動力,也會討論數學與此動力的相關性。