Pattern Formation from Two-dimensional Decaying Turbulence on a Rotating Sphere

Keiichi Ishioka, Michio Yamada (Graduate School of Mathematical Sciences, University of Tokyo), Yoshi-Yuki Hayashi (Department of Sciences, Hokkaido University), and Shigeo Yoden (Department of Geophysics, Kyoto University)


Time-evolutions of decaying turbulence in two-dimensional non-divergent fluid on a rotating sphere were conducted with high-resolution numerical model to examine what stream pattern appears finally.

To investigate the condition needed for each pattern to appear in detail, higher-resolution model are used and wider parameter range of initial condition or angular velocity of sphere rotation are swept than other past researches on the same subject.

As a result, it is confirmed that the appearance of easterly polar vortex when the angular velocity of sphere rotation is rapid is a robust feature. Furthermore, it turned out to be necessary for band structure of zonal flow to appear in middle and low latitudes that initial energy must be injected into small scale enough as well as the angular velocity of sphere rotation is rapid.

  1. Introduction
  2. Model and Method of Numerical Calculation
  3. Results
  4. Discussions and Conclusions
Received 30 September 1999; accepted 4 November 1999

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