Scientific Reports (Jun 2017)

Near-surface coherent structures explored by large eddy simulation of entire tropical cyclones

  • Junshi Ito,
  • Tsutao Oizumi,
  • Hiroshi Niino

DOI
https://doi.org/10.1038/s41598-017-03848-w
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 10

Abstract

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Abstract Taking advantage of the huge computational power of a massive parallel supercomputer (K-supercomputer), this study conducts large eddy simulations of entire tropical cyclones by employing a numerical weather prediction model, and explores near-surface coherent structures. The maximum of the near-surface wind changes little from that simulated based on coarse-resolution runs. Three kinds of coherent structures appeared inside the boundary layer. The first is a Type-A roll, which is caused by an inflection-point instability of the radial flow and prevails outside the radius of maximum wind. The second is a Type-B roll that also appears to be caused by an inflection-point instability but of both radial and tangential winds. Its roll axis is almost orthogonal to the Type-A roll. The third is a Type-C roll, which occurs inside the radius of maximum wind and only near the surface. It transports horizontal momentum in an up-gradient sense and causes the largest gusts.