The development of potential vorticity in a hurricane-like vortex

✍ Scribed by J. D. Möller; R. K. Smith

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 636 KB
• Volume: 120
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49712051907

✦ Synopsis

Abstract

We investigate the time evolution of the potential‐vorticity distribution in an axisymmetric hurricane‐like vortex using a numerical model based on a formulation by Schubert and Alworth. In particular, we compare the vortex response to an annular heating function with that in the analytic calculation by Schubert and Alworth in which the maximum heating rate occurs on the vortex axis. The annular heating function is intended to better represent the latent‐heat release in the eye‐wall clouds of a hurricane. We show that after about four days of integration time in the Schubert—Alworth calculation, the isentropes near the vortex centre, and hence the prescribed heating function, become concentrated near the surface in physical space. In comparison, for the annular heating distribution the descent of the isentropes is less marked and the vertical distribution of the heating in physical space remains more realistic vis‐à‐vis a hurricane. It is significant that in this case the potential‐vorticity maximum lies not on the vortex axis, as in the Schubert—Alworth calculation, but close to the radius of maximum heating. This appears to be consistent with observations in hurricanes. Finally we show that, counter to intuition, there is greater subsidence on the vortex axis in the case where the heating is a maximum on the axis. A dynamical explanation is offered for this result.