A Top-Down Pathway to Secondary Eyewall Formation in Simulated Tropical Cyclones

Bryce Tyner, Ping Zhu, Jun A. Zhang, Sundararaman Gopalakrishnan, Frank Marks, Vijay Tallapragada

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Idealized and real-case simulations conducted using the Hurricane Weather Research and Forecasting (HWRF) model demonstrate a “top-down” pathway to secondary eyewall formation (SEF) for tropical cyclones (TCs). For the real-case simulations of Hurricane Rita (2005) and Hurricane Edouard (2014), a comparison to observations reveals the timing and overall characteristics of the simulated SEF appear realistic. An important control of the top-down pathway to SEF is the amount and radial-height distribution of hydrometeors at outer radii. Examination into the simulated hydrometeor particle fall speed distribution reveals that the HWRF operational microphysics scheme is not producing the lightest hydrometeors, which are likely present in observed TCs and are most conducive to being advected from the primary eyewall to the outer rainband region of the TC. Triggering of SEF begins with the fallout of hydrometeors at the outer radii from the TC primary eyewall, where penetrative downdrafts resulting from evaporative cooling of precipitation promote the development of local convection. As the convection-induced radial convergence that is initially located in the midtroposphere extends downward into the boundary layer, it results in the eruption of high entropy air out of the boundary layer. This leads to the rapid development of rainband convection and subsequent SEF via a positive feedback among precipitation, convection, and boundary layer processes.

Original languageEnglish (US)
Pages (from-to)174-197
Number of pages24
JournalJournal of Geophysical Research: Atmospheres
Issue number1
StatePublished - Jan 16 2018


  • eyewall replacement cycle
  • HWRF
  • secondary eyewall formation
  • tropical cyclone

ASJC Scopus subject areas

  • Atmospheric Science
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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