Impacts of initial structure of tropical cyclone on secondary eyewall formation

The secondary eyewall replacement cycle (ERC) is an important aspect for tropical cyclone (TC) intensity and structure forecasts. Both observational studies and idealized simulations are conducted to explore the sensitivity of secondary eyewall formation (SEF) to the initial structure of the tropical cyclone. It is found that a TC with a larger size (i.e. both the radial of maximum wind and outer size) is apt to SEF. Furthermore, a larger TC likely has a potential to form a larger outer eyewall and thus a wider moat region. The different SE structures may lead to different intensity fluctuations. This study motivates further research with respect to how initial structure influences the storm intensity and structure changes.