Characteristics and climatology of eyewall replacement cycles for Atlantic tropical cyclones from observations

Eyewall replacement cycles in major tropical cyclones (TCs) are quite frequent. As the secondary eyewall overtakes the primary eyewall, the structure of the tropical cyclone is greatly modified. After the replacement cycle, the TC usually emerges with lower wind speed and larger radius of maximum winds, thus possibly affecting greater areas than originally forecasted. When TCs with double eyewalls form close to offshore and onshore properties they can cause a lot of devastation and damage. We use vortex data messages and flight-level data from the Air Force reconnaissance flights and the NOAA research flights to determine all replacement cycles that have been observed for Atlantic historical storms. For this study, the secondary ring of convection needs to display a distinct wind maximum to be classified as a secondary eyewall. The number of hours required to complete an eyewall replacement cycle is highly variable from storm to storm and sometimes from cycle to cycle for the same storm, and we discuss the full range of possibilities. We also identify when and where eyewall replacement cycles are most likely to occur. Such climatology would help determine the main regions in the Atlantic basin that can be affected by such phenomena.