We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Island‐Induced Eyewall Replacement in a Landfalling Tropical Cyclone: A Model Study of Super Typhoon Mangkhut (2018).
- Authors
Lau, K. H.; Tam, C.‐Y.; Wu, C.‐C.
- Abstract
An unconventional, island‐induced eyewall replacement (IER) occurred in Super Typhoon Mangkhut (2018) when it crossed Luzon Island. Upon landfall, its original compact eyewall broke down and dissipated rapidly. As Mangkhut exited Luzon and entered the South China Sea, a much larger new eyewall formed at a radius of 150–200 km from the storm center, three times larger than the original one. Unlike the eyewall replacement cycle in intense tropical cyclones, the breakdown of the original eyewall preceded the formation of the new eyewall (NEF) in Mangkhut. This evolution was reproduced reasonably well in a control experiment using the Weather Research and Forecasting Model. Two sensitivity experiments showed that the IER was triggered by Luzon Island, whose terrain is essential for not only the destruction of the original eyewall but also the NEF. In an axisymmetric framework, it is demonstrated for the first time that the NEF was preceded by the following processes: (a) an increase in the outward‐directed agradient force in the boundary layer (BL) inflow region after landfall due to differential rates of weakening between the radial pressure gradient and the tangential wind, (b) creation of a BL deceleration zone, (c) localized reinforcement of BL inflow deceleration within the NEF region when Mangkhut re‐entered the ocean, following an exisiting framework of an unbalanced dynamical pathway, and (d) strengthening of the BL convergence and uplift which initiated and sustained the deep convection of the new eyewall. Plain Language Summary: The strongest wind and rain in a tropical cyclone (TC) usually occur in the eyewall, a ring of towering thunderstorms surrounding the eye. A powerful TC named Mangkhut had an unusual change in its eyewall when it crossed Luzon Island. Normally, the original eyewall of a TC would get replaced by a new eyewall that forms outside of it, but Mangkhut behaved differently. As it hit land, its original eyewall quickly broke down and disappeared. However, when Mangkhut re‐entered ocean, a new eyewall formed. This new eyewall was three times larger than the original one. Using a numerical model, this evolution was reasonably well simulated. We found that Luzon Island triggered the eyewall replacement, and its terrain was crucial for the process. It was also demonstrated that an imbalance of forces in the boundary layer, the lowest part of the atmosphere in contact with Earth's surface, decelerated inflowing air at the radius where the new eyewall formed. This deceleration was reinforced after the storm re‐entered ocean. The convergence and uplift caused by this deceleration ultimately formed the new eyewall. Understanding this unusual eyewall evolution helps us understand how TCs change as they traverse islands, thereby improving storm predictions and preparations. Key Points: Numerical experiments showed that Luzon Island triggered an unconventional eyewall replacement in Super Typhoon Mangkhut upon landfallUnbalanced boundary layer forcings after landfall decelerated the inflow over the region where the new eyewall subsequently formedReinforced deceleration of inflow after re‐entering the ocean induced strong convergence and uplift that culminated in new eyewall formation
- Subjects
LUZON (Philippines); TROPICAL cyclones; ATMOSPHERIC boundary layer; TYPHOONS; METEOROLOGICAL research; WEATHER forecasting; LANDFALL
- Publication
Journal of Geophysical Research. Atmospheres, 2024, Vol 129, Issue 4, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2023JD039541