Tropical cyclones near landfall can induce their own intensification through feedbacks on radiative forcing

Abstract

Rapid intensification of near-landfall tropical cyclones is very difficult to predict, and yet has far-reaching consequences due to their disastrous impact to the coastal areas. The focus for improving predictions of rapid intensification has so far been on environmental conditions. Here we use the Coupled-Ocean-Atmosphere-Wave-Sediment Transport Modeling System to simulate tropical cyclones making landfall in South China: Nida (2016), Hato (2107) and Mangkhut (2018). Two smaller storms (Hato and Nida) undergo intensification, which is induced by the storms themselves through their extensive subsidence ahead of the storms, leading to clear skies and strong solar heating of the near-shore sea water over a shallow continental shelf. This heating provides latent heat to the storms, and subsequently intensification occurs. In contrast, such heating does not occur in the larger storm (Mangkhut) due to its widespread cloud cover. This results imply that to improve the prediction of tropical cyclone intensity changes prior to landfall, it is necessary to correctly simulate the short-term evolution of near-shore ocean conditions.

Coastal Downwelling Intensifies Landfalling Hurricanes

“…Future work will also examine boundary‐layer recovery mechanisms within the TC core, potentially using idealized studies. Finally, a recent study suggests insolation differences related to cloud‐cover may be important for TC intensification near landfall (Lok et al., 2021): we will extend the energy budget discussed here (Equation S1 in Supporting Information ) to consider radiative fluxes in addition to terms for potential‐ and internal‐energy advection.…”

The intensification of consecutive three tropical cyclones passing over a warm ocean eddy in the South China Sea

“…TC2 passed over the eddy on 20-21 July when WE1 and WE2 just merged as WE3 and intensified 20 kt during the 21 h (Figures 1B, 2B). Both TC1 and TC2 reached maximum intensity over the SCS when they closed to land, the intensification may result from shallow coastal warm water (Pun et al, 2019), coastal downwelling (Gramer et al, 2022), or positive feedback of radiative forcing (Lok et al, 2021). A tropical depression formed in the SCS on 21 August and moved westward, then passed through WE3 on 22 August when the eddy entered the decay phase.…”

Coastal downwelling intensifies landfalling hurricanes

“…Future work will also examine boundary-layer recovery mechanisms within the TC core, potentially using idealized studies. Finally, a recent study suggests insolation differences related to cloud-cover may be important for TC intensification near landfall (Lok et al, 2021): we will extend the energy budget discussed here (Equation S1 in Supporting Information S1) to consider radiative fluxes in addition to terms for potential-and internal-energy advection.…”