Impact of warming on rainfall changes in damaging Philippine typhoons using high-resolution convection-permitting models

Abstract

This study has investigated the changes in tropical cyclone (TC)-associated precipitation in the Philippines under past (pre-industrial) and future climate scenarios using the pseudo-global warming (PGW) technique and dynamical downscaling. The novelty of this work is in the use of high-resolution PGW simulations (3 and 5 km) and a multiple-experimental approach to directly quantify TC precipitation changes over the Philippines, as well as the decomposition of TC rainfall changes in thermodynamic and dynamic contributions. Future climate simulations project a significant increase in TC precipitation, consistent with Clausius-Clapeyron (CC) scaling expectations. However, small deviations from this expected scaling are noted, attributed to factors such as increased TC intensity and atmospheric warming. The simulated TC precipitation in the past climate is found to be lower than that in the current climate, with inner-core precipitation increases of ∼ 6 %–8 % from past to present conditions. Under future warming (SSP5-8.5), simulations indicate robust increases in TC rainfall rates for intense TCs such as Haiyan (2013), Bopha (2012), and Mangkhut (2018), with strongest amplification in the inner-core region. Extreme rainfall increases disproportionately (locally exceeding 30 %–40%), indicating a shift toward short-duration, high-intensity rainfall events rather than uniform rainfall enhancement. However, our results show that this increase is primarily driven by thermodynamic effects (≈ 20 %–30 %), while dynamical contributions are smaller (≈ -10 % to -30 %) and often partially offset the total rainfall response. Overall, the results demonstrate that TC rainfall scaling in a warming climate is primarily moisture-driven, with TC case-to-case dynamics modulating the TC associated rainfall response. Our study underscores that variations in TC intensity and structure play a crucial role in influencing the scaling relationship between sea surface temperatures and TC-associated precipitation in the Philippines.