Atlantic Multidecadal Oscillation and Solar Forcing Modulate Decadal‐Scale Variability in Northwest Pacific Tropical Cyclone Precipitation

Abstract

Extreme precipitation associated with tropical cyclones (TCs) poses a growing threat to coastal communities, yet short instrumental records hamper the assessment of long‐term variability. Here, we address this gap by developing a quantitative proxy for TC precipitation using a previously published, monthly resolved coral oxygen isotope (δ ¹⁸ O) record. This record was derived from a single Porites coral specimen collected offshore southern Taiwan, a region within the most active TC zone of the Northwest Pacific. Because coral δ ¹⁸ O reflects both sea surface temperature and seawater δ ¹⁸ O, we infer TC precipitation from the hydrological and isotopic imprint of isotopically depleted freshwater input recorded by the coral. Calibrated against modern data (1998–2012 CE), the proxy identified extreme TC events with a detection rate of ∼78%. We reconstructed a coral‐based index of TC precipitation variability for 1906–2012 CE. We then characterized the low‐frequency variability of the reconstructed index using spectral analysis and evaluated its associations with major climate drivers using correlation analyses. The 106‐year record revealed pronounced interdecadal variability primarily modulated by the Atlantic Multidecadal Oscillation and solar forcing, while the influences of El Niño–Southern Oscillation and Pacific Decadal Oscillation were non‐stationary, becoming more coherent after the 1950s. Our reconstruction constrains pre‐instrumental TC hydroclimate variability and its drivers, informing future projections and coastal risk assessment under continued warming.