Abstract
Conventional urban-scale precipitation characterization often overlooks the uniqueness of typhoon rainfall specifically in intensity–duration–frequency (IDF) relationships and rainfall patterns. This study used meteorological station observations and assimilated gridded datasets from Ningbo, China, to derive county-level IDF curves and to extract typical spatiotemporal patterns using
K
-means clustering for typhoon rainfall. The main findings are as follows. The impacts of typhoon-related rainfall in Ningbo are dominated by long-duration extreme rainfall, most notably 24 h rainfall. Current published IDF curves underestimate the extremes for such events. Furthermore, comparison of the results for two periods (1980–2014 and 1980–2024) revealed spatially inhomogeneous enhancement of typhoon impacts, with notable increase in the northern region. The extracted temporal rainfall patterns were found dominated by the central-peaked pattern (with rainfall concentrated in the middle phase) and the late-peaked pattern, differing substantially from the Chicago hyetograph. The latter exhibits limitation in characterizing the structure of long-duration typhoon rainfall because it tends to overestimate peak rainfall intensity. Spatially, rainfall patterns were categorized into dispersed-dominated and concentrated types. The study also identified the key influencing factors through statistical analysis across typhoon rainfall patterns. These offers a scientific reference for urban resilience in typhoon-prone coastal regions with systemic vulnerability to extreme typhoon rainfall.