East Asian summer precipitation (EASP) alternates interannually mainly between a meridional tripole mode (with a wet Yangtze River basin and dry north/south) and a dipole mode (with a wet south and dry north). How associated moisture pathways reorganize remains poorly quantified from a Lagrangian perspective. We analyze moisture transport to East Asia during July–August 1961–2022 using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to trace backward air-parcel trajectories, categorizing pathways into four quadrants (SW, SE, NW, NE). Climatologically, the SW pathway dominates, supplying 48% of the total moisture. The positive tripole mode, driven by a southwestward-shifted western Pacific subtropical high (WPSH), reduces SE moisture by 25% while the other three paths strengthen. In the positive dipole mode, an eastward-retreating WPSH and prevalent northerlies boost NE moisture by 42% but reduce SE and NW by 14% and 7%. This pathway-resolved budget links circulation regimes to rainfall anomalies, advances understanding of EASP variability, and also provides an analogue for interpreting moisture‑sensitive paleoclimate records.

Precipitation variation,Moisture transport,Lagrangian analysis,East Asian summer precipitation