Cheugugi-Seoul daily precipitation dataset version 2 (1777–1907), analysis code, and SST-forced attribution experiments

Reconciled daily precipitation for Seoul, Korea, 1777-1907, from the Cheugugi (measuring rain gauge, standardized in 1441). Version 2 reconciles the original gauge restoration of Jhun and Moon (1997) with the independent documentary reconstruction of Lee et al. (2024), adjudicating every substantive discrepancy against the original Seungjeongwon Ilgi / Ilseongnok chronicle entries in the online database of the National Institute of Korean History (NIKH), which is adopted as the amount reference. Each day carries a per-day provenance label and an uncertainty flag; the record additionally preserves within-day timing (onset/end hour, continuation past midnight), the two separate chronicle readings, and a day-boundary-independent 24-hour maximum. Provided in CF-1.8 NetCDF and CSV, with the raw digitization and the analysis code used in the accompanying manuscript. Snow is not recorded by the gauge (liquid precipitation only); use the warm season for dryness analysis. The first recorded year (1777) is incompletely observed (the monsoon-peak month of July is blank) and should be excluded from climatological statistics; analyses in the accompanying paper begin in 1778. See README.md for the full column dictionary, provenance classification, and reproduction notes. The deposit also includes the SST-forced ("pacemaker") attribution experiments of the accompanying manuscript: the basin-masked monthly SST boundary forcing (tropical Pacific, North Atlantic, Indian Ocean, and global ocean), the Korea-box forced 850-hPa circulation response by basin, and a moisture-budget and basin-linearity diagnosis — the vertically integrated moisture-flux convergence (confirming a significant reduction in the moisture supply to Korea under the full forcing) and the additivity of the single-basin responses versus the global forcing — together with the analysis code. The attribution finds the low-level monsoon-circulation weakening over Korea to be driven principally by the Indian Ocean and North Atlantic, not the tropical Pacific despite its El Nino-like state. Method transparency: data reconciliation, chronicle parsing, and analysis were carried out with AI assistance (Claude, Anthropic) under the author's direction; the author verified the results and takes full responsibility.