River freeze-up date anomalies during the sixteenth to nineteenth centuries in southern Northeast China reconstructed from the Korean Envoys Yanxing Book

This study reconstructed the river freeze-up date anomalies utilizing historical river ice records from the Korean Envoys Yanxing Book (韩使燕行录) for the 60 years spanning the sixteenth to nineteenth centuries in southern Northeast China. The main changing features of river freeze-up phenology are summarized as follows: (1) The river freeze-up date was 5 days earlier than the modern mean during the sixteenth to nineteenth centuries in southern Northeast China; (2) during the study period, four colder and earlier freeze-up periods are identified of 1533–1572, 1619–1690, 1712–1729, and 1822–1888, as well as two warmer and delayed freeze-up periods of 1610–1617 and 1755–1803; (3) this study gave more detailed reconstructions on the river freeze-up phenology and temperature change than the previous studies, specifically the warmer in 1610–1617 indicated by the delayed freeze-up dates, the colder period in the 1720s indicated by the earlier freeze-up dates, and the warm period during the mid-to-late eighteenth century lasting until the 1790s at least.