Seasonal and Latitudinal Variations of Tropical Cyclones in Chinese Historical Documents

Paleoclimate records are valuable for exploring pre-industrial climate variability and change and for evaluating climate simulations. Most paleoclimate records are point-based proxies and coarsely resolve event timing, so they often lack the spatial coverage or the temporal resolution to resolve broad spatial-temporal changes in extremes such as tropical cyclones (TC). Here we investigate the long-term variability of TC activity in East Asia using Chinese historical records from 1368 to 1912. The TC records crowd-sourced by ancient intellectuals show a climatology that resembles modern observations. Analysis reveals an apparent shift in the seasonal cycle of about 30 days (delayed) and a 5-degree southward shift in TC occurrence over the five centuries of the proxy record. Comparing the early-1800s paleo records with modern (1971-2020) observations suggests a potential earlier seasonal occurrence and northward shift in TC activity in the modern period than in the early 1800s. Further analysis highlights a correlation between past TC activity as inferred from historical documents and both tropical ocean temperature and extratropical land temperature. Since these environmental factors will also be modulated by greenhouse warming and aerosol-induced changes, the relationships shown by comparing TC metrics in historical documents and paleoclimate reanalyses may provide clues—independent from climate models—for how greenhouse gases and aerosols may modulate future TC activity in China-East Asia region. This study provides a unique and complementary exploration of the long-term variability of TC activity in China-East Asia and may help inform future research and mitigation strategies.