Spatial Patterns of Precipitation Anomalies for 30-yr Warm Periods in China During the Past 2000 Years

The spatial patterns of precipitation anomalies during five 30-yr warm periods of 691–720, 1231–1260, 1741–1770, 1921–1950, and 1981–2000 were investigated using a dryness/wetness grading dataset covering 48 stations from Chinese historical documents and 22 precipitation proxy series from natural archives. It was found that the North China Plain (approximately 35°–40°N, east of 105°E) was dry in four warm periods within the centennial warm epochs of 600–750, the Medieval Warm Period (about 900–1300) and after 1900. A wet condition prevailed over most of China during 1741–1770, a 30-yr warm peak that occurred during the Little Ice Age (about 1650–1850). The spatial pattern of the precipitation anomaly in 1981–2000 over East China (25°–40°N, east of 105°E) is roughly consistent with that in 1231–1260, but a difference in the precipitation anomaly appeared over the Tibetan Plateau. The spatial patterns of the precipitation anomalies over China varied between all five 30-yr warm periods, which implies that the matching pattern between temperature and precipitation change is multiform, and the precipitation anomaly could be positive or negative when a decadal warm climate occurs in different climate epochs. This result may provide a primary reference for the mechanism detection and climate simulation of the precipitation anomaly of the future warm climate.