Hydroclimate variability in the North China Plain and its link with El Niño–Southern Oscillation since 1784 A.D.: Insights from tree‐ring cellulose δ 18 O

We present here a chronology of tree‐ring cellulose δ 18 O from 1784 to 2003 that is based on the individual measurements of five Larix principis‐rupprechtii trees growing in the semiarid North China Plain (NCP; 34°–41°N, 107°–120°E). This chronology has a significant, negative correlation with summer precipitation, relative humidity, and the Palmer Drought Severity Index. It is representative of regional summer hydroclimate variability in the NCP by analyzing its spatial correlation patterns with CRU TS3 precipitation grid data sets. Historically, extreme climate events (drought and flood) could be detected by the high‐frequency (annual) signals in the chronology. The low‐frequency (11 year moving average) signals are consistent with the time series of the drought frequency and the regional dryness‐wetness index derived from historical documents in the NCP. Significant spatial correlation patterns of measured precipitation and the tree‐ring cellulose δ 18 O chronology from the NCP with observed sea surface temperature in the eastern equatorial Pacific during the 1954–2003 and 1854–2003 periods suggest that the summer hydroclimate of the NCP has a close link with El Niño–Southern Oscillation. Mostly extreme dry or wet years identified by the chronology follow historical El Niño or La Niña events over the past 220 years, respectively.