Hydroclimate variability in the North China Plain and its link with El Nino-Southern Oscillation since 1784 AD: Insights from tree-ring cellulose delta(18)O

We present here a chronology of tree-ring cellulose delta(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 degrees-41 degrees N, 107 degrees-120 degrees 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are consistent with the time series of the drought frequency and the regional dryness-wetness index derived from historical documents in the NCP.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 delta(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 Nino-Southern Oscillation. Mostly extreme dry or wet years identified by the chronology follow historical El Nino or La Nina events over the past 220 years, respectively.</p

Tree-ring-based annual precipitation reconstruction in Kalaqin, Inner Mongolia for the last 238 years

A tree-ring-width chronology of Pinus tabulaeformis from Kalaqin, Inner Mongolia was developed using modern dendrochronological techniques. Based on the results of correlation function analysis, the total precipitation from the previous August to current July was reconstructed for 1771-2008 AD with an explained variance of 49.3%. The reconstruction correlated well with the dryness/wetness series derived from historical documents, as well as the precipitation reconstruction of the Chifeng-Weichang region. There were eight intervals with greater precipitation than the average (associated with the strong East Asian summer monsoon) and seven intervals lower than the average (weak monsoon). A power spectrum analysis showed that there were 120 a, 80 a, 8 a and 2 a periodicities.</p