Relative humidity variation derived from tree‐ring δ¹⁸O and possible large‐scale atmospheric circulations linkage over the Guanzhong Plain, central northern China, since 1760 CE

Abstract

China is drastically influenced by the Asian monsoon. Based on the relationship (r = −.636, N = 62, p < .001) between tree‐ring δ18O values from nine cores of Pinus tabulaeformis Carr. from Nanwutai and the Asia monsoon‐related June–August relative humidity (RHJJA), we designed a transfer function reconstructing the RHJJA variation from 1760 to 2018 CE. Our RHJJA reconstruction captured some extreme climatic events that occurred in the past, such as the Ding‐Wu disaster (1876–1878 CE), which was the most serious drought event of northern China in the 19th century, and the severe drought event of 1925–1930 CE. The spatial correlation analysis shows that our RHJJA reconstruction has not only local but also large‐scale hydroclimate circulations. Our reconstruction compared well with other hydroclimate series from northern China, indicating the large‐scale representativeness of our reconstruction. Both the ensemble empirical mode decomposition (EEMD) and the periodicity analyses revealed that the El Niño–South Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the Arctic Oscillation (AO) and the solar activity strongly affected Asian monsoon‐related RHJJA changes over Guanzhong Plain in the past. We believe this study is of great significance and provides an in‐depth understanding of climate change in the Guanzhong Plain and in northern China.

Carbon stress causes preferential storage over growth in treeline trees

“…The Qinling Mountains are an obvious geographical demarcation line between northern and southern China and the most critical boundary for vegetation distribution between the warm-temperate and subtropical zones in eastern mainland China (Liu et al, 2009). The northern slope of the Qinling Mountains is characterized by a warm-temperate climate with relatively dry summers and cold winters (Liu et al, 2021). Mean annual temperatures in this region range from 1 to 6 C above 2000 m and from 6 to 11 C below 2000 m a.s.l, with a lapse rate of 0.50 ± 0.02 C/100 m (Tang and Fang, 2006).…”