Drought reconstruction for North Central China from tree rings: the value of the Palmer drought severity index



We present a drought reconstruction for north central China based on a tree ring-width chronology developed from two sites of the Chinese pine (Pinus tabulaeformis) in the northern Helan Mountains. The drought reconstruction, spanning 1788–1999 A.D., was developed by calibrating tree-ring data with the Palmer drought severity index (PDSI), an index that describes the regional moisture condition properly. The reconstruction was verified with independent data, and accounts for 45.7% of the actual PDSI variance during their common period (1941–1999). The full reconstruction indicates that the regional drought variability was relatively stable during the nineteenth century, but became more variable and persistent during the twentieth century. The drought epoch in the late 1920s was the most severe one in our reconstruction. In contrast to a wetting trend in the western area of northwest China, a clear drying trend has occurred in north central China since mid-1930s. The multitaper method (MTM) spectral analysis indicates the existence of some decadal (∼11.4 year) and interannual (9.1, 6.8, 4.0, 2.7 and 2.1–2.0 year) cycles, which may potentially be the fingerprints of some proposed climate change forcings. Copyright © 2006 Royal Meteorological Society