Tree-ring reconstruction of January-March minimum temperatures since 1804 on Hasi Mountain, northwestern China

A new chronology was developed using Pinus tabulaeformis tree-ring data obtained from Hasi Mountain in northwestern China. On the basis of a correlation analysis between the tree-ring width and climate data, a January-March minimum temperature series from 1804 to 2009 was reconstructed. The tree-ring chronology explains 37.1% of the instrumental temperature variance during the period of 1958-2007. The temperature reconstruction showed warm intervals occurred in 1812-1826, 1831-1848, 1877-1885, 1898-1918, 1923-1936, and 1988-2007, while cold periods occurred in 1804-1811, 1886-1897, and 1941-1981. The warm and cold periods correspond to droughts and wet periods, respectively. A warming trend since the 1950s has been observed, which coincides with results from other reconstructions based on tree-ring data from the neighboring area. A spatial correlation indicates that the reconstructed temperature has a significant teleconnection with sea surface temperatures (SSTs) in the northern and eastern tropical Pacific and Indian Oceans. The results from power spectrum and correlation analysis suggest that the El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and Arctic Oscillation (AO) can influence the winter temperature variation in northwestern China by controlling the strength of the East Asian Winter Monsoon (EAWM).