Tree ring-based winter temperature reconstruction for Changting, Fujian, subtropical region of Southeast China, since 1850: linkages to the Pacific Ocean

Until recently, there have been very few tree-ring studies in southeast China due largely to the scarcity of old trees and the complexity of relationships between tree growth and climate in subtropical regions of China. Recent studies on the conifers in southeast China revealed that tree ring-based climate reconstructions are feasible. Here, we describe a reconstruction (AD 1850-2009) of November-February maximum temperatures for Changting, Fujian, southeast China based on tree ring width data of Pinus massiniana which considerably extends the available climatic information. Calibration and verification statistics for the period 1956-2009 show a high level of skill and account for a significant portion of the observed variance (32.9%) irrespective of which period is used to develop or verify the regression model. Split sample validation supports our use of a reconstruction model based on the full period of reliable observational data (1956-2009). Warm periods occurred during 1854-1859, 1868-1880, 1885-1899, 1906-1914, 1920-1943, 1964-1975 and 1994-present; while the periods of AD 1850-1853, 1860-1867, 1881-1884, 1900-1907, 1915-1919, 1944-1963 and 1976-1993 were relatively cold. The climate correlation analyses with gridded temperature dataset and SST revealed that our season temperature reconstruction contains the strong large-scale climate signals. Our results suggest that some warm winters of Changting are coincident with El Nio events over the past 150 years. In addition, several severely cold winters coincide with major volcanic eruptions.