Solar activity, global surface air temperature anomaly and Pacific Decadal Oscillation signals observed in urban outskirts tree ring records from Shenyang, China

A tree ring width chronology constructed from multiple samples taken from Chinese pine trees growing in outskirts of Shenyang city in Liaoning Province (China) was studied for the first time in relation to solar activity, global surface air temperature anomalies and the Pacific Decadal Oscillation. The work revealed an excellent response of urban tree growth to solar activity and global climate change, show as the time variation of the main periodicities in the Sun–Earth indices and its corresponding variation as recorded in tree rings, indicating that these urban Chinese pine are a suitable proxy for Sun–Earth system research in heavy industrial region, like Fuling Mausoleum that is located in Shenyang. Chinese pines show significant synchronous response to solar activity, in the periodic band 5–8 years, 10–16 years and 20–30 years. At the same time, the wave signal of tree growth was also affected, or even amplified by the combined effect of the PDO and GSATA with a short lag time, revealing 6, 13.2, 16.6 and 23.2 years oscillatory modes. At 20–30 years timescales, Chinese pines validated the strongest PDO and GSATA influence signal at 26 years and 20.8 years, respectively, and the 20.8 years fluctuation of GSATA may be the first cause of the tree ring 23.5 years periodic waves. Urban tree ring growth is also more sensitive to low periodicity, especially in the 2–5 years band width.