Correlation coefficients between the seasonally aggregated climate data and the four residual chronologies, the RES-chronology based PC#1 series, the corresponding first-order difference series of PC#1, and the 5-year smoothed series of PC#1 over their common periods (Meteorological data cover 1951

Tem = mean temperature; Tmax = maximum temperature; Tmin = minimum temperature; Pre = precipitation; PDSI = Palmer Drought Severity Index; RH = relative humidity; p means previous year; c means current year; HS means the higher-site; HMS means the higher-mid site; MS means mid-site; LS means lower-site. ** means correlation is significant at the p = 0.01 level, * means correlation is significant at the p = 0.05 level. The significance testing of the 5-year smoothed series was based on the adjusted degree of freedom method described by Bretherton et al. [51].