Reconstructing Hydroclimatic Variability (1657 AD) Using Tree-Ring Time Series and Observed and Gridded Precipitation Data in Central Greece

This study evaluated the long-term hydroclimatic trend through a reconstruction procedure of precipitation variability in central Greece (1657–2020), using eight tree-ring chronologies (Pinus sp. and Abies sp.). Through the combination of gridded climate datasets with tree-ring width (TRW) and earlywood width (EWW) chronologies, we created three precipitation reconstructions, (1) April–August (AMJJA) and (2) May–June (MJ) using TRW and (3) EWW chronologies, utilizing both measured and gridded precipitation data. Chronologies were standardized using ARSTAN, while principal component analysis (PCA) was used for the development of the reconstructions. Verification and calibration of the derived time series (split-period tests, RE > 0, R = 0.62–0.67) confirmed a strong reconstruction that explained 15%–45% of the variability in precipitation. The results revealed strong growth–precipitation relationships throughout spring–summer (AMJJA/MJ). Multi-decadal variability is captured by TRW chronologies, while higher-frequency signals are reflected by EWW. Significant time intervals (19.6-, 12.5-, and 2.2-year cycles) were found by spectral analysis, indicating climatic impacts on tree-ring chronologies. Extremely wet (e.g., 1885, 1913) and dry (e.g., 1894–1895) episodes were confirmed against regional paleoclimate data and were consistent among previous reconstructions (72%–92% agreement). Despite the fact that sample depth reduced after 1978, the EPS was constantly higher than the threshold (EPS > 0.85 post-1746), showing the reliability of the reconstruction. This study expanded the hydroclimatic record of the southeast Mediterranean and highlighted that tree-ring chronologies are reliable variables to predict the historical precipitation.