A long-term drought reconstruction (August SPEI9) based on oxygen isotope tree ring data for central and eastern parts of Europe (Romania)

Description of Reconstructed August SPEI9 Data Set

This data set represents a reconstruction of the August Standardized Precipitation Evapotranspiration Index (SPEI9) variability for the past 200 years (1807-2020) in central and eastern Europe. The reconstruction was achieved through a novel approach utilizing tree-ring δ18O records from oak trees (Quercus robur) sampled in the Letea Forest, Danube Delta, Romania.

Methodology:

A high-resolution δ18O chronology was developed from seven individual oak tree-ring δ18O time series.

A robust statistical model was established linking the δ18O values to instrumental SPEI9 data, demonstrating a strong correlation between August SPEI9 and δ18O. This indicates a high sensitivity of tree-ring δ18O to hydroclimatic conditions, particularly on longer timescales.

A linear regression model was then employed to reconstruct past August SPEI9 variability based on the δ18O chronology.

Data Characteristics:

Temporal Coverage: 1807-2020 

Spatial Coverage: Primarily applicable to central and eastern Europe.

Resolution: Annual

Variables: Reconstructed August SPEI9 values.

Key Features:

Captures both interannual and decadal variations in drought conditions.

Identifies distinct wet and dry periods throughout the past 200 years.

Provides valuable insights into past hydroclimatic variability, including periods of severe droughts that likely impacted the upstream Danube River catchment.

Notable Periods:

Wettest Periods: 1905-1915, 1934-1944, 1951-1958, 1980-1995

Driest Periods: 1818-1835, 1845-1854, 1882-1890, 2007-2020

Note: This description provides a concise summary of the key aspects of the reconstructed SPEI9 data set. For more detailed information, refer to the original research publication.