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

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Publicado en:Biogeosciences vol. 22, no. 1 (2025), p. 55
Autor principal: Nagavciuc, Viorica
Otros Autores: Helle, Gerhard, Rădoane, Maria, Cătălin-Constantin Roibu, Mihai-Gabriel Cotos, Ionita, Monica
Publicado:
Copernicus GmbH
Materias:
Danube River
Europe
Romania
Climate variability
Oxygen isotope ratio
Cellulose
Topography
Cloud cover
Isotope ratios
Precipitation
Drought
Wave number
Water
Pressure anomalies
Evapotranspiration
Trees
Ocean circulation patterns
Reconstruction
Climate change
Extreme values
Moisture
Relative humidity
Variability
Dendrochronology
Correlation
Dry periods
Oxygen
Software
Humidity
Regression models
Atmospheric circulation
Moisture availability
Atmospheric circulation patterns
Oxygen isotopes
Long-term changes
Isotopes
Evapotranspiration-precipitation relationships
Decadal variations
Teleconnection patterns
Sunshine duration
Tree rings
Environmental
Acceso en línea:Citation/Abstract
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Resumen:This study investigates the relationship between oxygen isotope ratios (<inline-formula>δ18</inline-formula>O) in oak tree ring cellulose and past drought variability in Letea Forest, Romania. A <inline-formula>δ18</inline-formula>O site chronology spanning 1803–2020 was compiled from seven individual time series. <inline-formula>δ18</inline-formula>O values exhibited a significant negative correlation with moisture-related variables (cloud cover, relative humidity, and precipitation) and a positive correlation with temperature and sunshine duration. This confirms that <inline-formula>δ18</inline-formula>O from tree rings can be a good proxy for moisture availability. The strongest correlation was found between <inline-formula>δ18</inline-formula>O and the August Standardized Precipitation Evapotranspiration Index for an accumulation period of 9&#xa0;months (SPEI9) for central and eastern Europe. This highlights SPEI9 as a superior indicator of drought compared to individual parameters like temperature or precipitation. Using a linear regression model, we reconstructed August SPEI9 variability for the past 200&#xa0;years. The reconstruction captured interannual and decadal variations, with distinct wet and dry periods. Analysis of large-scale atmospheric circulation patterns revealed a link between high <inline-formula>δ18</inline-formula>O values (indicating dry conditions) and a high-pressure system over the North Atlantic. Conversely, low <inline-formula>δ18</inline-formula>O values (indicating wet conditions) corresponded to negative pressure anomalies over Europe. Moreover, extreme values of <inline-formula>δ18</inline-formula>O are also associated with the prevalence of a hemispheric teleconnection pattern, namely wave number 4. This <inline-formula>δ18</inline-formula>O chronology and the corresponding August SPEI9 reconstruction offer valuable tools for understanding past climate variability and its relationship with large-scale atmospheric and oceanic circulation patterns.
ISSN:1726-4170
1726-4189
DOI:10.5194/bg-22-55-2025
Fuente:Engineering Database