A long-term drought reconstruction based on oxygen isotope tree ring data for central and eastern parts of Europe (Romania)
<p>This study investigates the relationship between oxygen isotope ratios (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O) in oak tree ring cellulose and past drought variability in Letea Forest, Romania. A <span class="inline-f...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-01-01
|
| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/22/55/2025/bg-22-55-2025.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | <p>This study investigates the relationship between oxygen isotope ratios (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O) in oak tree ring cellulose and past drought variability in Letea Forest, Romania. A <span class="inline-formula"><i>δ</i><sup>18</sup></span>O site chronology spanning 1803–2020 was compiled from seven individual time series. <span class="inline-formula"><i>δ</i><sup>18</sup></span>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 <span class="inline-formula"><i>δ</i><sup>18</sup></span>O from tree rings can be a good proxy for moisture availability. The strongest correlation was found between <span class="inline-formula"><i>δ</i><sup>18</sup></span>O and the August Standardized Precipitation Evapotranspiration Index for an accumulation period of 9 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 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 <span class="inline-formula"><i>δ</i><sup>18</sup></span>O values (indicating dry conditions) and a high-pressure system over the North Atlantic. Conversely, low <span class="inline-formula"><i>δ</i><sup>18</sup></span>O values (indicating wet conditions) corresponded to negative pressure anomalies over Europe. Moreover, extreme values of <span class="inline-formula"><i>δ</i><sup>18</sup></span>O are also associated with the prevalence of a hemispheric teleconnection pattern, namely wave number 4. This <span class="inline-formula"><i>δ</i><sup>18</sup></span>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.</p> |
|---|---|
| ISSN: | 1726-4170 1726-4189 |