期刊
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
卷 14, 期 10, 页码 4488-4503出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/ggge.20256
关键词
oxygen isotopes; tree cellulose; California; El Nino
资金
- National Science Foundation [AGS-1049238]
- NOAA/CPO Climate Change & Detection Program: Paleoclimate Studies [NA10OAR4310129]
- Div Atmospheric & Geospace Sciences
- Directorate For Geosciences [1049238] Funding Source: National Science Foundation
The oxygen isotope ratio (delta O-18) of precipitation in continental, midlatitude regions is a complex measure of atmospheric dynamics and regional climate variability and can be preserved in geologic archives. However, continuous modern observations of precipitation delta O-18 in many midlatitude regions, particularly in the coastal western United States, are sparse. Here, tree-ring cellulose delta O-18 from southern California is used to assess the potential of this proxy as an indicator of long-term hydroclimate and atmospheric variability. From 1954 to 2004, we observed that cellulose delta O-18 was well replicated within a single stand of blue oak (Quercus douglasii) on interannual and decadal time scales. By using a forward mechanistic model, we demonstrate that cellulose delta O-18 is not driven solely by the oxygen isotope composition of precipitation at the site nor any other single hydroclimate variable. Instead, the interannual variability in cellulose delta O-18 prior to 1979 is positively correlated with growing season soil water delta O-18 and after 1979 is negatively correlated with relative humidity. In addition, 2 years (1983 and 1998) of anomalously low cellulose delta O-18 coincided with the wettest years in California and the strongest El Nino events of the late 20th century. For these years, decreased near surface evaporation and/or increased upper-level condensation could account for the more depleted cellulose delta O-18 values. While blue oak cellulose delta O-18 is sensitive to atmospheric and hydroclimate variability, the varying temporal correlation between the cellulose delta O-18 and different environmental variables complicates any attempt to use the cellulose oxygen isotopes for reconstructions of climate variability beyond the calibration period.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据