Climatologic and hydrologic influences on the oxygen isotope ratio of tree cellulose in coastal southern California during the late 20th century

摘要: [1] The oxygen isotope ratio (δ18O) of precipitation in continental, midlatitude regions is a complex measure atmospheric dynamics and regional climate variability can be preserved geologic archives. However, continuous modern observations δ18O many regions, particularly the coastal western United States, are sparse. Here, tree-ring cellulose from southern California used to assess potential this proxy as an indicator long-term hydroclimate variability. From 1954 2004, we observed that was well replicated within single stand blue oak (Quercus douglasii) on interannual decadal time scales. By using forward mechanistic model, demonstrate not driven solely by composition at site nor any other variable. Instead, prior 1979 positively correlated with growing season soil water after negatively relative humidity. In addition, 2 years (1983 1998) anomalously low coincided wettest strongest El Nino events late 20th century. For these years, decreased near surface evaporation and/or increased upper-level condensation could account for more depleted values. While sensitive variability, varying temporal correlation between different environmental variables complicates attempt use isotopes reconstructions beyond calibration period.