Isotopic records of meteorological and atmospheric conditions from sub-annually resolved tree-ring cellulose, precipitation, and surface waters
Dodd, Justin Paul
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In recent decades, there has been increased global concern about observed climate change; however for future climatic impacts and anthropogenic forcings of climate change to be realistically predicted, natural climate variability in the past needs to be better understood. The aim of this research is to develop quantifiable proxy records of past climate change through the calibration of isotope values in modern surface waters and tree ring cellulose with meteorological and atmospheric records. Terrestrial proxy records that utilize oxygen and hydrogen isotope values to reconstruct paleoclimatic and paleohydrologic conditions are limited by a paucity of data on the modification of surface water isotope values prior to sequestration into proxy material. To address this gap in our knowledge and determine the most appropriate study sites, this research focuses on isotopic records preserved in surface water reservoirs, precipitation, and tree-ring cellulose. In the first study, δD, δ18O, and deuterium-excess values were determined for lakes and rivers from Tasmania, southeastern Australia. The second focus of this research was to calibrate the δ18O, δD, and δ13C values of tree-ring cellulose from North America with instrumental records. A new high-resolution sampling procedure that uses a robotic micromilling device to very precisely map and sample along growth rings in trees is discussed. Additionally, a seasonally resolved (early/late wood) 110-year record of δ18O values from tree-ring α-cellulose from spruce species (Picea mariana and P. glauca) from east-central Saskatchewan, Canada is compared to growing season precipitation δ18O values, temperature, and relative humidity. The δ18O time series from α-cellulose display a high correlation with growing season precipitation isotope values (r = 0.86). δ18O α-cellulose time series from a white spruce (Picea glauca) also records seasonal changes in atmospheric circulation associated with the position of the circumpolar vortex and dominate modes of atmospheric variability such as the North Atlantic Oscillation and Pacific Decadal Oscillation.
DegreeMaster of Science (M.Sc.)
SupervisorPatterson, William P.; Holmden, Chris
CommitteeBelanger, Nicolas; Basinger, James F.; Ansdell, Kevin M.
Copyright DateJune 2006