Instrumental climate records indicate that drought patterns in western North America are sensitive to Pacific Ocean variability and to interactions between the El Niño Southern Oscillation, and the North American monsoon. A deeper understanding of the past behavior of these modes is needed to improve predictions of future drought and pluvial cycles. This proposed research would: 1) provide proof of concept for the use of delta-Deuterium records in lake systems where single phase carbonates are not available for delta-18 Oxygen analyses and 2) add to a growing a network of quantitative paleoclimate data sets that would add a critical spatial and temporal perspective to our understanding of aridity patterns in western North America and associated synoptic climate teleconnections.
The proposed project will develop lake sediment organic matter del-D records from two closed-basin lakes at centennial scale from two drought-sensitive lakes in the western US for the last 2,000 years. The first, Castor Lake, is a well-studied system in Washington State that has been instrumented for a decade with lake level sensors, water temperature loggers, sediment traps, a weather station, and annual ground, lake and stream sampling for water chemistry and stable isotopes. A decadal scale record of oxygen isotopes has been published from Castor Lake, and offers an opportunity for comparison with Algal del-D. The second lake, Graham Lake, is also a drought-sensitive system located in New Mexico, a region of great interest for drought studies. The team has visited this system, verified that it meets the criteria for their proposed work and plans to recover a series of overlapping cores for this study.
The broader impacts are that if this new del-D technique is successful in these lakes without single phase carbonates, the resulting network of paleodrought datasets from the western US would provide important new information on the timing, duration and magnitude of wet/dry cycles and combined with ongoing research, identify spatial patterns of aridity in North America during late Holocene.
