Abstract ATM-9810474 Leavitt, Steven W. University of Arizona Title: Tree-Ring Formation, Isotopes, and El Nino in Ponderosa Pine of the Southwest Climate conditions and variability over several centuries in the American Southwest have been investigated via standard dendroclimatological research during the past few decades. Analysis of reconstructed data and modern instrumental data indicates this region's climate appears particularly impacted by El Nino teleconnections and the vagaries of the annual southwestern summer monsoon. New tools in the form of stable isotopes have recently become a viable option for probing present and past climate by means of analysis of tree rings and precipitation. This award supports a study designed to establish the linkage between tree-ring isotopic composition and environment (including climate). The primary focus of the proposed research will be to advance the numerical tree-ring growth process model through the addition of isotopic subroutines. The fundamental goal of the process model development is to take inputs of climate and isotopic composition of atmosphere and soil (water), and accurately generate the detailed patterns of isotopic variation (and cell size) for individual wood cells within rings. The isotopic experimentation and model development will go hand-in-hand to better understand relationships of isotopic composition and climate. With escalating use of tree-ring isotopes in climate research, especially at the subannual level, this model should provide important guidance to understanding the isotopic results.
