Abstract ATM-9308300 Shen, Glen T. Title: Pacific Paleoclimate from Reef Corals in the Eastern and Western Margins: Records from Galapagos, Cocos Island and the Gulf of Papua This award will support a study designed to characterize the paleoclimate of the eastern Pacific over the last 400 years using the best available coral samples and seeks to establish a new geochemical tracer in the far western Pacific - a region for which few marine climatic indicators presently exist. The foci of the eastern Pacific reconstructions will be the Galapagos Islands (0.5oS, 91oW) and Cocos Island (5.3oN, 86.9oW). The ratio of barium:calcium in coral argonite, a sensitive indicator of upwelling and fluvial discharge, will be the key measurement using an Inductively-Coupled Plasma Mass Spectrometer (ICP-MS). Records spanning 270- (Cocos) and 400-years (Galapagos) length will be produced at quarter-annual resolution. Additionally, annual determinations of Cd/Ca and Mn/Ca will be made . Developmental effort for a regional precipitation index over Australasia will involve determination of Ba/Ca ratios in a 100- year coral core from the Gulf of Papua, an area markedly influenced by Ba-enriched continental runoff. The goal of this work is the development of climatically-relevant datasets which surpass the instrumental record in length yet retain the quality of latter 20th century measurements. Such records will allow a closer examination of recurrent periods (e.g annual, biennial, and three-to-seven year ENSO timescales) which appear to characterize the lower atmosphere and upper ocean, and may reveal the existence of longer time scale variations.
