OXYGEN ISOTOPES IN TREE-RING CELLULOSE AS A PROXY FOR TROPICAL CYCLONE ACTIVITY, SOUTH CAROLINA

The 2005 hurricane season, which saw the impacts of Hurricanes Katrina, Wilma and Rita, was the busiest and most costly on record. Over the past decade, hurricane frequency has been on the rise, however, long-term trends and variability in hurricane occurrence are still poorly understood. Current records of tropical cyclone activity include modern instrumental and historical records (newspapers, ship logs, plantation diaries, HURDAT). Natural proxies such as coastal pond sediments, tree-ring and speleothem isotopic compositions have also been developed. Tree-ring proxies are unique due to their high-resolution and exact placement in time. Recent research in southern Georgia has demonstrated the potential use of seasonally-resolved oxygen isotope compositions of tree-ring α-cellulose as a proxy for recording hurricane activity. It is important to evaluate this proxy in areas with different climate or hurricane histories and geologic substrates. Here, we present two isotope time series where hurricane occurrence and precipitation are verified with the modern instrumental record for the period 1945-2000. Trees collected and analyzed come from Francis Marion National Forest (FMNF) and Sandy Island, South Carolina. Compared to the previous study (Valdosta, Georgia), the isotopic time series for the FMNF site preserves a similar record of long-term climate but a different accounting of hurricanes. South Carolina presents a unique opportunity to verify the isotope proxy beyond the instrumental record because recent efforts provide detailed information on tropical cyclone activity back into the 18th century.