RECONSTRUCTING STORM HISTORY IN COASTAL ENVIRONMENTS: IMPORTANCE OF LONG, HIGH-RESOLUTION RECORDS FOR CLIMATE PREDICTION

Existing historical records of tropical cyclones in the North Atlantic are inadequate to assess the skill of numerical models forecasting hurricane occurrence in the future. Although the identity and the relative influence of meteorological forces responsible for the development of hurricanes continue to be debated, most scientists agree that many of these key processes vary over decadal and longer time periods. Discerning relevant climate variables that drive hurricane development using traditional harmonic analysis techniques therefore requires a much longer, high-resolution time series, particularly when attempting to tune predictive models for long-term forecasts related to global warming. We present a new methodology for reconstructing such a storm history for the Eastern Caribbean using both the geologic record and early historical accounts. Flood deposits resulting from heavy rainfalls spawned by passing tropical systems (tropical wave – hurricane) are examined at multiple locations across the Eastern Caribbean. Criteria used to select study sites include 1) geographic location across traditional hurricane paths, 2) predominant rainfall events derived from tropical systems, and 3) natural catchment ponds. Sediment cores collected from natural catchment ponds show layers of flood deposits, defined by oxidation bands and grain size, strongly correlate to documented hurricanes. Chronological control over the last 350 years is obtained using both traditional radioisotopes as well as a more novel technique that quantifies the relative abundance of black carbon preserved in the sediment. Wavelet analyses suggest strong recurrence frequencies of 30 years and 70 years, in both the historical storm record and the sediment cores. Our reconstructed cyclone history spans 500 years, from the 16^th through the 20^th century. The time period with the highest frequency of storms was the 19^th century; the 17^th and early 20^th centuries exhibited the lowest storm frequency.