Complimenting modern records of tropical cyclone activity with longer historical and paleoclimatological records would increase our understanding of natural tropical cyclone variability on decadal to centennial timescales. Tropical cyclones produce large amounts of precipitation with significantly lower δ¹⁸O values than normal precipitation, and hence may be geochemically identifiable as negative δ¹⁸O anomalies in marine carbonate δ¹⁸O records. This study investigates the usefulness of coral skeletal δ¹⁸O as a means of reconstructing past tropical cyclonic events. Isotopic modeling of rainfall mixing with seawater shows that detecting an isotopic signal from a tropical cyclone in a coral requires a salinity of ∼33 psu at the time of coral growth, but this threshold is dependent on the isotopic composition of both fresh and saline end-members. A comparison between coral δ¹⁸O and historical records of tropical cyclone activity, river discharge, and precipitation from multiple sites in Puerto Rico shows that tropical cyclones are not distinguishable in the coral record from normal rainfall using this approach at these sites. This study highlights the importance of understanding the coastal zone tropical cyclone isotopic signal and the importance of choosing a climate proxy organism that will continue to calcify in the face of tropical cyclone related disturbances.

Hali Kilbourne earned a Bachelor's degree in Geology from Smith College and a Master's and Ph.D. in Marine Science from the University of South Florida. After spending time at NOAA-ESRL as a National Research Council postdoctoral fellow and as a visiting Assistant Professor at McDaniel College, she is currently a Research Assistant Professor at the University of Maryland Chesapeake Biological Laboratory. Her broad research area covers understanding past climate variability in order to improve projections of future responses to anthropogenic climate change. She has most recently been focused on the history of multidecadal-scale climate variability in the Atlantic and on synthesizing paleoclimate records of the last two millenia with a data assimilation approach.

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