SOUTH EASTERN UNITED STATES MILLENIAL PRECIPITATION RECONSTRUCTION FROM A FLORIDIAN SPELEOTHEM

Little is known about the paleo-precipitation history of the Floridian Peninsula. A speleothem collected Ocala, Florida, yields such a record for the last millennia. The stalagmite possesses a stable isotopic record of annual to decadal resolution determined using TIMS U-series analyses. Variations in the δ¹⁸O composition reveal abrupt changes in precipitation amount, fluctuations that appear both regional and hemispheric in nature. A strong correlation between calcite δ¹⁸O and the SE US tree-ring record (surrogate for spring precipitation - Stahle and Cleaveland, 1992) suggests a regional atmospheric influence. Migration in the mean position of the North Atlantic High is one such possibility. Movement of the High to the east brings wetter conditions to the Peninsula. However, a strong similarity between the speleothem δ¹⁸O record and changing El Niño intensity (NINO3 – Cane 2005) provides another explanation. The hemispheric nature of the changing precipitation arises from a close match between the above records and the Cariaco Basin Ti record (Huag et al. 2001) which records variable continental runoff. Such comparisons provide a near immediate teleconnection between the tropics and subtropics. The coupled migration of the ITCZ and the North Atlantic High would provide such a connection.