HR: 0800h
AN: PP31A-1500    [Abstracts]
TI: Intercomparison of Speleothem and Lake Geochemical Proxy Records for Interpreting Paleoydrologic Conditions on Sub-Tropical North America During the Late Holocene
AU: * Hollander, D J
EM: davidh@marine.usf.edu
AF: University of South Florida, College of Marine Sceince 140 7th Ave. S., St. Petersburg, FL 33701 United States
AU: Soto, L
EM:
AF: University of South Florida, Deptartment of Geology, Tampa, FL 33620
AU: Polk, J
EM:
AF: University of South Florida, Environmental Sciene and Policy, Tampa, FL 33620
AU: Van Beynen, P
EM: vanbeynen@cas.usf.edu
AF: University of South Florida, Environmental Sciene and Policy, Tampa, FL 33620
AB: Late Holocene climate variability includes the cold Little Ice Age (LIA) and the Medieval Warm Period (MWP). During these abrupt climate events, continental hydrologic conditions are expected to have varied considerably, especially in the sub-tropics of North America, where tropical climate and temperate climate regimes interact seasonally and vary over longer time periods. Interactions between the ITCZ, Bermuda high, meridional jet stream, and northern frontal systems result in seasonal hydrologic trends whereas longer-term changes in hydrologic conditions includes influences associated with the Atlantic Multidecadal Oscillation, El Nino intentsity and solar forcing. Unraveling the complicated meteorological interactions between seasonal and longer-term controls on continental hydrologic conditions are critical for quantitative reconstructions and for developing water resource management strategies. Ongoing isotopic calibration studies in modern Lake Tulane and the Brooksville cave in central Florida indicate that dD of lake organic mater and d18O of speleothem carbonates quantitatively record changing hydrologic conditions. This research integrates the results of the calibration studies with high-resolution (decadal-scale) lake sediment and cave speleothem records in order to evaluate meteorological controls on continental hydrology during MWP and the LIA. Inter-comparisons of the cave and lake records reveal strong coherence throughout the Late Holocene and that, relative to modern times, the MWP period was characterized by increased precipitation, greater input from southern air-masses, warmer water lake waters (4°C), and increased relative humidity (78 o/o). In contrast, the LIA relative to today shows cooler lake temperatures (2°C), reduced relative humidity (65 o/o), and reduced amounts of precipitations and a greater influence of northern air masses. Results of this study will be discussed in terms of the complex interplay of meteorological factors controlling hydrologic conditions in sub-tropical North America.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1630 Impacts of global change (1225)
DE: 1637 Regional climate change
DE: 4215 Climate and interannual variability (1616, 1635, 3305, 3309, 4513)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005