HR: 17:45h
AN: PP54A-08    [Abstracts]
TI: Seasonally Resolved Climate Records from Puerto Rico over the Past Eight Centuries
AU: * Kilbourne, K H
EM: hali@marine.usf.edu
AF: Univ. South Florida, College of Marine Science, 140 7th Ave. S., St. Petersburg, FL 33707 United States
AU: Quinn, T M
EM: tquinn@marine.usf.edu
AF: Univ. South Florida, College of Marine Science, 140 7th Ave. S., St. Petersburg, FL 33707 United States
AU: Nyberg, J
EM: johan.nyberg@sgu.se
AF: Sveriges Geologiska Undersökning, Box 670, Upsala, SE-751 28 Sweden
AU: Winter, A
EM: awinter@ucsd.edu
AF: Univ. Puerto Rico, Department of Marine Sciences P.O Box 9013, Mayaguez, PR 00681 Puerto Rico
AU: Webb, R S
EM: robert.s.webb@noaa.gov
AF: NOAA/OAR/Climate Diagnostics Center, 325 Broadway, Boulder, CO 80305 United States
AU: Guilderson, T
EM: tguilderson@llnl.gov
AF: CAMS, Lawrence Livermore National Laboratory, P.O. Box 808, L-397, Livermore, CA 94550 United States
AB: Sedimentary archives of southern and eastern Caribbean climate from both terrestrial and marine environments indicate a trend of increased aridity over the last millennium, a trend that is often attributed to the southward displacement of the mean ITCZ position during this time. It is hypothesized that this mean climate shift is caused by changes in the seasonal patterns of ocean-atmosphere interactions, but sub-annually resolved climate records available to test this theory are sparse. A suite of coral samples from La Parguera, Puerto Rico has been analyzed for Sr/Ca and δ¹⁸O to investigate surface ocean conditions over the past 800 years. One continuous core, which was collected in August 2004, extends back to 1750 AD and was sampled at key time intervals based on a density band chronology. Another coral core contains a discontinuous record dating back to 1171±32 AD based on uranium series age determinations. Coral samples representing each of the past eight centuries are available from these cores. The records generated to date are characterized by a trend of decreasing coral δ¹⁸O from the 12^th century to the present. The -0.58‰ magnitude of the trend is equivalent to nearly +3 °C or -3 psu if interpreted as solely temperature or solely salinity, but the actual changes are likely to be a combination of the two variables and thus much smaller in magnitude. There is no discernible long-term trend in coral Sr/Ca and the mean Sr/Ca has much less variability than observed in the coral δ¹⁸O, indicating that changes in hydrologic balance dominate SST changes over the past eight centuries. During the beginning of the Little Ice Age (circa 1450-1650), coral δ¹⁸O values sharply decreased to near modern values while the Sr/Ca values increased. Such a trend is consistent with cooling and/or cooling/drying in this region during the LIA. We explore the mechanism(s) responsible for our observations as well as linkages with other Caribbean climate records.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4504 Air/sea interactions (0312, 3339)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4916 Corals (4220)
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005