HR: 1340h
AN: PP43A-0592    [Abstracts]
TI: Record of the Southwest Monsoon from Gulf of Mexico Sediment Cores
AU: * Grissino-Mayer, H D
EM: grissino@utk.edu
AF: Department of Geography, University of Tennessee, Knoxville, Tn 37996 United States
AU: Poore, R Z
EM: rpoore@usgs.gov
AF: U.S. Geological Survey, 600 4th Street South, St. Petersburg, Fl 33701 United States
AU: Pavich, M J
EM: mpavich@usgs.gov
AF: U.S. Geological Survey, MS 926A 12201 Sunrise Valley Drive, Reston, Va 20192 United States
AU: Quinn, T M
EM: quinn@seas.marine.usf.edu
AF: College of Marine Sciences, 140 Seventh Ave South University of South Florida, St. Petersburg, Fl 33702 United States
AB: Summer monsoonal rains are an important source of moisture to portions of southwestern United States and northern Mexico. Changes in the amount and seasonal distribution of precipitation in this semi-arid region of North America influence overall water supply and severity of fires. Historical records demonstrate that precipitation in the southwestern U.S. is quite variable, but the long-term (millennial-scale) variability of the monsoon system is not well known. Studies based on tree rings can provide highly resolved records of past conditions, but separating temperature and precipitation signals can be difficult, and determining seasonality of precipitation is challenging. In addition, tree-ring records usually represent short intervals of the Holocene, and they often reflect local conditions. In this study, we show that variations in the abundance of the planktic foraminifer Globigerinoides sacculifer in marine sediments from the Gulf of Mexico are a proxy for the southwest monsoon on millennial and sub-millennial time scales. The marine record confirms a severe multi-century drought centered at ~ 1600 calendar years BP as well as several multidecadal droughts that have been identified in a long tree-ring record spanning the last 2000 calendar years from west-central New Mexico. Analyses of the marine and tree-ring records indicate that decadal- and century-scale changes in monsoon intensity are related to solar variability. The marine monsoon proxy provides the potential for constructing a highly resolved, well-dated, and continuous history of the southwest monsoon for the entire Holocene.
DE: 4267 Paleoceanography
DE: 3309 Climatology (1620)
DE: 1600 GLOBAL CHANGE (New category)
DE: 1650 Solar variability
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting