Locations of the sediment cores collected during Knorr Cruise KNR176-2 we intend to use for the proposed paleoclimate study:
KNR176-2 32JPC (4.40°N; 77.58°W; 2195 m water depth)
KNR176-2 12GGC (5.27°N; 77.42°W; 1845 m water depth)
KNR176-2 13JPC (5.27°N; 77.42°W; 1837 m water depth)
KNR176-2 36JPC (6.38°N; 77.47°W; 1240 m water depth)
KNR176-2 03JPC (7.17°N; 78.15°W; 2137 m water depth)
KNR176-2 41JPC (7.06°N; 80.32°W; 1498 m water depth)
KNR 176-2 44GGC (6.42°N; 81.28°W; 1832 m water depth)
KNR176-2 46JPC (6.42°N; 81.28°W; 1821 m water depth)
Locations of core MD02-2529 (Leduc et al., 2007) and ODP Site 1241 (Benway et al., 2006) are shown for comparison. The Rio San Juan delta is indicated by a white arrow. Inset: El Niño minus La Niña composite of annual-mean precipitation (mm/day) constructed from the years where the annual-mean SST in the Nino1+2 region over the period 1979-2007 is at maximum (1983, 1987, 1997, 1998) and minimum (1985, 1988, 1996, 2007), respectively. Data source: CPC Merged Analysis of Precipitation (Xie and Arkin, 1997).
The tropical eastern Pacific is a key area for monitoring climate variability, as it is highly sensitive to ITCZ (Intertropical Convergence Zone) and ENSO (El Nino-Southern Oscillation) dynamics. A sequence of new sediment cores from high deposition rate locations along the Colombian and Panamanian margins thus provides an opportunity to improve our understanding of the role of the tropical hydrological cycle as a potential driving force for global climate change. Using stable isotope and trace metal analyses on planktonic foraminifera as well as organic geochemical tracers and Accelerator Mass Spectrometer (AMS) C-14 dating, we will develop a history of sea surface temperature and salinity changes, thermocline depth and river runoff in the Panama Bight, covering the last glacial termination and the Holocene. Mapping of temporal changes in the spatial hydro-climatic patterns within the study area will provide unprecedented information about ITCZ shifts and ENSO-like climate changes. The proxy studies will be accompanied by simulations of Holocene and deglacial climate states, using a high-resolution version of the comprehensive climate model CCSM3. The model results will help to interpret the proxy records and to set them into a global dynamical context. In particular, the model will provide quantitative information about changes in the Atlantic-to-Pacific water vapor flux, while the proxy records will be indispensable for verifying the model output.
Stable isotope analyses of planktonic foraminifera, Mg/Ca and alkenone paleothermometry, Branched and Isoprenoid Tetraether (BIT) index, AMS C-14 dating, coupled climate modelling
Marine records from the Panama Bight
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