HR: 1340h
AN: PP13C-1414    [Abstracts]
TI: Coherent vertical changes in North Pacific climate dynamics during the last millennium
AU: * Kreutz, K J
EM: karl.kreutz@maine.edu
AF: Climate Change Institute, 236 Sawyer Hall University of Maine, Orono, ME 04469, United States
AU: Osterberg, E
AF: Climate Change Institute, 236 Sawyer Hall University of Maine, Orono, ME 04469, United States
AU: Wake, C
AF: Climate Change Research Center, Morse Hall University of New Hampshire, Durham, NH 03824, United States
AU: Yalcin, K
AF: Department of Geosciences, Oregon State University, Corvallis, OR 97331, United States
AU: Fisher, D
AF: Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada
AU: Mayewski, P
AF: Climate Change Institute, 236 Sawyer Hall University of Maine, Orono, ME 04469, United States
AU: Introne, D
AF: Climate Change Institute, 236 Sawyer Hall University of Maine, Orono, ME 04469, United States
AU: Handley, M
AF: Climate Change Institute, 236 Sawyer Hall University of Maine, Orono, ME 04469, United States
AU: Sneed, S
AF: Climate Change Institute, 236 Sawyer Hall University of Maine, Orono, ME 04469, United States
AU: Whitlow, S
AF: Climate Change Research Center, Morse Hall University of New Hampshire, Durham, NH 03824, United States
AB: Understanding the forcing and spatial response of Late Holocene North Pacific climate remains a challenge, particularly with respect to changes that may have occurred in the vertical structure of the atmosphere. Ice core records recovered from different elevations in the St. Elias Mountains (Eclipse Icefield, 3000 masl; PR Col, 5200 masl) reveal similar changes in atmospheric circulation and hydrology over the past 1000 years. Sodium concentrations at both sites calibrated to the strength of the wintertime Aleutian Low increase after ~1250 AD, suggesting on average a deeper low pressure system in the North Pacific during the Late Holocene. At the same time, stable isotope data from the Eclipse ice core display a classic Little Ice Age (LIA)/Medieval Climate Anomaly (MCA) pattern; that is, lower isotope ratios during the LIA, and higher isotope ratios during the MCA. Regardless of the scaling used on the Eclipse isotope data (e.g., temperature, hydrology, or some combination), a distinct drop in isotope ratio occurs just prior to 1200AD, which in general corresponds to the observed changes in sodium records as well as many Pacific paleohydrology records. The coherence of this 13th century change in both the horizontal and vertical sense appears to strengthen arguments related to the El Nino Southern Oscillation, namely that changes in volcanic and solar forcing caused a shift from predominately La Nina conditions during the MCA to predominately El Nino conditions during the LIA.
DE: 0776 Glaciology (1621, 1827, 1863)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1610 Atmosphere (0315, 0325)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1620 Climate dynamics (0429, 3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting