HR: 0800h
AN: PP21A-1366    [Abstracts]
TI: Mount Logan Ice Core Evidence For Changes In The Hadley And Walker Circulations Following The End Of The Little Ice Age
AU: * Holdsworth, G
EM: gholdsworth@ucalgary.ca
AF: University of Calgary, 2500 University Drive N.W., Calgary, ON T2N 1N4 Canada
AU: Moore, K
EM: moore@atmosp.physics.utoronto.ca
AF: University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 Canada
AU: Moore, K
EM: moore@atmosp.physics.utoronto.ca
AF: University of Calgary, 2500 University Drive N.W., Calgary, ON T2N 1N4 Canada
AU: Alverson, K
EM: k.alverson@unesco.org
AF: Intergovernmental Oceanographic Commission, 1, rue Miollis, Paris, ON 75732 France
AB: The Hadley and Walker circulations dominate the climate of the tropics and contribute to extra-tropical climate variability through the forcing of planetary waves that result in the long-range correlation of atmospheric circulation patterns known as teleconnections. Previous work showed that an annually resolved 301-year ice core record of annual snow accumulation from a high elevation site on Mount Logan in northwestern North America contains an expression of one such teleconnection, the Pacific North America (PNA) pattern. Here we show that this record contains a related signal associated with the regional Hadley and Walker circulations in the Pacific. We argue that the positive trend in snow accumulation in the ice core that started in the middle of the 19th century is a reflection of changes in the intensities of these circulations that has been ongoing since the end of the Little Ice Age. This change may also be associated with the observed jump in $\delta^{18}$O that occurred in the ice core as well as in a number of widely spaced tropical coral records around the same time.
DE: 9355 Pacific Ocean
DE: 3344 Paleoclimatology
DE: 1833 Hydroclimatology
DE: 1040 Isotopic composition/chemistry
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting