HR: 11:10h
AN: GC11A-04 INVITED     [PDF]
TI: Mount Logan Ice Core Evidence for Secular Changes in the Climate of the North Pacific Following the End of the Little Ice Age
AU: * Moore, K
EM: moore@atmosp.physics.utoronto.ca
AF: University of Toronto, 60 St. George Street, Toronto, On M5S 1A7 Canada
AU: Alverson, K
EM: keith.alverson@pages.unibe.ch
AF: PAGES International Project Office, Sulgeneckstrasse 38, Bern, 3007 Switzerland
AU: Holdsworth, G
EM: gholdswo@ucalgary.ca
AF: University of Calgary, 2500 University Drive N.W, Calgary, AB T2N 1N4 Canada
AB: The relatively short length of most instrumental climate datasets restricts the study of variability and trends that exists in the climate system. This is particularly true regarding the atmosphere where high quality spatially dense data exists only since the late 1940s. With this data, the Pacific North America pattern (PNA) has been identified as one of the dominant modes of variability in the atmosphere that plays an important role in the climate of North America. This pattern consists of alternating regions of high and low geopotential height anomalies in the middle and upper troposphere arching from the tropical Pacific to North America. It is thought to be the result of a standing Rossby wave pattern forced by the upper-atmospheric convergence associated with the descending branch of the regional Hadley Circulation. We will describe the climate signal contained in a 301-year ice core record from a high elevation site on Mount Logan in the Yukon. This record has a statistically significant and accelerating positive trend in snow accumulation from the middle of the 19th century, the end of the Little Ice Age. As we will show, this record contains an expression of the Pacific North America (PNA) teleconnection as well as the regional Hadley and Walker circulations in the Pacific. We argue that the positive trend in snow accumulation in the ice core is a reflection of secular changes in the intensities of these circulations that has ongoing since the end of the Little Ice Age.
DE: 1620 Climate dynamics (3309)
DE: 3309 Climatology (1620)
DE: 3344 Paleoclimatology
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting