HR: 16:45h
AN: GC44A-04    [Abstracts]
TI: Does the PDO Affect the Climate over Greenland and Complicate the Reconstruction of NAO Variability from Ice Core Records?
AU: * Mosley-Thompson, E S
EM: thompson.4@osu.edu
AF: Byrd Polar Research Center, The Ohio State University, 1090 Carmack Road, Columbus, OH 43210 United States
AU: * Mosley-Thompson, E S
EM: thompson.4@osu.edu
AF: Department of Geography, The Ohio State University, Columbus, OH 43210 United States
AU: Readinger, C R
EM: creadinger@aurora.gsfc.nasa.gov
AF: Science Systems and Applications Inc., 10210 Greenbelt Road, Suite 600, Lanham, MD 20706 United States
AU: Thompson, L G
EM: thompson.3@osu.edu
AF: Byrd Polar Research Center, The Ohio State University, 1090 Carmack Road, Columbus, OH 43210 United States
AU: Thompson, L G
EM: thompson.3@osu.edu
AF: Department of Geological Sciences, The Ohio State University, Columbus, OH 43210 United States
AU: Lin, P
EM: lin.25@osu.edu
AF: Byrd Polar Research Center, The Ohio State University, 1090 Carmack Road, Columbus, OH 43210 United States
AU: Bathke, D J
EM: djbathke@msn.com
AF: Byrd Polar Research Center, The Ohio State University, 1090 Carmack Road, Columbus, OH 43210 United States
AB: Efforts to use ice core paleoclimate histories to extend the record of North Atlantic climate variability, characterized as the North Atlantic Oscillation (NAO), have met with mixed results. An expanded data set of annually resolved, multi-century records, reveals that the relationship between NAO variability and annual accumulation over Greenland varies both spatially and temporally. Prior to 1925 when the amplitude of the NAO was large and its periodicity was more regular, its influence on accumulation was strongest in west central Greenland (r = -0.735, sig. $>$ 95%). As the NAO weakened and became less periodic (i.e., from 1925 to 1960), its influence on accumulation shifted to southeastern Greenland (r = -0.497, sig. $>$ 95%). A preliminary investigation of the relationship between the variability in the Pacific Decadal Oscillation (PDO) and ice-core derived annual $\delta$$^{18}$O and accumulation histories (1900 to 1999 A.D.) suggests that the PDO may exert a greater influence on North Atlantic climate variability than hitherto considered. The cool season (Nov. - Mar.) PDO and annual accumulation in southern Greenland were strongly correlated (r = -0.680, sig. $>$ 95%) prior to 1945. In 1945 the PDO changed from a warm to a cool phase and thereafter the relationship with accumulation weakened. Most intriguing is the strong positive relationship between the cool season PDO and annual average $\delta$$^{18}$O that characterized the region stretching from the central summit (GISP2) to the northwest (GITS) prior to 1945. After the Pacific phase change in 1945, the statistically significant relationship between $\delta$$^{18}$O and PDO shifted southeast and changed sign (negative). These observations suggest a century scale north-south seesaw in the influence of PDO on the $\delta$$^{18}$O signature in Greenland precipitation, but confirmation awaits reconstruction of a longer PDO history.
DE: 9315 Arctic region
DE: 3344 Paleoclimatology
DE: 1827 Glaciology (1863)
DE: 1600 GLOBAL CHANGE (New category)
DE: 1620 Climate dynamics (3309)
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting