HR: 08:15h
AN: PP41C-02    [Abstracts]
TI: Phase Changes of the Winter North Atlantic Oscillation Recorded in Spatial Changes in Tree-Ring Patterns of North Aegean Oaks, AD 1190-1967
AU: * Griggs, C B
EM: cbg4@cornell.edu
AF: Cornell University, Earth and Atmospheric Sciences, Snee Hall, Ithaca, NY 14853 United States
AU: * Griggs, C B
EM: cbg4@cornell.edu
AF: Cornell University, The Malcolm and Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology, B48 Goldwin Smith Hall, Ithaca, NY 14853 United States
AU: DeGaetano, A T
EM: atd2@cornell.edu
AF: Cornell University, Earth and Atmospheric Sciences, Bradfield Hall, Ithaca, NY 14853 United States
AU: Kuniholm, P I
EM: pik3@cornell.edu
AF: Cornell University, The Malcolm and Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology, B48 Goldwin Smith Hall, Ithaca, NY 14853 United States
AU: Newton, M W
EM: mwn3@cornell.edu
AF: Cornell University, The Malcolm and Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology, B48 Goldwin Smith Hall, Ithaca, NY 14853 United States
AB: The low-frequency variance of the North Atlantic Oscillation (NAO) May index explains 91.6% of the variance in a filtered oak tree-ring chronology from the southern edge of the temperate zone in northeastern Greece and northwestern Turkey (39-42 degrees N, 22-37 degrees E) in the years 1916-1967. Before 1916, the complete oak chronology`s variance is not explained nearly as well by the May NAO. Analyses of the tree-ring data, divided west to east into three grids of 3 by 5 degrees latitude/longitude, indicate that the response to the May NAO in the western and eastern grids is moderated by changes in the effects of the winter (December-March) NAO and the Atlantic Multidecadal Oscillation (AMO) over the region. The two grids` growth patterns are the same between 1916-1967, but are opposed in an earlier range of years (1891-1915). From 1860 to 1890 the two grids` chronologies again have a synchronous response, but exhibit an opposing response from 1820 to 1860, and this relationship continues to switch back and forth over time. Running 24-year-window correlations between the two chronologies highlight the periods of the same or opposite effects over the region, and the years in which the relationship changes. The years of change tend to occur at times of multidecadal shifts in the phase of the winter (December-March) NAO index back into the middle of the 19th century and its reconstruction back into the late 17th century. The phase of the AMO at the time of the winter NAO phase change appears to have an influence on the intensity of their effects on the spatial gradient in the oak chronology response. With our robust 800-year filtered oak chronologies we are here reconstructing at least the times of change in phase of the winter NAO back to AD 1190. Current work on oak forest samples collected from the region in 2005 will allow us to update our data with a better analysis of the effect of the winter NAO and AMO at present and in the reconstruction.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1637 Regional climate change
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4914 Continental climate records
DE: 4920 Dendrochronology
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005