HR: 1340h
AN: PP33B-1575    [Abstracts]
TI: Strengthening of PDO-like multi-decadal drought recurrence during the early Holocene: a high-resolution diatom record from the Northern Rocky Mountains
AU: * Stone, J R
EM: jstone@unlserve.unl.edu
AF: University of Nebraska-Lincoln, 214 Bessey Hall Department of Geosciences, Lincoln, NE 68566-0340 United States
AU: Fritz, S C
EM: sfritz2@unl.edu
AF: University of Nebraska-Lincoln, 214 Bessey Hall Department of Geosciences, Lincoln, NE 68566-0340 United States
AB: The diatom stratigraphy of Foy Lake, Montana is one of a very small number of continental records of sufficient resolution and length to detect patterns of change in severe multi-decadal drought recurrence throughout the entire Holocene. Time-series analysis of a decadally-resolved 13,000-year record suggests that the Holocene Thermal Maximum is a period of persistent drought cyclicity, inferred from regular (50-70yr) and pronounced oscillations between two dominant diatom groups representing deeper and shallower lake conditions. The onset of persistent multi-decadal drought cyclicity in the record is coincident with major changes in the boundary conditions at the end of the Last Glacial Maximum as a cooler, more stable climate is replaced by recurrent drought with frequencies similar to 20th century multi-decadal phase changes of the Pacific Decadal Oscillation. This multi-decadal variability is overprinted on millennial-scale oscillations, inferred to represent broad changes in the effective moisture of the Northern Rocky Mountains throughout the mid-Holocene. As solar insolation continued to wane, the pattern of multi-decadal drought became less stable, attenuating at approximately 4,500 years B.P.
DE: 0458 Limnology (1845, 4239, 4942)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1812 Drought
DE: 3344 Paleoclimatology (0473, 4900)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005