HR: 15:10h
AN: GC43B-06    [Abstracts]
TI: The record and forcing of paleodrought in western North America: extrapolation from the western US to western Canada
AU: * Sauchyn, D J
EM: sauchyn@uregina.ca
AF: Prairie Adaptation Research Collaborative, # 150 - 10 Research Drive University of Regina, Regina, SK S4S 7J7, Canada
AU: Barichivich, J
EM: campsidium@yahoo.com
AF: Prairie Adaptation Research Collaborative, # 150 - 10 Research Drive University of Regina, Regina, SK S4S 7J7, Canada
AU: Suzan, L
EM: lapp200s@uregina.ca
AF: Prairie Adaptation Research Collaborative, # 150 - 10 Research Drive University of Regina, Regina, SK S4S 7J7, Canada
AB: Much of the classic paleodrought research is based on networks of tree-ring chronologies from the western US and in particular the southwest. This extensive work has established the timing, severity and causes of drought across the region over the past millennium. Even though some of this literature implies that the findings extend to western North America, they may or may not apply to western Canada which is beyond the influence of the North American monsoon. On the basis of this previous work, we hypothesize that in western Canada (i) severe drought is linked to negative phases of ENSO (La Nina) and the PDO, and (ii) the growing season of about three months limits the tree-ring proxy to a signal of summer climate. We test these hypotheses using data from our network of more than 60 tree-ring chronologies extending from northeastern Montana to the southern Northwest Territories across Canada's western Interior; a subhumid region where drought represents Canada's most damaging natural hazard. Our results do not support these hypotheses. At many sites the tree-rings capture a signal of spring and even winter precipitation. The spatial and temporal association between these seasonal moisture signals and large-scale climate forcings is quite complex and reveals that, in contrast to the US southwest, moisture deficits correlate in general with positive phases of the ENSO and PDO, and there is a strong non- stationary multidecadal hydroclimatic signal likely related to the AMO and/or PDO. These periodic low-frequency hydroclimate signals are also evident in the climate variability simulated by GCMs for this region. Our ongoing research is focused on the time-varying relationships between the climate forcings and drought, and in the changes in the pattern of teleconnections of drought in the western interior of Canada and ENSO between phases of PDO and AMO.
UR: http://www.parc.ca/urtreelab/
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1637 Regional climate change
DE: 1655 Water cycles (1836)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3344 Paleoclimatology (0473, 4900)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting