HR: 08:30h
AN: U41B-03    [Abstracts]
TI: Long-term Drought in the North-Western Interior of North America and Linkages to ENSO, PDO and AMO
AU: * Sauchyn, D J
EM: sauchyn@uregina.ca
AF: Prairie Adaptation Research Collaborative, # 150 - 10 Research Dr. University of Regina, Regina, SK S4S7J7, Canada
AU: Barichivich, J
EM: campsidium@YAHOO.COM
AF: Laboratorio de Dendrocronología, Instituto de Silvicultura, Universidad Austral de Chile, Valdivia, Chile
AB: The subhumid climate of North America's western interior extends to high latitudes in the rainshadow of the western Cordillera. Higher temperatures in this region in recent decades are consistent with global warming scenarios that also include increased summer aridity. This drier climate most likely will result from a greater frequency of severe or prolonged drought. The instrumental observation of climate, extending only to late 19th century at a few sites, provides a limited perspective on long-term hydroclimatic variability. Most drivers of the variation in hydroclimate have a periodicity that approaches or exceeds the length of instrumental records. Among sources of paleo-climatic data, tree-rings are among the best proxies of summer and annual hydroclimate and drought. In the Tree-Ring Lab at the University of Regina, we have developed a network of more than 60 moisture-sensitive tree-ring chronologies spanning the western interior from the island forests of eastern Montana, up the foothills of the Canadian Rockies and across the boreal forest of Alberta, Saskatchewan and the Northwest Territories. Most of the tree-ring samples are from open-canopy forests sites at dry sites, where available soil moisture controls tree growth. This tree-ring network enables us to examine the variability of hydroclimate over the past 250-750 years and 19 degrees of latitude. Correlations between principal components and global SSTs and SLP reveal responses of tree growth to ENSO, PDO and AMO. This comparative wavelet analysis indicates that moisture variability at interannual (2-7 yr) and decadal to interdecadal (15-25 yr) timescales is strongly linked to SSTs in the Pacific Ocean (i.e. ENSO and PDO), while multidecadal variability (30-70 yr) is mainly related to the AMO. These forcings of hydroclimate and their interactions modulate to a great extent the moisture variability in this region at various temporal and spatial scales. The application of our paleo-drought records to water resource management in western Canada is one aspect of the knowledge translation strategy at the Prairie Adaptation Research Collaborative; PARC supports collaborations among scientists and decision makes to address adaptation to climate change. An important finding of our tree-ring research with management implications is the distinct hydroclimatic cycles with wavelengths that are near or just beyond the length of gauge records. Also the non-stationarity of linkages between drought and SSTs indicates that forcing of hydroclimatic variability identified from the analysis of instrumental records may apply only to recent decades. Western water policy, use and management practices have evolved during a period of fairly reliable water supplies and under assumptions of relatively abundant water and stationary hydroclimate. The low frequency cycling of hydroclimate will underlie the trends imposed by global warming: lower summer stream flows, falling lake levels, and increasingly frequent soil and surface water deficits. Between cycles and trends, our experience with practitioners is that they more comfortable with historical and proxy data records derived from tangible archives as opposed to simulated shifts in future climate. Thus the tree-ring reconstructions of streamflow and drought serve to expand the perspective of water managers beyond the range of conventional experience and databases before they are asked to comprehend and apply scenarios of the hydroclimate of the mid 21st century.
UR: http:www.parc.ca/urtreelab
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1620 Climate dynamics (0429, 3309)
DE: 1630 Impacts of global change (1225)
DE: 1637 Regional climate change
DE: 1655 Water cycles (1836)
SC: Union [U]
MN: 2007 Joint Assembly