Dendroclimatic reconstruction of precipitation for sites in the southern Canadian Rockies

Abstract

Seven Douglas fir ( Pseudotsuga menziesii) tree-ring chronologies were developed from sites in Banff and Jasper National Parks, Alberta, and near Cranbrook, British Columbia. The chronologies ranged in length from 191 to 691 years and display a strong precipitation signal. Multiple regression models were developed that calibrate .50% of the variance in the instrumental records and were used to reconstruct annual (pAugust– July or pJuly–June) precipitation for Banff, Jasper and Cranbrook. Comparison of these reconstructions with records from adjacent areas indicates that periods of reduced precipitation occurred over this region in c. ad 1760–1775, the 1790s, the 1840s–1870s, the 1890s and c. 1920–1945. Periods of significantly greater precipi-tation occurred during the 1880s–1920s and in the latter half of the twentieth century. The Banff reconstruction extends back to ad 1430 and also shows major drier intervals c. 1470–1510, the 1570s and 1615–1660. These reconstructions indicate regionally coherent precipitation patterns that fluctuate on decadal timescales and may be linked to changes in atmospheric circulation patterns.