Dendroclimatic reconstruction of precipitation for sites in the southern Canadian Rockies

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 precipitation 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.