Tree-ring Reconstruction of Early-growing Season Precipitation from Yellowknife, Northwest Territories, Canada

Twelve jack pine (Pinus banksiana) tree-ring chronologies were developed from sites on rock outcrops near Yellowknife, Northwest Territories, Canada. The average chronology length is approximately 180 years spanning the period 1825-2005. The longest extends to 1679, whereas the shortest covers the period 1936-2005. All of the site chronologies are significantly correlated with June, total May-July, June-July, and June-August precipitation, although relations with the single month of June are strongest. June precipitation was reconstructed using a regionally averaged tree-ring chronology. The reconstruction captures 42% of the variance in the instrumental climate record and based on Rbar and EPS statistics is considered robust from 1819 to 2005. Periods of lower June precipitation occurred in 1927-1979, 1880-1893, 1842-1865, 1801-1821, 1776-1796, and 1698-1739. Positive June precipitation anomalies are reconstructed for 1980-1995, 1890-1926, 1822-1841, 1756-1775, and 1687-1697. Throughout the period of reconstruction, there is strong multi-decadal agreement between June precipitation in Yellowknife and other dendrohydrological records from western North America and records of Pacific climate variability. This suggests that large-scale atmospheric patterns influenced by sea surface temperatures (SSTs) in the Pacific basin have controlled continental-scale precipitation patterns at decadal time scales in the Yellowknife region over the past three centuries or more.