Journal of Climate, vol. 5, no. 7, July 1992
Tree-Ring Density Reconstructions of Summer Temperature Patterns across Western North America since 1600
K.R. Briffa, P.D. Jones, F.H.Schweingruber
Summer half-year (April-September) mean temperatures are reconstructed across western North America
between 1600 and 1982. The reconstructions, ultimately in the form of gridpoint anomaly time series, are
produced using a principal-components regression technique to relate variability in a network ofup to 53 high-elevation
maximum latewood-density chronologies to a number of important temperature principal-component
amplitude series. The reconstructions are of good quality over the area between 35° and 55°N but are subject
to large uncertainty north of 55°N, particularly prior to 1750. Four regional time series, the average of between
two and six gridpoint series - British Columbia and the Pacific Northwest, California, eastern Rockies and
northern High Plains, and the Southwest deserts - plus one more-extensive western United States series are
presented and described. Examples of individual-year and decadal-mean anomaly maps are illustrated, and the
results of preliminary spectral analyses of the regional time series are described.