Dendroclimatology in the Northeastern United States

Canonical correlations and regressions were calculated between a set of 7 tree-ring width chronologies and a set of 12 temperature or 15 precipitation records from the northeastern United States. The regressions calibrated 38.5% of the winter temperature variance, 26.5% of the winter precipitation variance, 20.9% of the spring precipitation variance in the dependent period, 1905-1960. The regression equations were then applied to the 275-year record of the 7 tree-ring chronologies to obtain estimates of past temperature and precipitation. Reconstructions wee tested for statistical verification with climatic data not used in the regressions, and the series that showed highest verification in each season was selected for further study. The best winter temperature reconstruction passed 50% of the verification tests, the best winter precipitation reconstruction passed 12.5% of the tests, and the best spring precipitation reconstruction passed 26.8% of the tests. The reconstructions of the stations which passed the most verification tests in each season were averaged, and the regional averages were smoothed and plotted. These presented as a first, tentative approximation of past climate.