Reconstruction of nineteenth century summer temperatures in Norway byproxy data from farmers' diaries.

摘要

Proxy data from five farmers' diaries in the More, Dovre and Trondelag regions in central Norway were used for climatic reconstruction purposes. The method chosen was "simple linear regression analysis" with the start of the grain harvest (barley or oats) as predictor and summer temperature (May August) as predictand. Overlapping periods with modern instrumental observations (starting 1858 or later) were used for calibration of the model. The model was tested on independent data by establishing the regression on one half of the overlapping period and applying the regression on the other half. The standard deviation in the residuals varied from 0.3 degreesC to 0.7 degreesC and the biases of the mean values from -0.3 degreesC to +0.3 degreesC. Climatic reconstructions were established for the early- and mid-nineteenth century summer temperature, i.e. during the last part of what has come to be regarded as the "Little Ice Age", in this article considered to end around 1880.