Extended Data Figure 1: 2-, 4- and 8-node SOM analyses.
From: Contribution of changes in atmospheric circulation patterns to extreme temperature trends
SOM-derived mid-atmospheric summer (JJA) circulation patterns (500 hPa geopotential height anomalies) over Europe using 2- (a), 4- (b) and 8-node (c) analyses. White boxed values show pattern frequencies in the top left and SOM node numbers in the top right. Time series of SOM circulation pattern occurrence (black (d yr−1)), persistence (blue (d event−1)) and maximum duration (red (d event−1)). The slope of the trend line (yr−1) and P values (in parentheses) are colour coded, with the values from 1979 to 2013 (solid trend line) displayed above those from 1990 to 2013 (dashed trend line). Statistically significant trends (5% significance level; Methods) are shown by bold fonts in the scatter plots. Geopotential height fields are sourced from the NCEP-DOE-R2 reanalysis33.
