Jim Hurrell, Senior Scientist
Climate Indices ->Introduction to NAO Indices
Winter (Dec-Mar) Station Based NAO Index
Available Formats: HTML Table | ascii | Microsoft Excel File (.xls)
Winter (December through March) index of the NAO based on the difference of normalized sea level pressure (SLP) between Lisbon, Portugal and Stykkisholmur/Reykjavik, Iceland since 1864. The SLP anomalies at each station were normalized by division of each seasonal mean pressure by the long-term mean (1864-1983) standard deviation. Normalization is used to avoid the series being dominated by the greater variability of the northern station. Positive values of the index indicate stronger-than-average westerlies over the middle latitudes.
The station data were originally obtained from the World Monthly Surface Station Climatology.
