AbstractsEarth & Environmental Science

The North Atlantic Oscillation (NAO) is the major mode of atmospheric winter variability over the North Atlantic. Its current state has long been described by the station‐based NAO Index. This index has been shown to represent winter temperature anomalies over Northern Europe well. Nonetheless, its positions of measurement are stationary and may not catch the moving NAO-pattern’s characteristics sufficiently well to best represent the Scandinavian winter temperature anomalies. A new index based on North Atlantic maximum and minimum sea level pressure (SLP) is introduced in this study (called NAOE Index). The points of NAOE Index are therefore moving over the North Atlantic SLP‐field and may better catch atmospheric processes affecting Scandinavian winter temperature anomalies. NAOE Index correlation with Scandinavian winter temperature anomalies is analyzed through NASA’s (National Aeronautics and Space Administration) MERRA‐data (Modern Era‐Retrospective analysis forResearch and Applications). This study shows that NAOE Index represents the Scandinavian winter temperature anomalies almost as well as NAO Index from observed values does. The indices are alsowell correlated with each other. The direct difference between maximum and minimum SLP is also analyzed with regard to the Scandinavian winter temperature anomalies. The SLP‐differences are class‐divided and their correlations to the class‐mean temperature anomaly are shown to be very high. This correlation issignificantly higher than the correlations of temperature and each index. Hence, the results from this study suggest that an index based on the direct extreme‐SLP‐difference is preferred for representing the NAO’s impact on Scandinavian winter temperature anomalies. This study gives additionally a comprehensive view of NAO. Studies concerning the NAO’s history of research, dynamics, temperature connections and secondary impacts are reviewed.