Meridional flow variability over the Nordic Seas in the Arctic oscillation framework



An anomalous recurring atmospheric circulation pattern of high relevance for the climate of the Nordic Seas and Siberia is identified. It is found as the second Empirical Orthogonal Function (EOF) of monthly winter sea level pressure (SLP) anomalies poleward of 30°N where the leading EOF is the Arctic Oscillation (AO). The most prominent centre of action of the circulation pattern is located over the Barents Region. This “Barents Oscillation” (BO) is shown to have a high temporal correlation with the sensible heat loss of the Nordic Seas (r=0.76). The BO also correlates to Eurasian surface air temperature (SAT) anomalies with r=0.72 after the AO related SAT variations are removed by means of a linear regression. Two sets of SLP composites are constructed where one is based on low and high Nordic Seas heat loss months and the other is based on warm and cold Eurasian months. Patterns reminiscent of the BO emerge in the two composites when AO related variability is removed.