Dominant modes of climate variabilities in the North Atlantic region from Emperical Orthogonal Analysis of Sea Level Pressure anomaly during 1993-2016

A large amount of atmospheric and oceanic exchange between the Arctic and lower latitudes take places through the North Atlantic region. We present three dominant modes of large scale atmospheric circulation variability in this region that primarily affects the exchange processes between the Arctic and lower latitudes. Empirical orthogonal function (EOF) analysis of the de-trended monthly sea level pressure (SLP) anomaly from the ECMWF ERA-Interim data shows the first three modes of the variability and their corresponding time series for the period 1993-2016. They are identified as North Atlantic Oscillation (NAO), East Atlantic Pattern (EAP) and Scandanavian Pattern (SCAN) (Chakif et al., 2017). These three modes together explain about 68% (34.3%, 17.3% and 16.4 % respectively) of the total variance in the SLP anomaly and thus can be considered as the primary features of the large scale circulation in this region. Interactions among these three modes also have significant impacts on the regional to remote climate variabilities (Moore et al., 2013).