Interannual to multidecadal Euro‐Atlantic blocking variability during winter and its relationship with extreme low temperatures in Europe

Abstract

The dominant modes of blocking frequency variability in the Atlantic-European region are evaluated for the 1871-2010 period. An Empirical Orthogonal Function (EOF) analysis of a two-dimensional blocking indicator field reveals three dominant EOFs, describing about 35% of interannual to multidecadal blocking variability. The first EOF captures an out-of-phase blocking frequency anomaly over Greenland and Western Europe regions. The corresponding principal component time series is strongly correlated with the North Atlantic Oscillation index but shows also significant correlations with indices of the East Atlantic, Scandinavian, and East Atlantic-Western Russia patterns. The second EOF shows a dominant center over the North Sea region as well as a less pronounced center with anomalies of the same sign over southeastern Greenland. The multidecadal variations of this mode of blocking variability are related with a basin wide North Atlantic sea surface temperature anomaly which projects partly on the Atlantic Multidecadal Oscillation (AMO). The third mode is an east-west dipole of blocking frequency anomalies from Scandinavian and southern Greenland regions and shows enhanced variability at~20 year time scales. The coherent variations of the time coefficients of this pattern with open solar flux suggest a possible solar influence on blocking variability at these time scales. Furthermore, the dominant patterns of blocking variability are related with distinct anomaly patterns in the occurrence of extreme low temperature events over Europe at interannual to multidecadal time scales. AMO as well as the solar signals was detected also in the corresponding extreme low temperature blocking patterns. We argue that multivariate analysis of blocking indicators gives additional information about blocking and related extreme climate phenomena variability and predictability comparative with classical sectorial approach.

Links between central Greenland stable isotopes, blocking and extreme climate variability over Europe at decadal to multidecadal time scales

“…Similar results were obtained in previous studies (e.g. Scherrer et al 2006;Rimbu et al 2014). The differences between absolute values of blocking frequency in 20CR (Fig.…”

“…The modeled NAO index is calculated as the PC1 of the linearly detrended and normalized winter SLP from the North Atlantic region (90°W-40°E; 20°N-80°N). Furthermore, we used also the PCs associated with the dominant patterns of blocking in the North Atlantic region during the 1871-2010 period, described in Rimbu et al (2014). The time series of the Atlantic Multidecadal Oscillation (AMO) index, defined as the area weighted average of the North Atlantic (0-70°N) sea surface temperature anomalies, was downloaded from the Earth System Research Laboratory (ESRL) web page (http://www.esrl.noaa.gov/psd/data/correlation/amon.us.long.data).…”

Links between blocking circulation and precipitation extremes over Romania in summer

“…This suggests that blocking activity and related extreme precipitation are modulated by internal or external forcing as suggested in recent studies (e.g. Rimbu et al, 2014).…”

Can tree-ring density data reflect summer temperature extremes and associated circulation patterns over Fennoscandia?

“…Moreover, as temperature extremes are usually closely linked with specific circulation patterns, such as atmospheric blockings (Rimbu et al 2014;Ionita et al 2015), studies of long-term extreme variability can also be helpful when assessing the history of certain type of atmospheric circulation patterns in a region.…”