The link between eddy-driven jet variability and weather regimes in the North Atlantic-European sector

Abstract

This study reconciles two perspectives on wintertime atmospheric variability in the North Atlantic–European sector: the zonal‐mean framework comprising three preferred locations of the eddy‐driven jet (southern, central, northern), and the weather regime framework comprising four classical North Atlantic‐European regimes (Atlantic ridge AR, zonal ZO, European/Scandinavian blocking BL, Greenland anticyclone GA). A k‐means clustering algorithm is used to characterize the two‐dimensional variability of the eddy‐driven jet stream, defined by the lower tropospheric zonal wind in the ERA‐Interim reanalysis. The first three clusters capture the central jet and northern jet, along with a new mixed‐jet configuration; a fourth cluster is needed to recover the southern jet. The mixed cluster represents a split or strongly tilted jet, neither of which is well described in the zonal‐mean framework, and has a persistence of about one week, similar to the other clusters. Connections between the preferred jet locations and weather regimes are corroborated – southern to GA, central to ZO, and northern to AR. In addition, the new mixed cluster is found to be linked to European/Scandinavian blocking, whose relation to the eddy‐driven jet was previously unclear.