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A Midwinter Minimum in North Atlantic Storm Track Intensity in Years of a Strong Jet

2017; American Geophysical Union; Volume: 44; Issue: 24 Linguagem: Inglês

10.1002/2017gl075136

1944-8007

Hilla Afargan‐Gerstman, Yohai Kaspi,

Tropical and Extratropical Cyclones Research

Abstract This study investigates the occurrence of a midwinter suppression in synoptic eddy activity within the North Atlantic storm track. It is found that eddy kinetic energy over the Atlantic is reduced during winter relative to fall and spring, despite the stronger wintertime jet and enhanced baroclinicity. This behavior is similar to the well‐known Pacific midwinter minimum, yet the reduction over the Atlantic is smaller and persists for a shorter period. To examine the conditions favorable for this phenomenon, we present an analysis of years with stronger jet intensity versus years of weaker jets over the Atlantic and Pacific basins. When the wintertime jet is stronger, the midwinter suppression of eddy activity is more pronounced, and the jet is more equatorward. Since the climatological Atlantic jet is weaker relative to the Pacific jet, the conditions for a midwinter suppression in the Atlantic are generally less favorable, yet a midwinter suppression often occurs in years of a strong jet.