The Atlantic Jet and European Hydroclimate Extremes During the Past 600 Years

Abstract

The jet stream over the Atlantic-European sector is relevant for weather and climate in Europe. It generates temperature extremes, steers moisture and flood-propelling weather systems to Europe or allows blocks to develop and persist leading to drought. Climate change might alter the jet characteristics affecting weather extremes. However, little is known about its interannual-to-decadal variability in the past. In this contribution we present an analysis of strength, tilt, and latitude of the Atlantic-European jet during the past 600 years in a comprehensive monthly climate reconstruction and compare their variability with drought and flood reconstructions in Europe. Summer drought is enhanced in Central Europe in periods with a poleward-shifted jet. An analysis of decadal flood variability shows that flood-rich periods in the warm season in the Alps coincide with an equatorward-shifted jet. In the cold season, a strong jet increases precipitation in Northern Europe, whereas an equatorward-shifted jet leads to frequent floods in Western Europe. Jet position, tilt, and strength are significantly influenced by El Niño and volcanic eruptions, but overall, the forced component is weak. The jet characteristics provide both a mechanism and a diagnostic to analyse decadal hydroclimate variability in Europe. Our 600-year perspective shows that recent changes in the jet are still within the past variability when considering ensemble members separately.