Past hydroclimate extremes in Europe driven by Atlantic jet stream and recurrent weather patterns

Area of Science:

• Atmospheric Science
• Climate Science
• Paleoclimatology

Background:

• The Atlantic jet stream significantly impacts European weather and climate, influencing temperature extremes, moisture transport, and atmospheric blocking.
• Climate change may alter jet stream characteristics, but its long-term variability is poorly understood.

Purpose of the Study:

• To analyze the interannual-to-decadal variability of the Atlantic-European jet stream's strength, tilt, and latitude over the past 600 years (1421–2023).
• To investigate the relationship between jet stream variability and European drought and flood occurrences.

Main Methods:

• Utilized an ensemble of monthly and daily atmospheric field reconstructions to derive jet stream indices.
• Compared jet variability with historical data on blocking frequency, cyclonic activity, and drought/flood records.

Main Results:

• A poleward-shifted jet correlates with enhanced summer drought in Central Europe.
• An equatorward-shifted jet, linked to reduced blocking, is associated with frequent winter floods in Western Europe and the Alps.
• Volcanic eruptions significantly influence jet stream strength and tilt.
• Recent jet stream index changes fall within the natural variability observed over the past six centuries.

Conclusions:

• Jet stream position and strength are key drivers of European drought and flood patterns over long timescales.
• Recent increases in flood and drought frequency are not attributable to changes in the jet stream's recent variability.
• Volcanic activity has a notable impact on jet stream dynamics.