East Asian synoptic climatology linked to Atlantic multidecadal variability.

Area of Science:

• Climatology
• Atmospheric Science
• Meteorology

Background:

• The Atlantic Multidecadal Oscillation (AMO) is a significant climate pattern with observed historical data.
• The AMO has demonstrated potential links to global synoptic climatic shifts and can be utilized for climate prediction.
• Understanding the AMO's influence on regional weather patterns is crucial for long-term forecasting.

Purpose of the Study:

• To investigate the impact of AMO-induced alterations in the East Asian westerly jet stream on weather patterns.
• To analyze the influence of the AMO on the frequency of winter cold surges and late summer typhoons.
• To assess the feasibility of long-term synoptic climatology predictions for East Asia based on the AMO timescale.

Main Methods:

• Utilized cluster analysis to examine weather pattern frequencies from 1941 to 2021.
• Analyzed the relationship between AMO phases and the occurrence of cold surges and typhoons.
• Investigated shifts in the upper-tropospheric westerly jet stream position.

Main Results:

• During negative AMO phases, a southward shift in the westerly jet stream was observed.
• This shift led to an inverse change in winter cold surge frequencies: increased wave-train surges and decreased blocking surges.
• A more pronounced wave pattern and southward jet stream shift in late summer correlated with an increased frequency of typhoons.

Conclusions:

• AMO-induced jet stream shifts significantly impact East Asian weather patterns, including cold surges and typhoons.
• Long-term predictions of East Asian synoptic climatology on an AMO timescale appear feasible.
• The study highlights the AMO as a key factor in understanding and predicting regional climate variability.