A Revisit of Large-Scale Patterns in Middle Stratospheric Circulation Variations

Area of Science:

• Atmospheric Science
• Climatology
• Aerospace Engineering

Background:

• Stratospheric circulation variations significantly influence tropospheric weather and climate.
• Understanding these dynamics is crucial for improving weather forecasts and guiding stratospheric aircraft operations.
• Despite progress, a comprehensive view of large-scale stratospheric circulation patterns remains elusive due to its complex nature.

Purpose of the Study:

• To analyze large-scale stratospheric circulation patterns using the eigen microstate approach (EMA).
• To investigate the temporal characteristics of stratospheric zonal wind variations from 1980-2022.
• To identify potential links between stratospheric circulation cycles and external factors like the solar cycle.

Main Methods:

• Utilized ERA5 reanalysis data for zonal wind analysis between 70-10 hPa.
• Applied the eigen microstate approach (EMA) to identify dominant circulation modes.
• Filtered high-frequency components to reveal underlying cyclical patterns.

Main Results:

• Identified three leading modes: quasi-biennial oscillation (QBO) strength, Arctic, and Antarctic stratospheric circulation.
• Observed a significant 11-year cycle in Antarctic circulation, potentially solar-driven, and a 5-6 year cycle in Arctic circulation.
• A Southern Hemisphere dipole mode correlated with Antarctic circulation, leading by two months. A predictive model for the Antarctic polar vortex was developed.

Conclusions:

• Stratospheric circulation exhibits distinct regional cycles, with the Antarctic susceptible to solar influences due to later polar vortex breakdown.
• The identified cycles and correlations offer insights into atmospheric predictability.
• The developed linear model demonstrates potential for predicting Antarctic polar vortex behavior.