Impact of Solar Proton Events on the Stratospheric Polar Vortex in the Northern Hemisphere: A Quantitative Analysis

The stratospheric polar vortex (SPV) profoundly affects northern hemisphere weather and climate, with its dynamics influenced by terrestrial and solar factors. Despite established terrestrial influences, the quantitative effects of solar energetic particles have not yet been fully understood. This study presents a quantitative analysis of 27 intense solar proton events (SPEs) from 1986 to 2020, revealing a significant correlation between the integrated flux of SPEs and enhanced SPV wind speeds across altitudes. Notably, the wind speed enhancements, ranging from 1.8 m/s (15.1%) at 100 hPa to 3.0 m/s (7.3%) at 1 hPa, demonstrate an altitude-dependent pattern, with the greatest impacts of 5.8 m/s (19.1%) at 5 hPa. A partial correlation analysis identifies SPEs as the dominant driver of SPV enhancement in the middle and lower stratosphere, while ultraviolet radiation dominates at the stratopause. We propose a mechanism involving the amplification of the meridional temperature gradient due to differential ozone responses, thereby linking solar activity to the modulation of the SPV. These findings enhance our understanding of solar-terrestrial interactions and their implications for climate modeling.