Stratospheric polar vortex shapes Arctic surface climate via a radiative pathway

Area of Science:

• Climate Science
• Atmospheric Physics
• Arctic Meteorology

Background:

• The stratospheric polar vortex (SPV) influences winter surface climate via dynamical coupling.
• A less recognized mechanism involves SPV strength modulating Arctic high clouds and surface radiative effects.

Purpose of the Study:

• To investigate the radiative pathway through which SPV variations affect Arctic high clouds and surface climate.
• To quantify the impact of this radiative mechanism on Arctic warming and sea ice loss.

Main Methods:

• Analysis of SPV strength variations.
• Investigation of associated Arctic high-cloud cover changes.
• Numerical experiments to quantify radiative effects on Arctic Ocean warming.

Main Results:

• A strengthened SPV increases Arctic high-cloud cover, leading to amplified warming and sea ice loss in the Barents-Kara Sea.
• A weakened SPV produces opposing effects.
• Numerical experiments show up to 1.7 K Arctic Ocean warming during strong SPV events due to this radiative pathway.

Conclusions:

• The radiative pathway involving Arctic high clouds is a primary driver of winter-mean Arctic climate response to stratospheric variability.
• This radiative influence is more persistent than dynamical coupling, enhancing predictive potential for Arctic surface conditions.
• Understanding this mechanism is crucial for present and future winter Arctic climate change assessments.