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yesterday

Mars’s Winter Polar Vortex Triggers Seasonal Ozone Buildup, Scientists Report

Researchers say ultra-cold, dry polar-night air lets ozone accumulate inside Mars’s north vortex.

Image
Perspective view of Mars’ north polar ice cap and its distinctive dark troughs forming a spiral-like pattern. The view is based on images taken by ESA’s Mars Express and generated using elevation data from the Mars Orbiter Laser Altimeter on board NASA’s Mars Global Surveyor. Image credit: ESA / DLR / FU Berlin / NASA / MGS / MOLA Science Team.

Overview

  • Observations indicate the vortex interior is about 40°C colder from near the surface up to roughly 30 km than surrounding air.
  • At these temperatures, scarce water vapor freezes onto the ice cap, removing the usual ozone-destroying chemistry and allowing ozone to surge.
  • The team combined ESA Trace Gas Orbiter ACS composition profiles with NASA Mars Climate Sounder temperature maps to target measurements inside the vortex.
  • Because the north polar region is in darkness during winter, measurements were possible when the vortex became distorted, offering a rare look into polar-night chemistry.
  • The findings were presented by Kevin Olsen and colleagues at the EPSC-DPS2025 meeting in Helsinki, with implications for models of past UV shielding and for ESA’s Rosalind Franklin rover mission planned for 2028.