Insights into the 100 largest European surface ozone episodes during spring-summer 2003-2022

Area of Science:

• Atmospheric chemistry and physics
• Air quality monitoring
• Climate science

Background:

• Ozone episodes pose significant air quality challenges in Europe.
• Previous studies have not fully elucidated the regional drivers of large-scale ozone events.
• The Copernicus Atmosphere Monitoring Service provides valuable reanalysis data for studying atmospheric phenomena.

Purpose of the Study:

• To investigate the spatial distribution and key drivers of major ozone episodes across Europe.
• To analyze the influence of meteorological conditions and precursor emissions on ozone episodes in specific European regions.
• To identify regional differences in the factors contributing to high ozone concentrations.

Main Methods:

• Utilized a semi-Lagrangian algorithm to detect 100 large-scale ozone episodes from 2003-2022.
• Employed an atmospheric blocking and subtropical ridge identification method.
• Analyzed data for three distinct regions: British Isles (BRIT), Eastern Europe (EEU), and Central Europe (CEU).

Main Results:

• Eastern Europe episodes linked to anticyclonic conditions and precursor emissions, often from wildfires.
• British Isles episodes associated with negative geopotential height anomalies, cooler temperatures, and stronger winds.
• Central Europe showed north-south differences: northern regions influenced by blocks/ridges, southern regions by subsidence and weaker synoptic forcing.

Conclusions:

• Ozone episode occurrence is determined by region-specific combinations of meteorological factors and precursor availability.
• Findings highlight the need for tailored air quality management strategies based on regional characteristics.
• This study advances understanding of extreme ozone event formation in Europe.