Ozone and carbon monoxide budgets over the Eastern Mediterranean

Area of Science:

• Atmospheric Chemistry and Transport
• Environmental Science
• Climate Modeling

Background:

• The Eastern Mediterranean is a region susceptible to air pollution influenced by long-range transport (LRT).
• Understanding the budgets of key pollutants like ozone (O3) and carbon monoxide (CO) is crucial for assessing air quality.
• The interplay between the boundary layer (BL) and the free troposphere (FT) in pollutant distribution requires detailed investigation.

Purpose of the Study:

• To investigate the importance of long-range transport (LRT) on ozone (O3) and carbon monoxide (CO) budgets in the Eastern Mediterranean.
• To differentiate the contributions of LRT from Western Mediterranean and regional anthropogenic sources to air quality.
• To project future changes in O3 and CO levels based on emission scenarios.

Main Methods:

• Utilized the state-of-the-art 3-dimensional global chemistry-transport model TM4-ECPL.
• Performed a 3-D budget analysis, distinguishing between the Eastern and Western Mediterranean basins.
• Separated pollutant contributions within the boundary layer (BL) and the free troposphere (FT).

Main Results:

• The free troposphere (FT) over the Eastern Mediterranean acts as a significant receptor of polluted air masses from the Western Mediterranean.
• The FT is the primary source of O3 and CO for the Eastern Mediterranean boundary layer (BL), contributing approximately 40%.
• Regional anthropogenic sources have a minor impact, contributing only 8% to surface O3 and 18% to surface CO.

Conclusions:

• Long-range transport, particularly from the FT, is the dominant factor controlling O3 and CO levels in the Eastern Mediterranean.
• Regional anthropogenic emissions play a secondary role in the overall air quality of the region.
• Future projections indicate a decrease in surface O3 (11%) and an increase in surface CO (10%) by 2050, neglecting climate change impacts.