Retrieval of tropospheric ozone profiles using ground-based MAX-DOAS

Area of Science:

• Atmospheric Chemistry
• Remote Sensing
• Environmental Science

Background:

• Surface ozone concentrations are rising in Chinese cities.
• Multi-axis differential optical absorption spectroscopy (MAX-DOAS) is effective for trace gas profiling but struggles with stratospheric ozone interference.
• Few studies have retrieved tropospheric ozone profiles using MAX-DOAS.

Purpose of the Study:

• To develop an accurate inversion method for retrieving tropospheric ozone profiles using MAX-DOAS.
• To analyze ozone pollution characteristics during the PRIDE-GBA Campaign.
• To investigate the control mechanisms of planetary boundary layer ozone pollution.

Main Methods:

• Developed an inversion method to retrieve tropospheric ozone concentrations.
• Utilized QDOAS software for ozone differential slant column densities (DSCDs) retrieval.
• Subtracted simulated stratospheric DSCDs from total DSCDs to obtain tropospheric DSCDs (DSCDs_trop).
• Employed the optimal estimation method (OEM) for profile retrieval.
• Validated results with lidar and in-situ measurements.

Main Results:

• High tropospheric ozone concentrations were primarily found below 1 km.
• Retrieved surface ozone concentrations showed high correlation with in-situ measurements (R=0.75 and 0.81).
• Combined MAX-DOAS NO₂ and HCHO profiles indicated a NO_x-limited regime for ozone pollution at HeShan Observatory.

Conclusions:

• The developed MAX-DOAS method accurately retrieves tropospheric ozone profiles.
• MAX-DOAS shows significant potential for high temporal and spatial resolution ozone profile monitoring.
• Understanding ozone pollution drivers is crucial for effective air quality management.