Retrieval of Atmospheric Aerosol and Trace Gas Vertical Profiles using Multi-Axis Differential Optical Absorption Spectroscopy

Abstract

In this thesis, the vertical distribution of atmospheric trace gases and aerosols were retrieved using Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). Various inversion methods were used to retrieve the profiles from the MAX-DOAS measurements. A new MAX-DOAS instrument optimized for the measurement of aerosol and trace gas profiles was developed. The retrieval methods were tested and advanced in the scope of the EUSAAR (European Supersites for Atmospheric Aerosol Research) project. Several intercomparison campaigns were carried out in Cabauw (the Netherlands), Ispra (Italy) and Leipzig/Melpitz (Germany). Aerosol extinction and NO2 profiles were retrieved from the MAX-DOAS measurements and compared to independent in situ and remote sensing measurements. Good agreements were achieved for both the aerosol and NO2 profiles. Furthermore, the diluted plume of the Eyjafjallajokull volcano, Iceland, was detected by MAX-DOAS SO2 measurements over Heidelberg in April and May 2010. These measurements showed an unambiguous detection of SO2, and are in agreement with satellite observations and model predictions. The here presented advances in instrumental hardware and retrieval algorithms demonstrate that MAX-DOAS is a powerful tool for monitoring the vertical distribution of atmospheric constituents. Verified by independent measurements, its integration in worldwide measurement networks is recommended.