Multispectrum analysis of the oxygen A-band

Area of Science:

• Atmospheric Science
• Spectroscopy
• Remote Sensing

Background:

• Accurate atmospheric composition retrieval relies on precise airmass quantification.
• Oxygen (O2) A-band spectroscopy is crucial for airmass normalization in carbon dioxide (CO2) retrievals, as seen in the OCO-2 mission.
• Achieving 0.25% CO2 accuracy necessitates state-of-the-art oxygen spectroscopy.

Purpose of the Study:

• To develop an integrated, self-consistent spectroscopic model for accurate oxygen A-band cross-section measurements.
• To incorporate advanced line-shape models, line mixing (LM), and collision-induced absorption (CIA) for comprehensive modeling.
• To create an improved, high-accuracy spectroscopic database for atmospheric composition studies.

Main Methods:

• Utilized Fourier Transform Spectroscopy (FTS) and Cavity Ring-Down Spectroscopy (CRDS) for complementary data acquisition.
• Developed a sophisticated line-shape model, including Rautian or Speed-Dependent Voigt, LM, and CIA.
• Employed multispectrum fitting software to generate a new, accurate spectroscopic database.

Main Results:

• Generated a comprehensive new database of oxygen A-band cross-sections with improved accuracy.
• Integrated multiple spectroscopic phenomena (line-shape, LM, CIA) into a self-consistent model.
• Combined data from FTS and CRDS to enhance model dynamic range and minimize systematic errors.

Conclusions:

• The developed integrated spectroscopic model and database significantly enhance the accuracy of atmospheric airmass determination.
• The new ABSCO (airmass-dependent cross-section) table and parameterization will be made available for use in databases like HITRAN.
• This work advances the state-of-the-art in oxygen spectroscopy, crucial for precise atmospheric composition retrievals.