Towards quantitative atmospheric water vapor profiling with differential absorption lidar

Area of Science:

• Atmospheric remote sensing
• Laser spectroscopy
• Trace gas analysis

Background:

• Differential Absorption Lidar (DIAL) is a key technique for atmospheric trace gas profiling.
• Current DIAL systems require highly accurate wavelength stabilization and spectroscopic parameters.
• Active development is ongoing to enhance DIAL system precision and operational range.

Purpose of the Study:

• To present a novel master laser system for robust wavelength stabilization in DIAL.
• To highlight the impact of laser spectral purity on DIAL accuracy.
• To describe a new method for measuring effective absorption cross-sections.

Main Methods:

• Development of a master laser system for stabilizing multiple side-line laser wavelengths.
• Utilizing an absorption cell (33 m path length) for laser stabilization and cross-section measurement.
• Employing microwave beat-frequencies for off-line laser stabilization and quantitative number density measurements.

Main Results:

• Demonstrated a novel laser system capable of stabilizing multiple wavelengths for DIAL.
• Presented a calibration technique to determine effective absorption cross-sections.
• Achieved preliminary results using nanojoule pulses at 822.922 nm with a photomultiplier tube receiver.

Conclusions:

• The novel laser system and calibration techniques significantly enhance DIAL system accuracy and stability.
• The developed methods pave the way for probing trace gases at greater atmospheric altitudes.
• Improved spectral purity and accurate cross-section measurements are crucial for advanced DIAL applications.