Rotational vibrational-rotational Raman differential absorption lidar for atmospheric ozone measurements: methodology...

Area of Science:

• Atmospheric Science
• Lidar Technology
• Spectroscopy

Background:

• Accurate ozone measurements are crucial for understanding atmospheric chemistry and climate.
• Conventional Raman differential absorption lidar (DIAL) techniques face challenges with cloud-particle scattering, affecting measurement accuracy.
• Existing lidar systems often require multiple lasers, increasing complexity.

Purpose of the Study:

• To propose and evaluate a single-laser Raman DIAL system for ozone measurements.
• To specifically enable ozone measurements within clouds, a challenging environment for lidar.
• To reduce the complexity and wavelength-dependent scattering effects in lidar measurements.

Main Methods:

• Utilized a single injection-locked XeCl excimer laser as the radiation source.
• Employed anti-Stokes rotational Raman scattering for on-resonance ozone absorption.
• Used vibrational-rotational Raman backscattering as the off-resonance wavelength.
• Developed a rotational vibrational-rotational (RVR) Raman DIAL setup with a narrow-band interference-filter polychromator receiver.

Main Results:

• Model calculations indicate a 70-85% reduction in cloud-particle scattering effects compared to conventional Raman DIAL.
• Demonstrated single-laser ozone measurements in the troposphere and lower stratosphere.
• Showcased the potential for ozone measurements within clouds with improved receiver performance.

Conclusions:

• The proposed RVR Raman DIAL system offers a substantial improvement in measuring ozone in the presence of clouds.
• The single-laser approach simplifies the lidar apparatus.
• Further advancements in receiver technology can enable robust in-cloud ozone profiling.