Ozone differential absorption lidar algorithm intercomparison.

Area of Science:

• Atmospheric Science
• Remote Sensing
• Lidar Technology

Background:

• The Network for the Detection of Stratospheric Changes (NDSC) utilizes differential absorption lidar (DIAL) for ozone monitoring.
• Accurate ozone profile retrieval is crucial for understanding stratospheric changes and long-term trends.

Purpose of the Study:

• To intercompare various ozone DIAL algorithms used within the NDSC.
• To assess the accuracy and vertical resolution of these algorithms in retrieving ozone number density from lidar signals.
• To identify limitations of DIAL algorithms in different stratospheric regions.

Main Methods:

• Processing of synthetic lidar signals based on Rayleigh scattering and predefined ozone profiles.
• Inclusion of perturbed ozone profiles to test algorithm response to variations.
• Simulation of signal-to-noise ratio degradation with altitude.

Main Results:

• Lidar algorithms showed low bias (<1%) below 30 km for unperturbed profiles.
• Significant biases (up to 10% at 45 km) were observed in the upper stratosphere.
• Algorithm performance degraded with altitude due to decreased signal-to-noise ratio and increased smoothing.
• Vertical resolution estimation showed inconsistencies among participating lidar teams.

Conclusions:

• Ozone DIAL algorithms perform well in the lower and middle stratosphere but face challenges in the upper stratosphere.
• Increased vertical smoothing, necessary for low signal-to-noise ratios, compromises the detection of ozone perturbations.
• Current lidar systems may have limitations in detecting long-term ozone trends above 40 km.
• Standardization of vertical resolution estimation in lidar data processing is needed.