Particle backscatter and extinction profiling with the spaceborne high-spectral-resolution Doppler lidar ALADIN:...

Area of Science:

• Atmospheric Science
• Remote Sensing
• Lidar Technology

Background:

• The European Space Agency's Atmospheric Laser Doppler Instrument (ALADIN) is set for launch for global wind profile observations.
• ALADIN's capability to measure aerosol and cirrus optical properties, beyond wind, requires thorough investigation.
• Accurate optical property measurements are vital for understanding atmospheric composition and climate dynamics.

Purpose of the Study:

• To investigate the potential of the Atmospheric Laser Doppler Instrument (ALADIN) for measuring aerosol and cirrus optical properties.
• To develop and validate a comprehensive data analysis scheme for ALADIN's optical measurements.
• To assess the retrieval accuracy and uncertainties for particle backscatter, extinction coefficients, and lidar ratios.

Main Methods:

• Simulations were used to assess ALADIN's potential for optical property measurements.
• A data analysis scheme was developed, including cross-talk correction for Doppler-shifted particle backscatter interference.
• Independent retrieval procedures for volume extinction and backscatter coefficients were implemented, considering height-dependent signal resolution.

Main Results:

• Tropospheric aerosol and dust layers (50-200 Mm⁻¹ extinction) can be measured with 10%-15% error for backscatter, 15%-30% for extinction, and 20%-35% for lidar ratios.
• Cirrus clouds (>0.2 optical depth, 200 Mm⁻¹ extinction) allow retrieval of backscatter, optical depth, and column lidar ratios with 25%-35% uncertainty at 10 km resolution.
• Stratospheric aerosol layers and polar stratospheric clouds can be retrieved with 15%-30% uncertainty in backscatter coefficient.

Conclusions:

• ALADIN demonstrates significant potential for retrieving optical properties of aerosols and cirrus clouds, complementing its primary wind measurement function.
• The developed data analysis scheme provides reliable methods for accurate optical property retrieval with defined uncertainties.
• ALADIN's measurements will enhance our understanding of atmospheric composition, aerosol-cloud interactions, and climate processes.