Low and optically thin cloud measurements using a Raman-Mie lidar.

Area of Science:

• Atmospheric Science
• Cloud Physics
• Remote Sensing

Background:

• Accurate measurement of optically thin, low-altitude clouds during daytime is challenging.
• Existing lidar techniques can be affected by aerosol interference, limiting retrieval accuracy.

Purpose of the Study:

• To evaluate the capability of a Raman-elastic lidar system for daytime measurement of low-altitude optically thin clouds.
• To improve the accuracy of low-cloud optical depth retrievals by correcting for aerosol influences.

Main Methods:

• Utilizing nitrogen Raman and elastic-scattering returns for optical depth derivation.
• Applying a combined Raman-elastic lidar approach to correct for aerosol effects.
• Mapping lidar ratio profiles to assess cloud microphysical properties.

Main Results:

• Demonstrated significant improvement in Mie retrievals of low-cloud optical depth after aerosol correction.
• Achieved good agreement between corrected Mie retrievals and direct Raman retrievals.
• Generated lidar ratio profiles consistent with water phase cloud models.

Conclusions:

• Raman-elastic lidar is a viable tool for daytime measurement of low-altitude optically thin clouds.
• Aerosol correction using combined lidar returns substantially enhances optical depth retrieval accuracy.
• Lidar ratio variability analysis offers insights into cloud droplet distribution near cloud edges.