Improved method for retrieving the aerosol optical properties without the numerical derivative for Raman–Mie lidar

• We propose a retrieval method without derivative calculation for Raman–Mie lidar.
• Errors of traditional method caused by the numerical derivative can be reduced.
• The tests demonstrate that the improved method is more accurate and robust.

Raman–Mie light detection and ranging (lidar) is a very useful tool for research on atmospheric aerosol optical properties with high spatial–temporal resolution. However, many uncertainties still exist in data retrieval because traditional retrieval methods need to calculate the numerical derivative for aerosol extinction coefficient (AEC), which may cause large errors, particularly with low signal-to-noise ratios. Thus, we present an improved method for retrieving aerosol optical properties. We re-formulate the N2-Raman lidar equation to obtain an unknown term which contains the AEC at the Mie wavelength. We replace the unknown term of the equation in traditional method for retrieving aerosol backscatter coefficient (ABC). Then, AEC can be retrieved by the accurate ABC and Mie lidar signal without calculating the numerical derivative. Tests on the simulated and measured signals show that results of our method and those of the traditional method have similar tendencies. However, our method is more accurate and robust, and the significant errors of AEC caused by the numerical derivative can be reduced.