Evaluation of UV Aerosol Retrievals from an Ozone Lidar

Abstract. Aerosol retrieval using ozone lidars in the ultraviolet (UV) band is challenging but necessary for correcting aerosol interference in ozone retrieval and for studying the ozone-aerosol correlations. This study describes the aerosol retrieval algorithm for a tropospheric ozone lidar, quantifies the retrieval error budget, and intercompares the aerosol retrieval products at 299 nm with those at 532 nm from a high spectral resolution lidar (HSRL). After the cloud-contaminated data is filtered out, the aerosol backscatter or extinction coefficients at a 30-m and 10-min resolution retrieved by the ozone lidar are highly correlated with the HSRL products, with a coefficient of 0.95 suggesting that the ozone lidar can reliably measure aerosol structures with high spatio-temporal resolution when the signal-to-noise ratio is sufficient. The actual uncertainties of the aerosol retrieval from the ozone lidar generally agree with our theoretical analysis. The backscatter color ratio (backscatter-related exponent of wavelength dependence) linking the coincident data measured by the two instruments at 299 and 532 nm is 1.34 ± 0.11 while the Angstrom (extinction-related) exponent is 1.49 ± 0.16 for a mixture of urban and fire smoke aerosols within the troposphere above Huntsville, AL, USA.