Combining OPAC and lidar

The properties of aerosol particles are highly variable, both in time and space. This refers to the number density, the microphysical properties (size distribution, refractive index, effective radius), and to the height distribution. In most cases the actual properties are not known. Using lidar data together with models can help improve the knowledge regarding the particulate atmospheric constituents which affect local radiative forcing, the radiation balance of the earth, and thus climate. This paper presents an attempt to integrate elastic backscatter lidar data in OPAC software package in order to find the most realistic aerosol vertical distribution and their optical and microphysical characteristics. The necessity to reduce the variability of naturally occurring aerosols to typical cases, but without neglecting possible fluctuations, is achieved in OPAC by the use of a dataset of typical internally mixed aerosol components. In addition, any mixtures of the basic components can be used to calculate the overall optical parameters. Experimental or modeled meteorological profiles (temperature, pressure, relative humidity) in complementary to experimental lidar data are used to calculate the solutions of lidar equation that fits, in an iterative manner, to the output of the model. Two type of uncertainties are diminished in this way: first, the modeled profiles of lidar ratio are used in lidar data processing instead of a constant value; second, aerosol height profiles are no longer being assumed in the model, but directly measured. This procedure was applied to synthetic lidar signals in order to test its advantages and limitation.