Aerosol typing and integral aerosol properties retrieval from Raman lidar data using principle component analysis

In this paper profiles of integral properties of the aerosol size distributions are derived from tropospheric multi-wavelength Raman lidar aerosol extinction and backscatter data using an adapted form of the Principle Component Analysis (PCA) technique. The refractive index of general tropospheric aerosols is variable and aerosol types can vary within one profile. Therefore, any inversion technique applied in the troposphere should account for varying aerosol refractive index. Using PCA, if a set of appropriate refractive index dependent kernels are used, no a priori information about the aerosol type is necessary for the inversion. In principle, some information about the refractive index itself can be retrieved, but this is more sensitive to measurement errors than the various integral properties of the aerosol size distribution.
Here, the PCA technique adapted for use in the troposphere is introduced, the refractive index information content of the kernel sets is investigated and error analyses are presented. The technique is then applied to a real case of tropospheric Raman lidar measurements.