Microphysical particle parameters from extinction and backscatter lidar data by inversion with regularization: experiment

We present effective radius, volume, surface-area, and number concentration s as well as mean complex refractive index of tropospheric particle size di stributions based on lidar measurements at six wavelengths. The parameters are derived by means of an inversion algorithm that has been specifically d esigned for the inversion of available optical data sets. The data were tak en on 20 June and on 20 July 1997 during the Aerosol Characterization Exper iment ACE 2 (North Atlantic/Portugal) and on 9 August 1998 during the Linde nberg Aerosol Characterization Experiment LACE 98 (Lindenberg/Germany). Mea surements on 20 June 1997 were taken in a clean-marine boundary layer, and a large value of 0.64 pm for the effective radius, a low value of 1.45 for the real part, and a negligible imaginary part of the complex refractive in dex were found. The single-scatter albedo was 0.98 at 532 nn. It was derive d from the particle parameters with Mie-scattering calculations. In contras t, the particles were less than 0.2 mu m in effective radius in a continent al-polluted aerosol layer on 20 July 1997. The real part of the complex ref ractive index was similar to 1.6; the imaginary part showed values near 0.0 3i. The single-scatter albedo was 0.84. On 9 August 1998 an elevated partic le layer located from 3000 to 6000 m was observed, which had originated fro m an area of biomass burning in northwestern Canada. Here the effective rad ius was similar to 0.24 mu m, the real part of the complex refractive index was above 1.6, the imaginary part was similar to 0.04i, and the single-sca tter albedo was 0.81. Excellent agreement has been found with results based on sunphotometer and in situ measurements that were performed during the h eld campaigns. (C) 2000 Optical Society of America.