Light absorption by black sand dust

Light absorption by fine and coarse aerosols derived from Hawaiian black sa nd was determined by light transmission. The real part of the refractive in dex of this material was measured directly, and the imaginary part was esti mated. The measured light absorption coefficients (B-ap) were adjusted for multiple scattering artifacts by use of absorption-to-extinction ratios est imated with Mie theory. The best agreement between calculated and measured fine and coarse B-ap was achieved with a value of 0.014 for the imaginary p art of the refractive index. The corresponding absorption efficiencies for the fine and coarse black sand aerosols were 0.22 and 0.09 m(2)/g, respecti vely. (C) 2000 Optical Society of America OCIS codes: 010.1110, 010.1120, 0 10.1280, 010.1290.