Absorption and scattering of 1.06 μm laser radiation from oceanic aerosols

The absorption and scattering of oceanic aerosols are characterized using low- and high-power lasers in the near IR (1.064 mu m). The imaginary part of the refractive index of sea salt inferred from low- power absorption measurements is 200 x less than the commonly accepted value from the literature. The measured absorption coefficients of natural and artificial saltwater are within 5% of the absorption of pure water (0.14 cm(-1)). High-power aerosol experiments are consistent with low- power liquid absorption measurements, which yield comparable absorption coefficients for pure water and saltwater. High-power illumination of test aerosols (CuSO4 center dot 5H(2)O) with an absorption coefficient alpha >= 0.19 cm(-1) and a dwell time of 100 ms results in a consistent reduction in scattering from the aerosol column. The high-powemr laser scattering measurements are in good agreement with the theory, which accounts for the absorption, heating, and vaporization of the water-based aerosols. The measured absorption of oceanic aerosols in the laboratory is much less than the literature values at 1.064 mu m and should result in reduced heating and thermal blooming in open ocean atmospheres. (C) 2009 Optical Society of America