Absorption and scattering of 106 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 microm). The imaginary part of the refractive index of sea salt inferred from low-power absorption measurements is 200x 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 (CuSO(4).5H(2)O) with an absorption coefficient alpha > or = 0.19 cm(-1) and a dwell time of 100 ms results in a consistent reduction in scattering from the aerosol column. The high-power 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 microm and should result in reduced heating and thermal blooming in open ocean atmospheres.