Spectral Skylight and Solar Radiance Measurements in the Caribbean: Maritime Aerosols and Sahara Dust

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  • 1 Air Force Cambridge Research Laboratories, Bedford, Mass.
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Abstract

Measurements of solar radiation from λ0.45 to 1.6 μm during May 1969 at St. Croix (Virgin Islands) in the western tropical Atlantic showed a minimum of aerosol optical thickness near 0.6 μm, which is probably typical of a maritime aerosol. From 5–15 July, measurements at Puerto Rico showed highly variable and generally neutral aerosol attenuation in this wavelength range. Moreover, the skylight scattering function did not seem to be typical of either a maritime or continental aerosol. During this period, transport of Sahara dust to the Caribbean was observed in satellite photographs and from BOMEX aircraft, and large amounts of mineral dust were measured at Barbados. There is evidence that our observations also show this dust.

Abstract

Measurements of solar radiation from λ0.45 to 1.6 μm during May 1969 at St. Croix (Virgin Islands) in the western tropical Atlantic showed a minimum of aerosol optical thickness near 0.6 μm, which is probably typical of a maritime aerosol. From 5–15 July, measurements at Puerto Rico showed highly variable and generally neutral aerosol attenuation in this wavelength range. Moreover, the skylight scattering function did not seem to be typical of either a maritime or continental aerosol. During this period, transport of Sahara dust to the Caribbean was observed in satellite photographs and from BOMEX aircraft, and large amounts of mineral dust were measured at Barbados. There is evidence that our observations also show this dust.

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