Concurrent Particle and Optical Measurements in Western Sargasso Sea
Abstract
Concurrent water samples and optical profiles were taken at twelve stations in the Western Sargasso Sea. Optical measurements included up- and downwelling scalar and vector irradiance. In situ relative fluorescence and beam transmission at 660 nm revealed a particle layer the center of which varied between 70 and 110 m and had a breadth of 20 to 40 m. Water samples were collected within the particle layer and near surface and analyzed for particle characterization and volume absorption. Absorption coefficients for the near surface and particle layer were calculated using three techniques. One method utilized scalar and vector irradiances and calculated absorption as the product of the average cosine and the diffuse attenuation coefficient for net irradiance at wavelengths of 441 and 520 nm. The second method used inversion of the irradiance quartet (up- and downwelling vector and scalar irradiances) and also calculation of absorption from only up- and downwelling vector irradiances. In the third method, absorption coefficients were calculated as the sum of particulate, dissolved substances, and molecule water absorption. Some large discrepancies were found between absorption from apparent properties and those calculated from the component sum. Possible sources of error include overestimation of dissolved substance or particulate absorption, inaccurate pure water absorption, and influence of internal radiance sources, such as Raman scattering, on apparent optical properties. Reprints.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1988
- Accession Number
- ADA201158
Entities
People
- Alan Dean Weidemann
- Dennis M. Lavoie
- Michael R. Wilcox
- Rudolph Hollman
Organizations
- United States Naval Research Laboratory