In situ evaluation of a ship's shadow

Christian T. Weir; David A. Siegel; Anthony F. Michaels; Dave W. Menzies

doi:10.1117/12.190130

26 October 1994 In-situ evaluation of a ship's shadow

Christian T. Weir, David A. Siegel, Anthony F. Michaels, Dave W. Menzies

Proceedings Volume 2258, Ocean Optics XII; (1994) https://doi.org/10.1117/12.190130
Event: Ocean Optics XII, 1994, Bergen, Norway

Abstract

In situ measurements of optical properties made from a ship can be biased by the ship's shadow. In an effort to evaluate the ship shadow perturbation created by the R/V Weatherbird II, profiles of downwelling irradiance, E_d(z,(lambda) ), upwelling radiance, L_u(z,(lambda) ), as well as derived apparent optical properties (AOPs) were obtained at distances of 1, 3, 6 and >= 20 m off the ship's stern. Two statistical analyses are explored here. The first compares the mean difference between simultaneously obtained fluxes and AOPs sampled at distances greater than 20 m from the ship to those taken 1 and 6 m off the stern. The second analysis compares derived AOPs taken at each of the four distances throughout the length of the experiment. Only rarely are significant differences found for data beyond three meters off the ship's stern; however at 1 m off the stern significant discrepancies are intermittently observed. This work illustrates that the inherent sources of noise in determining fluxes and AOPs in the upper ocean are generally greater than the effects incurred by the ship's own shadow under optimal conditions.

Citation Download Citation

Christian T. Weir, David A. Siegel, Anthony F. Michaels, and Dave W. Menzies "In-situ evaluation of a ship's shadow", Proc. SPIE 2258, Ocean Optics XII, (26 October 1994); https://doi.org/10.1117/12.190130

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