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Fig. 1. Sample volume scattering functions [VSF, β(θ), where θ is the scattering angle] at the small angles and the corresponding log-normal fits. The scattering angle is expressed in degrees rather than in radians (used by Agrawal 2005) to confrom to a more widely used VSF display convention.
The blue diamonds (♦) denote the data of Petzold 1972 (station 7 in clear ocean water off the Bahama Islands, at 530 nm) for the scattering angle range of θ = 0.1° through 80°. The blue curve (—) fitted to these data is described by the following equation: lnβ = a0 + a1 lnθ + a2 (lnθ)2, where a0 = 2.2146 (0.0598), a1 = -1.7594 (0.0202), and a2 = -0.0853 (0.0082), where single SD values are given in the parentheses. According to Petzold, this VSF in angular ranges of 0° to 1° and 0° to 10° degrees contributes respectively ~36% and ~70% to the scattering coefficient.
The red diamonds (♦) denote the data calculated from the phase function data (phf06) of Lee et al 2003 obtained during LEO-15 experiment off the New Jersey (USA) Atlantic coast, wavelength 550 nm. The red curve (—) represents the log-normal fit to these data [a0 = 6.5880 (0.0256), a1 = -1.5748 (0.0256), and a2 = -0.1560 (0.0063)].
The green diamonds (♦) represent unpublished data referred to by Agrawal YC 2005 (courtesy of Y. C. Agrawal) for station 313, depth of ~6 m, summer 2001, also measured in coastal waters off New Jersey, USA. The scattering angle values are those in-water. The green curve (—) is the log-normal fit to these data [a0 = 4.2890 (0.0520), a1 = -1.0689 (0.0225), and a2 = -0.1457 (0.0160)].
The single-component (single-mode) log-normal approximation, as well as other simple functional approximations to the VSF data are unlikely to adequately represent such data in a large range of the scattering angle for waters dominated by a quasi-monosized species of particles as represented by unpublished data of Reynolds RA and Stramski D (gray diamonds ♦, Monterey Bay, CA, USA, depth of 3 m, autumn 2006, dominated in its size range by dinoflagellate A. sanguinea, approximate mean cell diameter of 50 µm, see the data file for additional info). However, a multi-mode log-normal approximation is capable of representing such data much better (Fig. 2).
| CITATION: Jonasz M., Boss E. 2006. Volume scattering function at the small angles (www.tpdsci.com/Tpc/VsfSmlAngNatDsp.php). In: Top. Part. Disp. Sci. (www.tpdsci.com). |
HISTORY: Published: 07-Sep-2006 Modified: 29-Nov-2007 Reviewed: 29-Nov-2007 |
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