статья в журнале

En

Physical Oceanography

ISSN:1573160

2022

10.22449/1573-160X-2022-5-480-490

Purpose. The paper is aimed at presenting and discussing the results of measurements of the light volume scattering functions and their parameters, and also the suspension composition calculated from the light volume scattering functions in the upwelling zone at the equator in the western Indian Ocean. Methods and Results. The measurement data of the light volume scattering function and the Secchi disk depth were obtained in the 10th cruise of the R/V Akademik Vernadsky in February, 1975. In the equator region, an oceanographic section was carried out along 54.5ºE from 2ºS up to 2ºN with the stations located in each 0.5º. The section data showed a water rise in this region. The following light scattering function parameters were calculated: the scattering and asymmetry coefficients, and the light volume scattering function elongation. Based on the light volume scattering functions, the following suspension parameters were calculated: mass and numerical concentrations of the organic and mineral particles, and average size of the organic particles. At the upwelling maximum at 0.4ºS, the scattering coefficient σ was 0.849 1/m, in the background waters at 2ºN – 0.207 1/m. Increase in the asymmetry coefficient of the light volume scattering function with the scattering coefficient is determined by relation K = 255σ + 6 (R = 0.97). The parameters of the light volume scattering functions and the suspension composition in the upwelling zones at the equator in the Indian and Atlantic oceans were compared; the results showed a higher concentration of small (mineral) suspended particles in the waters of the Atlantic Ocean. At the upwelling maximum, the mass concentration of total suspension Ctotal constituted 0.938 mg/l, and in the background waters – 0.364 mg/l. Conclusions. The common value of angle θmax for the Indian and Atlantic oceans is found to be 3.5º. The obtained relationship between the particle size of organic suspension and the suspension concentration in the upwelling zone confirms the previous studies, namely, productivity increase is accompanied by decrease of the particle sizes, and vice versa, in the low-productivity waters, the particle sizes increase. The bulk of the mass suspension concentration at the section consists of organic particles. © V. I. Mankovsky, 2022.

asymmetry coefficient, mineral suspension, organic suspension, particle size, scattering coefficient, scattering function, white disk

2022-11-09 11:00:29