The Blagopoluchiya Bay is located on the northeast coast of the Novaya Zemlya archipelago (75.63 N, 63.65 E). In the Blagopoluchiya Bay, long-term optical measurements are carried out at the base stations. Measurements discussed in this work were performed during the cruise 89-2 of the R/V Akademik Mstislav Keldysh (AMK), which took place from September 24 to 26, 2022. At this time, which can be attributed to the late autumn season, freshwater runoff, had essentially ceased. Usually this runoff significantly influences the bay's water structure, however during AMK 89-2 the bay was predominantly filled with adjacent waters, and the surface layer was composed of a freshwater lens that approached the eastern coast of Novaya Zemlya.
This comparative study discusses the concentration and major phase composition of suspended particulate matter (SPM) derived from observations collected in the White, Barents and Kara seas in 2001–2021. A selective synthesis is based on our field data on SPM concentrations obtained from water samples and optical data determined from beam attenuation coefficient and light scattering revealed a pronounced difference of seawater optical properties of the western Arctic shelf of Eurasia. The heterogeneous origin of SPM in the studied Arctic seas largely determines different particle size distribution (PSD) and major phase composition of particulate matter in this region. This impacts the optical properties of the water column and hence primary production and sedimentation processes on the western Eurasian Arctic shelf. In recent decades, the dramatic changes in the Arctic climate system, including sea ice, affecting the concentration and composition of SPM as well as optical properties of sea water on the Barents Sea shelf becomes close to ice-free and seasonally ice-free shelves of the White and Kara seas. A pronounced benthic nepheloid layer (BNL) was reveled widespread in the studied seas but it has different thickness and SPM concentration. SPM distribution in the euphotic zone of the seas is much differs due to mostly various catchment-derived material, including river discharge (particulate and dissolved), and other natural geographical conditions. It is necessary to develop regional and seasonal algorithms linking in situ data with remote sensing of bio-optical characteristics of sea water of the Eurasian Arctic shelf.
The spectral light absorption coefficient by phytoplankton pigments, non-algal particles and colored dissolved organic matter were compared in optically contrasting waters of different trophic status. Contribution of optically active components to the total light absorption at 440 nm, as well as the effect of non-water total light absorption on water transparency, were evaluated.
The paper presents a joint analysis of direct measurements of bio-optical, hydro-optical and hydrodynamic characteristics performed on a section through the Lomonosov equatorial undercurrent in December 2019 along 26 degrees of west longitude. The vertical structure of the temperature and salinity of seawater, the speed and direction of the currents, the concentration of chlorophyll-a and the fluorescence of dissolved organic matter (DOM), and light beam attenuation coefficient at 525 and 625 nm were analyzed. The obtained sections show a low content of the main optically active components of seawater. The maximum values of all the analyzed optical parameters were recorded on a pycnocline at depths of 60-80 meters, where phytoplankton cells develop, which mainly determine the variability of the optical characteristics of the region.
The work is devoted to the study of the effect of phycoerythrin pigment on the seawater optical properties in the Atlantic sector of the Southern Ocean. The investigation was carried out in the 79th expedition of the R / V “Akademik Mstislav Keldysh” in January 2020. At some stations, a high content of phycoerythrin was registered in the fluorescence spectra of seawater, the light absorption spectra by suspended particles, and in the remote sensed reflectance spectra of seawater. In particular, the fluorescence of this pigment induced by solar radiation was recorded in ocean color data. The presence of phycoerythrin can lead to uncertainties of the chlorophyll-a concentration estimates from satellite data retrieved with standard algorithms.
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