Vol. 39, issue 10, article # 4

Abstract:

In May 2020, anomalously high values of remote sensing reflectance were recorded in the western part of the Black Sea in in situ measurements at the AERONET-OC stations Section‑7_Platform and Galata_Platform. Satellite imagery and in situ atmospheric measurements revealed an intense dust transport event over the Black Sea between May 10 and 17, 2020. The lag between the peak of dust loading (May 15–16) and the onset of the bloom (May 17–23) was 4–5 days. The particulate backscattering coefficient b_bp(555) and its coccolithophore-associated fraction were calculated using regional algorithms. At the bloom peak, b_bp(555) reached 0.026–0.040 m^-1, with the contribution of coccolithophores increasing from 30% to 60–80%. Analysis of alternative factors (river discharge, upwelling, temperature, precipitation, and salinity) showed that none of them could be considered the main cause of the bloom in May 2020. We conclude that Saharan dust deposition was the dominant, if not the only, source of bioavailable phosphorus and iron for the Black Sea surface layer during the observed bloom. The results can be used for improving satellite monitoring and forecasting extreme coccolithophore bloom events under the changing climate.

Keywords:

coccolithophores, Black Sea, mineral dust, bloom, remote sensing reflectance, particulate backscattering coefficient, MODIS Aqua/Terra, AERONET

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