Manifestations of Upwellings in the Black Sea in Multisensor Remote Sensing Data

Abstract

The paper presents the results of a study of upwelling in the Black Sea in three marine areas: in the northeastern part of the sea, near the Tendrovskaya Spit and the Western Crimea, and off the coast of Turkey. They are based on the use of multi-sensor remote sensing data, namely ocean color scanners (MODIS, VIIRS, OLCI-a and OLCI-b), infrared radiometers (TIRS and AVHRR), as well as synthetic aperture radar (SAR) images acquired by spaceborne SARs. An integrated approach using practically only remote sensing data makes it possible to quite fully characterize the observed upwellings in the sea. In the active phase, upwelling, in addition to sea surface temperature (SST), is usually displayed both in the phytoplankton chlorophyll-a concentration (chlor-a) and in the sea surface roughness on the SAR images. In the analyzed cases, the duration of upwellings varied from 6 to 10 days, the SST differences in the upwelling zone were up to 8°С, and the concentrations of chlor-a were 5–6 times higher than the background values of 0.5–0.7 mg/m3. The maximum SST anomalies, which are about 8°C, were observed off the Turkish coast. As a result of the analysis, a dynamic relationship was revealed between the areas of low SST in the upwelling zone (compared to the sea waters surrounding this zone), sea surface roughness and chlor-a concentration. It is shown that in the case of using the full set of available remote sensing data, the observation, monitoring and study of upwelling does not present any fundamental difficulties.