Assessment of surface oil pollution risks of the southeastern Black Sea based on long-term satellite data

Abstract

In this paper, we discuss applications of satellite remote sensing for detection and analysis of spatiotemporal characteristics of oil showings on the sea surface due to natural hydrocarbon seafloor seeps in deep waters of the southeastern Black Sea. The study is based on the data obtained in the course of a satellite survey of the study region. The study region includes two areas of the heaviest oil pollution of the Black Sea surface. These are the areas of natural seepages off the Georgian coast near the town of Poti as well as the shelf area off the eastern coast of Turkey near the town of Rize. Our main result is the discovery of significant seasonal variability in the spatial distribution of natural oil films affected by local winds and surface currents prevailing in given periods. Further, we show that meso- and sub-mesoscale processes significantly affect the drift of natural oil spills. In the case of moderate winds and weak currents, the influence of these processes on the oil spills drift becomes paramount. We found that in 10-15 percent of cases, the oil film gets involved in vortical motions after its emersion on the sea surface, which often radically changes the trajectory of the slick propagation. Risks of oil surface pollution due to natural hydrocarbon showing are assessed for the test areas.