The paper discusses our studies of oil pollution in the Black and Caspian Seas. The research was based on a multi-sensor approach on satellite survey data. A combined analysis of oil film signatures in satellite synthetic aperture radar (SAR) and optical imagery was performed. Maps of oil spills detected in satellite imagery of the whole aquatic area of the Black Sea and the Middle and the Southern Caspian Sea are created. Areas of the heaviest pollution are outlined. It is shown that the main types of sea surface oil pollution are ship discharges and natural marine hydrocarbon seepages. For each type of pollution and each sea, regions of regular pollution occurrence were determined, polluted areas were estimated, and specific manifestation features were revealed. Long-term observations demonstrate that in recent years, illegal wastewater discharges into the Black Sea have become very common, which raises serious environmental issues. Manifestations of seabed hydrocarbon seepages were also detected in the Black Sea, primarily in its eastern part. The patterns of surface oil pollution of the Caspian Sea differ considerably from those observed in the Black Sea. They are largely determined by presence of big seabed oil and gas deposits. The dependence of surface oil SAR signatures on wind/wave conditions is discussed. The impact of dynamic and circulation processes on oil films drift and spread is investigated. A large amount of the data available allowed us to make some generalizations and obtain statistically significant results on spatial and temporal variability of various surface film manifestations.The examples and numerical data we provide on ship spills and seabed seepages reflect the influence of the pollution on the sea environment.

The paper discusses the results of a study of short-period internal waves (IWs) in the Black and Caspian Seas from their surface manifestations in satellite imagery. Since tides are negligible in these seas, they can be considered non-tidal. Consequently, the main generation mechanism of IWs in the ocean—interaction of barotropic tides with bathymetry—is irrelevant. A statistically significant survey of IW occurrences in various regions of the two seas is presented. Detailed maps of spatial distribution of surface manifestations of internal waves (SMIWs) are compiled. Factors facilitating generation of IWs are determined, and a comprehensive discussion of IW generation mechanisms is presented. In the eastern and western coastal zones of the Black Sea, where large rivers disembogue, intrusions of fresh water create hydrological fronts that are able to generate IWs. At the continental shelf edge, on the west and northwest of the Black Sea and near the Crimean Peninsula, IWs are generated primarily due to relaxation of coastal upwelling and inertial oscillations associated with hydrological fronts. In addition, IWs can be formed at sea fronts associated with the passage of cold eddies. In the Caspian Sea, seiches are the main source of the observed IWs.

In this paper the remote sensing satellite sensor data (obtained by Envisat Advanced Synthetic Aperture Radar (ASAR), Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS), and National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) instruments) is used to study coastal dynamics of the north-eastern Black Sea. Occurrence, evolution and drift of small-scale eddies in coastal waters are investigated. Seasonal variability of their manifestations is established. Instances of surface manifestations of non-tidal internal waves (IW) are discovered. The main finding was that practically all cases of IW manifestations were observed in the vicinity of mesoscale sea eddy structures or hydrological fronts. The joint analysis of data from different sensors was performed to reveal specific conditions leading to the intensification of wave processes and to their manifestation in radar imagery as well as to determine possible sources of the IW generation.

A new approach aimed at a better understanding of the state of pollution of the Black Sea coastal zone is suggested. It consists of the combined use of all available quasi‐concurrent satellite information (NOAA AVHRR, TOPEX/Poseidon, Jason‐1, Terra/Aqua MODIS, Envisat ASAR, ERS‐2 SAR and QuikSCAT) and was first applied during an operational seawater monitoring campaign in the coastal zone of the northeastern Black Sea conducted in 2006. The monitoring is based on daily receiving, processing and analysis of data different in nature (microwave radar images, optical and infrared data), resolution and surface coverage. These data allow us to retrieve information on seawater pollution, sea surface and air–sea boundary layer conditions, seawater temperature and suspended matter distributions, chlorophyll‐a concentration, mesoscale water dynamics, near‐surface wind, and surface wave fields. Such an approach helps in oil spill detection with synthetic aperture radar (SAR), especially in distinguishing oil slicks from look‐alikes. The focus is on coastal seawater circulation mechanisms and their impact on the evolution of pollutants.

This paper presents the results of a long-term survey of the Caspian Sea using satellite SAR and multispectral sensors. The primary environmental problem of the Caspian Sea is oil pollution which is determined by its natural properties, mainly by the presence of big oil and gas deposits beneath the seabed. Our research focuses on natural oil slicks (NOS), i.e., oil showings on the sea surface due to natural hydrocarbon emission from seabed seeps. The spatial and temporal variability of NOS in the Caspian Sea and the possibilities of their reliable detection using satellite data are examined. NOS frequency and detectability in satellite images depending on sensor type, season and geographical region are assessed. It is shown that both parameters vary significantly, and largely depend on sensor type and season, with season being most pronounced in visible (VIS) data. The locations of two offshore seep sites at the Iranian and Turkmenian shelves are accurately estimated. Statistics on individual sizes of NOS are drawn. The release rates of crude oil from the seabed to the sea surface are compared. Detailed maps of NOS are put together, and areas exposed to high risk of sea surface oil pollution are determined.