Oil Spill (or oil spillage) on the water surface is a discharge of mineral oil into a body of water, such as from offshore drilling rigs, oil tankers, or underwater oil pipelines.

After entering the water, oil (or oil products) typically forms a thin film on the water surface, which is called an oil slick, marine surface slick, or oil sheen. Oil spills can also be present as a thick layer on the water surface in the form of oil-in-water emulsions, which rarely sink to the seabed.

Oil spill detection can spread both horizontally across the water surface and vertically within the water column. Wind and surface water currents are the primary factors responsible for the spread of oil across the water surface. The impact of an oil spill on the environment depends on factors such as the speed and direction of the oil movement, its location relative to human habitats and marine species, and the type and extent of its surface coverage in the ocean.

Monitoring oil spills and oil products(oil spill detection) in water bodies using satellite imaging is a crucial tool for quickly detecting and identifying the sources and locations of oil spills in closed water bodies and marine environments. This information helps in making decisions about effective measures for containment and cleanup.

The contamination of water bodies with oil products is caused by both "human factors" (such as tanker collisions and/or shipwrecks) and natural disasters (hurricanes, landslides, earthquakes), as well as accidents involving offshore drilling rigs or underwater oil pipelines.

Advancements in remote sensing technology have contributed to some extent in detecting oil spills. However, the presence of elements (doppelgangers) in images with similar visual characteristics hinders the quick detection and timely decision-making to respond to emergencies.

Accurate modeling of the trajectory of oil slicks remains a challenging task.

Optical and radar images are used for monitoring oil spills, and Synthetic Aperture Radar (SAR) sensors are more widely used globally due to their ability to operate in all weather conditions. However, the accuracy of interpreting optical and radar images for detecting oil spills depends on the presence of biogenic elements, which can lead to false positive detections of oil spills.

Conducting satellite-based environmental monitoring of marine areas (identification of oil contamination) is driven by the need to detect instances of surface pollution with oil products, identify contaminated areas, potential sources of pollution, and likely transport pathways. It also involves assessing the environmental damage caused by oil and oil product leaks.

• Minimize field and marine work.
• Rapidly localize and assess the scale of anthropogenic impact, including oil spills.
• Evaluate the degree of influence of anthropogenic impact, including oil spills, on ecosystems.
• Significantly reduce the overall duration of work due to the coverage and speed of obtaining data. Currently, for example, Synthetic Aperture Radar (SAR) technology is recognized worldwide as the most effective for detecting and mapping oil spills, thanks to its high spatial resolution and all-weather capabilities of current SAR sensors. In any case, due to their current satellite revisit cycles and the presence of a significant number of SAR-equipped satellites in orbit, RS data technologies can be advantageously used for rapid detection and continuous monitoring in near real-time mode.
• Automating the processing of RS (Remote Sensing) data based on new AI algorithms and neural networks in significant water bodies, which is not always feasible with field (marine) methods.

Oil Slick Drift Forecasting requires the use of radar satellite images. Among its advantages are: Independence from cloud cover, fog, and smoke. The microwave radiation used in space radar operates at frequencies of 3.1 cm (X-band) to 23.5 cm (L-band), which possess high penetrating capabilities. Radar imaging is employed, for example, to detect underground communications and other buried structures.

Independence from the time of day (illumination conditions). Radar imaging uses an autonomous source of radiation, allowing obtaining satellite images in the dark. This property, combined with all-weather capabilities, allows for a substantial increase in the amount of extractable information and ensures regular monitoring of the area of interest. Possibility of extracting additional information from satellite images. Besides information about oil contamination, radar images can provide data about the maritime situation at the time of the spill, ice conditions, as well as the extraction of surface wind speed and direction fields at the time of imaging (see figure below), which directly affects the dynamics of the spread of contamination.

Satellite radar monitoring technologies for oil pollution are widely used in many countries as part of emergency response systems. There are several approaches to monitoring water bodies using radar data, but they can be divided into 2 main groups:

APPROACH № 1: OPERATIONAL MONITORING

National operational control systems for oil pollution in coastal waters and territorial waters can serve as an example of the first group, established in Norway, the USA, Canada, and others.

In Norway, the state system for operational control of accidental pollution of territorial waters is organized based on coordinated satellite and aviation monitoring. In an automated mode, the reception, processing, and analysis of radar information are carried out, along with the comparison of detected pollutions with automated identification system (AIS) data of vessels. The identified pollutions are interpreted with a degree of detection reliability (high, medium, low), and the results are transmitted in real-time through web services to the Norwegian Pollution Control Authority (SFT), operating under the Ministry of Environment. The Norwegian Coast Guard dispatches a patrol aircraft to the accident area, and the observations from the aircraft help refine the scale of pollution and determine the responsible party.

In Canada and the USA, a similar system operates as part of the Integrated Satellite Tracking of Oil Pollution (ISTOP) governmental program.

The disadvantages of this approach include relatively high system costs, the possibility of receiving false alarms/missing real spills (due to automated processing focused on immediacy). Additionally, within the framework of operational monitoring, there is usually no provision for modeling the dynamics of pollution spread.

APPROACH № 1: CREATING COMPLEX GIS-MONITORING SYSTEMS

To address this task, as well as collecting spill statistics for forecasting purposes, the methodologies of the second group are aimed at creating comprehensive GIS-monitoring systems.

Within such systems, which are also widespread in European Union countries (CleanSeaNet, PRIMI programs, etc.) and often complement operational monitoring systems, the collection and integration of archival and new radar images with additional sources of information are part of a unified geoinformation system. The goal is to obtain the most comprehensive information about a specific pollution, analyze its source, and forecast/reconstruct the dynamics of its spread.

The presence of an oil spill monitoring (oil spill detection) system using a complex of aerospace methods with a time lag of about 4 hours (as of December 2022) allows for on-site situation control and environmental analysis for the presence of oil and oil product spills in the area of interest n years prior.