Vladimir A. Volkov

Sea Ice Drift Tracking From Sequential SAR Images Using Accelerated-KAZE Features

In this paper, we propose a feature-tracking algorithm for sea ice drift retrieval from a pair of sequential satellite synthetic aperture radar (SAR) images. The method is based on feature tracking comprising feature detection, description, and matching steps. The approach exploits the benefits of nonlinear multiscale image representations using accelerated-KAZE (A-KAZE) features, a method that detects and describes image features in an anisotropic scale space. We evaluated several state-of-the-art feature-based algorithms, including A-KAZE, Scale Invariant Feature Transform (SIFT), and a very fast feature extractor that computes binary descriptors known as Oriented FAST and Rotated BRIEF (ORB) on dual polarized Sentinel-1A C-SAR extra wide swath mode data over the Arctic. The A-KAZE approach outperforms both ORB and SIFT up to an order of magnitude in ice drift. The experimental results showed high relevance of the proposed algorithm for retrieval of ice drift at subkilometre resolution from a pair of SAR images with 100-m pixel size. From this paper, we found that feature tracking using nonlinear scale-spaces is preferable due to its high efficiency against noise with respect to image features compared with other existing feature tracking alternatives that make use of Gaussian or linear scale spaces.

Assessment and input to risk management

This chapter presents an assessment of the risk of radiological impact on humans as a consequence of the potential release of radioactive material. Although it is clearly beyond the scope of this chapter to provide a comprehensive risk assessment of all potential environmental and human impacts from all scenarios of radioactive releases in Arctic marine and terrestrial realms, we are able to focus on one major set of risks. These are risks to humans associated with potential releases along the major Siberian rivers—the Ob′ and Yenesei—including an assessment of how global warming may affect the consequences. Section 6.1 is an introduction to the assessment, while various scenarios are described in Section 6.2. Section 6.3 describes how dose models are formulated and implemented. The results of risk assessment modeling are provided in Section 6.4. Section 6.5 presents a summary and major conclusions.

Generic model system (GMS) for simulation of radioactive spread in the aquatic environment

This chapter presents a set of numerical modeling techniques for simulating the spread of radioactivity in the aquatic environment, in both marine and inland waters. Section 3.1 describes the concept and structure of the modeling system. Section 3.2 presents a model for the Atlantic and Arctic Oceans. Section 3.3 presents a shelf sea model for the Kara Sea. Section 3.4 describes in detail the river and estuary models for the Ob′ and Yenisei Rivers. These comprise a one-dimensional model for simulation of the transport of radionuclides in a river system (RIVTOX), and a numerical model for three-dimensional dispersion simulation of radionuclides in stratified water bodies (THREETOX). For each model, we present results from validation of the models against comparable measurement data and knowledge based on observations.

Studies of potential radioactive spread in the Nordic Seas and Arctic using the generic model system (GMS)

This chapter is dedicated to study of the spread of radioactivity in the Arctic using the generic model system (GMS) described in Chapter 3. Two sets of numerical experiments were carried out: (1) simulations or “hindcasts” of past contamination by anthropogenic radionuclides, originating from nuclear bomb testing, atmospheric fallout from Chernobyl, discharges from the Sellafield Reprocessing Plant, and radionuclide transport by river from nuclear plants; (2) simulations of contamination as a result of potential accidents in nuclear plants and submarines.

Sources of anthropogenic pollution in the Nordic Seas and Arctic

This chapter describes the sources of radioactive and non-radioactive contamination in the Arctic and Nordic Seas. The primary and secondary sources of radioactivity in the study region are enumerated and described in Section 1.1. Section 1.2 focuses on a detailed description of three major Russian nuclear industries: (1) the Mayak Production Association, Chelyabinsk; (2) the Siberian Chemical Combine, Tomsk-7; and (3) the Mining and Chemical Combine, Krasnoyarsk-26. Section 1.3 provides a substantial description of non-radioactive pollution, including its sources and spread in the marine environment of the Barents, White, Kara, and Laptev Seas. The descriptions given here have been prepared from information from a range of open-literature material, including a wealth of Russian material and more widely known publications; for example, Arctic Monitoring and Assessment Program (AMAP) reports. An effort has been made to provide the most recent information, although the ever-changing status of pollution sources challenges an evaluation of the present situation.

Study region and environmental datasets

This chapter describes the geography of the study region and the observational environmental data used in these analyses. The geographical and oceanographic features of the study region are described in Section 2.1, which is organized in three sub-sections: the Ob′ and Yenisei River systems, the Kara Sea region, and the Nordic Seas and adjacent seas. Section 2.2 presents an overview of the environmental data that are used in this study, organized in three sub-sections: databases and the information system, natural environmental data (e.g., hydrological, oceanographic, and geophysical), and pollution data.

Studies of the spread of non-radioactive pollutants in the Arctic using the generic model system (GMS)

The Arctic Ocean is threatened with contamination not only from the spread of radionuclides (Chapters 1, 3, and 4) but also by other toxic pollutants—for example, persistent organic pollutants (POPs), petroleum hydrocarbons, and heavy metals (AMAP, 2004, 2009)—see also the latter sections in Chapter 1. Although the levels of many POPs have recently declined in the Arctic environment (AMAP, 2009), “legacy” POPs contaminate the Arctic largely as a result of past use and emissions, and emerging and current-use POPs have the potential to transport to and accumulate in the Arctic. Significant increases in oil exploration on Arctic shelf seas and its transportation are foreseen for the near future (AMAP, 2007). These activities will lead to increased risks of oil contamination of the cold Arctic environment, including ice-covered waters.

Developments Toward a Risk Management Tool for Simulations of Marine Transport of Radioactivity in the Oceans — a Case Study from the Kara Sea

The Arctic particularly the Kara and Barents Seas, has been heavily exposed to radioactivity, due to the fallout from the nuclear testing activities mainly on the Novaya Zemlya during the 1950s and 60s. However, the current level of radioactive contamination in these areas are relatively low as compared to other European waters. The typical levels of radioactive Caesium in the Kara Sea for the period 1987–1994 are in the order of 6 Becquerel/m3 whereas the levels in the Baltic, Kattegatt and North Sea are respectively about 20, 8 and 3 times higher [Anon., 1994].