Remote Sensing for Risk Analysis of Oil Spills in the Arctic Ocean.
Johansson, Malin; Eriksson, Leif; Hassellöv, Ida-Maja
Chalmers University of Technology, SWEDEN

Predicted decreases in sea-ice extent and shift from multi-year ice to seasonal ice opens up for the possibility to use the Northwest and the Northeast passages as commercial shipping routes within the near time future. The prolonged open water season already means that the number of passages is increasing every year. The growth in shipping is thought to originate from an increased demand for transportation from the Atlantic to the Pacific regions and from an increase in supply and rescue ships for the expanding offshore activities in the Arctic. Using the northern sea routes implies reduced travel distances and consequently they are more cost and time effective. With expected growth in marine shipping in the Arctic region the potential threat of accidents is increasing. It is therefore vital to not only have safety procedures to follow to prevent accidents from happening but also to have good protocols to follow if an accident do happen.

Within this project we aim to provide information about the potential geographical distribution of oil pollution along prospective future shipping lanes in the Arctic (Fig. 1). The project is a part of a larger collaboration where a risk assessment of oil spill in the Arctic is set up, combining the distribution of the oil and the biochemical impact of the spill on the environment. In this part of the project SAR images will be used to provide input data about the changes in the Arctic sea ice cover, including regional shifting from multi©\year ice to seasonal ice, sea-ice concentration and information on the wind patterns over open water at 10 meters height. Combining this data with information about ocean currents we will make estimates on the redistribution and spread of oil pollution scenarios. Different size of oil spills and spills with different type of oil will be included (Fig. 1). Algorithms for retrieval of sea-ice concentration (Berg and Eriksson, 2012) and wind fields (Carvajal et al., 2013) have been implemented and tested and algorithms for sea-ice drift and sea surface currents are currently being developed.

Figure 1. Set up of the data needed for the dispersion part of the risk assessment. Information in blue boxes will be provided using satellite images. Information in green boxes will be provided using information from the shipping scenarios and shipping statistics.

The risk assessment method will initially be set up using historical satellite data. Satellite observations dating back to 1978 will be used to follow the trends of sea-ice within the Arctic Region. These data mainly originate from passive sensors and have the advantage of large spatial coverage and high temporal resolution. Regarding SAR data used in the Arctic region the spatial extent and the need for high temporal resolution has meant that medium spatial resolution such as Envisat ASAR Wide Swath data has been favored when extracting sea-ice information. Hence, at the initial stages the main focus will be on Envisat ASAR Wide Swath data extracted from the ESA rolling archive. The first results are expected during the summer and 2013 and will be presented at the symposium. The risk assessment method will be set up to comply with future satellite missions like Sentinel-1 and ALOS-2.

References: Carvajal G., Eriksson L.E.B., Ulander L., 2013, Retrieval and Quality Assessment of Wind Velocity Vectors on the Ocean with C-band SAR, Submitted to; IEEE Transactions on Geoscience and Remote Sensing
Berg A. and Eriksson L.E.B., 2012, SAR Algorithm for Sea Ice Concentration ¨C Evaluation for the Baltic Sea, , IEEE Geoscience and remote sensing letters, Vol. 9, No. 5, pp. 938-942