Oil spill mapping in the western part of the East China Sea using synthetic aperture radar imagery

Abstract

Oil spills are one of the major environmental concerns, especially in the coastal zones of the ocean. Synthetic aperture radar (SAR) imagery from the European Remote Sensing (ERS)‐2 and Envisat satellites has proved to be a useful tool for monitoring oil spills in the marine environment due to its all‐weather and all‐time capability. More than 600 scenes with SAR images acquired over the western part of the East China Sea in 2002–2005 were collected, and of these, 120 scenes containing pronounced oil spills were processed and analysed. To analyse SAR image signatures of the oil spills, a geographic information system (GIS) framework was used. The oil spills were distinguished from look‐alike phenomena by using other remote sensing data, and contextual information was incorporated into the GIS to obtain an oil spill distribution map for the western part of the East China Seas. Analysis of the temporal and spatial distribution of the oil spills revealed the risk areas and confirmed previous findings that oil spills are mainly distributed along regional shipping routes. This verifies that illegal discharges from ships are the main source of oil pollution in this region. The detailed analysis also revealed different types of oil pollution and showed diurnal and seasonal variations in the amount of oil spills detected by SAR images acquired in the morning/evening time and in the summer/winter.