Gade M, Alpers W
Institut für Meereskunde, Universität Hamburg, Germany.
Sci Total Environ. 1999 Sep 30;237-238:441-8. doi: 10.1016/s0048-9697(99)00156-4.
More than 660 synthetic aperture radar (SAR) images acquired over the southern Baltic Sea, the North Sea, and the Gulf of Lion in the Mediterranean Sea by the Second European Remote Sensing Satellite (ERS-2) have been analyzed since December 1996 with respect to radar signatures of marine pollution and other phenomena causing similar signatures. First results of our analysis reveal that the seas are most polluted along the main shipping routes. The sizes of the detected oil spills vary between < 0.1 km2 and > 56 km2. SAR images acquired during descending (morning) and ascending (evening) satellite passes show different percentages of oil pollution, because most of this pollution occurs during night time and is still visible on the SAR images acquired in the morning time. Moreover, we found a higher amount of oil spills on SAR images acquired during summer (April-September) than on SAR images acquired during winter (October-March). We attribute this finding to the higher mean wind speed encountered in all three test areas during winter. By using an ERS-2 SAR image of the North Sea test area we show how the reduction of the normalized radar backscattering cross section (NRCS) by an oil spill depends on wind speed.
自1996年12月以来，我们对第二颗欧洲遥感卫星（ERS - 2）在地中海的波罗的海南部、北海和利翁湾获取的660多幅合成孔径雷达（SAR）图像进行了分析，以研究海洋污染及其他产生类似雷达特征现象的雷达特征。我们的分析初步结果显示，这些海域在主要航道沿线污染最为严重。检测到的石油泄漏面积在<0.1平方公里至>56平方公里之间。卫星下行（上午）和上行（傍晚）轨道获取的SAR图像显示出不同比例的石油污染情况，这是因为大部分污染发生在夜间，且在上午获取的SAR图像上仍清晰可见。此外，我们发现夏季（4月至9月）获取的SAR图像上的石油泄漏量比冬季（10月至3月）获取的SAR图像上的更多。我们将这一发现归因于冬季在所有三个测试区域遇到的平均风速更高。通过使用北海测试区域的一幅ERS - 2 SAR图像，我们展示了石油泄漏导致的归一化雷达后向散射截面（NRCS）的降低如何随风速变化。
