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摘要
Water flow speeds and directions in Teshekpuk Lake on the Arctic Coastal Plain of northern Alaska were derived from remotely sensed optical images captured after a major storm event. A Landsat 7 Enhanced Thematic Mapper Plus image and a Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer image, acquired about 41min apart on 15 August 2000, were analysed with an image matching technique based on cross-correlation to find corresponding features in both images. Flow speed and direction were calculated by measuring the horizontal displacement of such features in the two images. The derived water current speed ranged from 0.6 to 9.6cm/s (mean 3.0cm/s), during a wind blowing from the SE at an average speed of 4.9m/s. The fastest currents (>2 standard deviations) fringed the shorelines and flowed in the direction of the wind (toward the NW), likely reflecting the direct influence of the wind conditions at the time of image acquisition. In contrast, a 10km-wide gyre rotating clockwise developed towards the centre of the lake, likely reflecting the influence of a storm-driven wind veering over a 7day period prior to the time of image acquisition. This study demonstrates that extensive water velocity fields in a lake can be derived from remotely sensed images using an image matching technique. The different flow patterns would not be readily observable without the synoptic view provided by satellite images, although the accuracy of flow speeds and directions needs further validation.
- 出版日期2017-3
