Zoffoli Maria Laura, Frouin Robert, Kampel Milton
Remote Sensing Division, National Institute for Space Research (INPE), Av. dos Astronautas 1758, São José dos Campos, SP 12227-010, Brazil.
Scripps Institution of Oceanography, UCSD, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Sensors (Basel). 2014 Sep 11;14(9):16881-931. doi: 10.3390/s140916881.
Human activity and natural climate trends constitute a major threat to coral reefs worldwide. Models predict a significant reduction in reef spatial extension together with a decline in biodiversity in the relatively near future. In this context, monitoring programs to detect changes in reef ecosystems are essential. In recent years, coral reef mapping using remote sensing data has benefited from instruments with better resolution and computational advances in storage and processing capabilities. However, the water column represents an additional complexity when extracting information from submerged substrates by remote sensing that demands a correction of its effect. In this article, the basic concepts of bottom substrate remote sensing and water column interference are presented. A compendium of methodologies developed to reduce water column effects in coral ecosystems studied by remote sensing that include their salient features, advantages and drawbacks is provided. Finally, algorithms to retrieve the bottom reflectance are applied to simulated data and actual remote sensing imagery and their performance is compared. The available methods are not able to completely eliminate the water column effect, but they can minimize its influence. Choosing the best method depends on the marine environment, available input data and desired outcome or scientific application.
人类活动和自然气候趋势对全球珊瑚礁构成了重大威胁。模型预测，在不久的将来，珊瑚礁的空间范围将大幅缩减，生物多样性也会下降。在这种情况下，监测珊瑚礁生态系统变化的项目至关重要。近年来，利用遥感数据绘制珊瑚礁地图受益于分辨率更高的仪器以及存储和处理能力方面的计算进步。然而，当通过遥感从水下基质中提取信息时，水柱会带来额外的复杂性，这就需要校正其影响。本文介绍了底部基质遥感和水柱干扰的基本概念。提供了为减少遥感研究的珊瑚生态系统中水柱影响而开发的方法概要，包括其显著特点、优点和缺点。最后，将用于反演底部反射率的算法应用于模拟数据和实际遥感影像，并比较了它们的性能。现有的方法无法完全消除水柱效应，但可以将其影响降至最低。选择最佳方法取决于海洋环境、可用的输入数据以及期望的结果或科学应用。
