Abstract
Increased sophistication of high spatial resolution multispectral satellite sensors provides enhanced bathymetric mapping capability. However, the enhancements are counter-acted by per-pixel variability in sunglint, atmospheric path length and directional effects. This case-study highlights retrieval errors from images acquired at non-optimal geometrical combinations. The effects of variations in the environmental noise on water surface reflectance and the accuracy of environmental variable retrievals were quantified. Two WorldView-2 satellite images were acquired, within one minute of each other, with Image 1 placed in a near-optimal sun-sensor geometric configuration and Image 2 placed close to the specular point of the Bidirectional Reflectance Distribution Function (BRDF). Image 2 had higher total environmental noise due to increased surface glint and higher atmospheric path-scattering. Generally, depths were under-estimated from Image 2, compared to Image 1. A partial improvement in retrieval error after glint correction of Image 2 resulted in an increase of the maximum depth to which accurate depth estimations were returned. This case-study indicates that critical analysis of individual images, accounting for the entire sun elevation and azimuth and satellite sensor pointing and geometry as well as anticipated wave height and direction, is required to ensure an image is fit for purpose for aquatic data analysis.
Highlights
Satellite-derived bathymetry (SDB) using optical satellite data has been increasingly implemented as an alternative to traditional bathymetric surveying techniques
Acoustic surveying methods are difficult to conduct in shallow coastal waters because their coverage is limited to where a vessel can safely navigate
Increased sophistication of high spatial resolution multispectral satellite sensors and their ability to point the sensor in multiple off-nadir directions, provides enhanced bathymetric and benthic mapping capability
Summary
Satellite-derived bathymetry (SDB) using optical satellite data has been increasingly implemented as an alternative to traditional bathymetric surveying techniques. Acoustic surveying methods are difficult to conduct in shallow coastal waters because their coverage is limited to where a vessel can safely navigate. Coastal areas often have high population density, heavy maritime traffic and vulnerable ecosystems, such as salt marshes, mangroves, lagoons, and coral reefs. Due to erosion and sedimentation processes, as well as potential changes in sea level, many coastal regions need periodic bathymetry updates. SDB offers a practical means of regularly mapping and monitoring these environments, where the substratum reflectance contains a measureable spectral response compared to that of an optically deep water column, at local and continental scales [1].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
