Testing of the 4SM Method in the Gulf of California Suggests Field Data Are not Needed to Derive Satellite Bathymetry

Abstract

Satellite-derived bathymetry methods over coastal areas were developed to deliver basic and useful bathymetry information. However, the process is not straightforward, the main limitation being the need for field data. The Self-calibrated Spectral Supervised Shallow-water Modeler (4SM) method was tested to obtain coastal bathymetry without the use of any field data. Using Landsat-8 multispectral images from 2013 to 2016, a bathymetric time series was produced. Groundtruthed depths and an alternative method, Stumpf’s Band Ratio Algorithm, were used to verify the results. Retrieved (4SM) vs groundtruthed depths scored an average r2 (0.90), and a low error (RMSE = 1.47 m). 4SM also showed, over the whole time series, the same average accuracy of the control method (40%). Advantages, limitations and operability under complex atmosphere and water column conditions, and high and low-albedo bottom processing capabilities of 4SM are discussed. In conclusion, the findings suggest that 4SM is as accurate as the commonly used Stumpf’s method, the only difference being the independence of 4SM from previous field data, and the potential to deliver bottom spectral characteristics for further modeling. 4SM thus represents a significant advance in coastal remote sensing potential to obtain bathymetry and optical properties of the marine bottom.

Preliminary Assessment of Turbidity and Chlorophyll Impact on Bathymetry Derived from Sentinel-2A and Sentinel-3A Satellites in South Florida

“…Additionally, waters of different turbidity levels scatter the incoming radiation differently, introducing further complexity in highly dynamic coastal regions. There have been a few studies that have developed different methodologies to map water depths accounting for the turbidity signal to some extent [16][17][18][19][20][21]. An analytical retrieval method from hyperspectral data is one example, which compensates for the degradation of accuracy in depth retrievals as the waters become deeper or more turbid [22].…”

Very High-Resolution Satellite-Derived Bathymetry and Habitat Mapping Using Pleiades-1 and ICESat-2

“…Finally, the ratio transform was implemented with the algorithm developed by [23]. A map of the relative water depth (i.e., log ratio of the spectral bands) was derived from the log ratio between the green and blue spectral bands [44][45][46][47][48][49].…”

Analysis of Depths Derived by Airborne Lidar and Satellite Imaging to Support Bathymetric Mapping Efforts with Varying Environmental Conditions: Lower Laguna Madre, Gulf of Mexico

“…Water-leaving radiance is the backscatter upwelling after traversing the air/water interface and recording subsurface volumetric and bottom information. Previous studies developed the bottom albedo-independent bathymetric algorithm that accurately distinguishes bottom types such as sand, rock, and vegetation up to 15 m depth under ideal atmospheric and water conditions [38,39].…”