Water depth extraction of ICESat-2 and application to bathymetric inversion
Compared to traditional bathymetric technologies,satellite-derived bathymetry(SDB)combining ICESat-2 Lidar data and passive optical remote sensing imagery offers advantages such as low cost,wide coverage,no geographical restrictions,and no need for in-situ measurements.In this study,John Brewer Reef in the central part of the Great Barrier Reef(GBF)and Fitzroy Reef in the southern were selected as study areas to carry out bathymetric inversion.To address the low signal-to-noise ratio(SNR)of ICESat-2 photon groups and the difficulty in extracting and correcting water depth for every photon point,we propose an algorithm based on the Gaussian distribution characteristic to extract photons on the sea surface and an algorithm based on depth-adaptive Density-Based Spatial Clustering of Applications with Noise(DBSCAN)to extract photons on the seafloor.Furthermore,we improved the geometric model of refraction correction proposed by Parrish to account for the shift of the incident angle caused by the inclination of the sea level.Our results show that our proposed methods can efficiently and accurately extract effective photon point groups on the sea surface and seafloor.After refraction correction based on the improved model,we found a strong linear relationship between correction and water depth before correction,with a coefficient of about-0.2550.To obtain the sample set required by bathymetric inversion,the optimal cloud-free Sentinel-2 remote sensing image after preprocessing such as atmospheric correction,deglint process,and spatial filtering is spatially matched with the extracted and corrected ICESat-2 water depths.We then use several different models including single band(SB),band ratio(BR),Lyzenga polynomial(LP),quadratic polynomial(QP),cubic polynomial(CP),support vector regression(SVR),multilayer perceptron(MLP),and random forest regression(RF),to invert underwater topography in the study area.By comparing and analyzing the performance of various bathymetric inversion models under different geographical conditions and ICESat-2 sample distribution,this study provides a scientific reference for the strategy of bathymetric inversion with active-passive fusion in different scenarios.
ICESat-2Sentinel-2Extraction of photon point groupRefraction correctionBathymetric inversion
万方数据
维普
