Project

This project demonstrates a method for creating satellite-derived bathymetry (SDB) through fusion of Landsat 8 Operational Land Imager (OLI) and ICESat-2 Advanced Topographic Laser Altimeter System (ATLAS) data. NASA's ICESat-2, which carries a single-photon, green-wavelength (532 nm) lidar, serves as the reference data from which bathymetric digital elevation models (DEMs) can be produced using a ratio between logarithms of blue and green OLI bands. Previous work by the Oregon State University team that inspired this project is described in detail in recent publications in Remote Sensing and Photogrammetric Engineering and Remote Sensing.
This webGIS was developed with support from NASA ROSES Grant #80NSSC20K0964, as well as Grant #G14AP00002 from the Department of the Interior, United States Geological Survey (USGS) to AmericaView.

---

General Workflow

• ICESat-2 data with a bathymetric profile are found then downloaded from Open Altimetry
• Data are extracted within an area of interest surrounding the bathymetric profile
• Water surface and bathymetric bottom are classified in order to obtain depth
• Points receive refraction correction
• Landsat 8 Operational Land Imagery (OLI) with clear view of bathymetric bottom is downloaded from Earth Explorer
• OLI imagery is atmospherically corrected for surface reflectance using ACOLITE downloaded from the Royal Belgian Institute of Natural Sciences
• A linear regression is done between refracted depth values from ICESat-2 data and a ratio of logs raster of two bands from Landsat 8 imagery to determine coefficients
• A final satellite-derived bathymetry (SDB) raster is produced by applying these coefficients to the ratio of logs raster



All data are in UTM, with a vertical datum of EGM2008, and units in meters

---

FAQ

What is with the unusually-shaped holes in the DEMs?

Lingering clouds, shadows, and other obstructions in the input imagery need to be clipped out since bathymetric depths can only be obtained from areas where seafloor is visible. This includes includes areas that are considered "optically deep" (i.e. where the seafloor is not longer visible through the water column). While effort is made to find the best, most cloud-free imagery to run our process on, this is not always the case. Therefore, the problematic areas described have been clipped out from the final DEMs.

Why are there unnatural artifacts in the DEMs?

Continuing with the topic topic above, sometimes it is too difficult/time consuming to clip out ALL areas where bathymetric depth retrieval failed. This includes piers, docks, boats, small clouds, and other features that otherwise obstruct visibility of the seafloor.

---

Disclaimer

The team involved in the production and dissemation of the data on this website do not claim responsibility for improper use of said data. These bathymetric models are intented for research and should not be used for activities that could put body or vessel in harm's way. As mentioned above, these data do not meet International Hydrographic Organization (IHO) hydrographic survey standards, and as such should not be used for nautical navigation.

---

Bathymetric DEMs and website created by:
Ben Babbel (babbelbe@oregonstate.edu)
Special thanks to Richie Slocum and Chris Parrish

---