USGS finds new way to measure ocean depth using Landsat

The most famous researcher to explore this possibility was Jacques Cousteau, who in 1975, along with his team of divers, worked with government agencies and universities to conduct an elaborate test to see if Landsat 1 and 2 could determine the depth of clear, shallow waters. (They could.)

Now, scientists at the U.S. Geological Survey’s Earth Resources Observation and Science (EROS) Center are investigating techniques to improve the availability and accuracy of data from satellites such as Landsat for estimating water depth in near-shore areas. New research has found a fast and effective method that doesn’t even require calibration or separate verification of the accuracy of satellite sensors.

Earth Atmosphere Observing Satellite Scientists Use ‘Novel’ Method to Calculate Depth

To help the international initiative Seabed 2030 map the world’s ocean floor, U.S. Geological Survey geographer Jeff Danielson led a team of researchers from the University of California, Berkeley, and the University of California Davis School of Public Health. USGS Coastal National Elevation Database (CoNED) Application Project Researchers from EROS worked with Curt Storlazzi, a coastal modeler at the U.S. Geological Survey’s Pacific Coastal and Marine Science Center. Their proposal to the Office of Naval Research led to a study of techniques to use satellite imagery to map the water depth, or bathymetry, of selected coral reef areas. One promising approach, led by EROS contractor Minsu Kim, used Landsat data from the Florida Keys, Puerto Rico and Guam.

Danielson calls this approach Recent Research Publications“quite novel.” The algorithm is physics-based, meaning it calculates water depth by simulating sunlight reaching the seafloor and returning to a satellite sensor (in this case, Landsat). There are a lot of physical calculations involved to ensure accurate measurements, taking into account the additional radiation detected by atmospheric particles and reflections of the sky on the water surface, differences in reflectivity from sandy or grassy seafloors, and other factors.

Kim and another EROS contractor, Seonkyung Park, developed software that can quickly perform the technique on satellite imagery that contains three to five visible bands, or wavelength ranges, such as blue, green and red. These bands are included in the most common types of satellite sensors, such as the Landsat Land Imager (OLI), which was used for this study.

“This method and this paper really demonstrate the potential power of Landsat for bathymetry,” Kim said.

“Landsat’s optics and photodetector technology are state-of-the-art,” he added. “It’s one of the best sensors in terms of the optical quality of the radiation. That’s why we were able to demonstrate its capabilities in the water.”