Identifying Bathymetric Differences over Alaska's North Slope using a Satellite-derived Bathymetry Multi-temporal Approach Journal of Coastal Research

Many nautical charts of Alaska's North Slope are based on chart data that have not been updated since the early 1950s. Additionally, these charts may have been compiled using inadequate data and contain unsurveyed areas. However, with more days per year of diminished Arctic sea-ice coverage, including along the North Slope, marine transportation in this region has increased during the past decade, thus increasing the need for updated nautical charts. Due to limited resources available for U.S. Arctic surveying, the National Oceanic and Atmospheric Administration (NOAA) is evaluating the capabilities of satellite-derived bathymetry (SDB). This technology has proven useful as a reconnaissance tool in tropical and subtropical waters and clear-water conditions, especially over sandy seafloor. But in the Arctic, glacial flour from land reduces water clarity and limits the light penetration depth, which may affect SDB calculations. A new multi-temporal SDB approach is described in this paper using multiple images to extract "clear water" areas acquired on different dates. As a proof-of-concept, the extinction depth and bathymetry were calculated over areas that overlap with NOAA Charts 16081 and 16082 using Landsat 7 and Landsat 8 imagery. The derived and charted bathymetry are similar in most areas up to 4.5 m deep. The results of the study also identified a potential uncharted shoal. The multi-temporal SDB approach was further investigated by NOAA and was used to process imagery for other areas along Alaska's North Slope. As a result, the new editions of NOAA Chart 16081 include the location of a potential uncharted shoal, which is the first time an SDB product was utilized for a NOAA chart. Grant no. NA10NOS4000073