An Analysis of Bathymetric Sounding Density to Inform Ocean Mapping Strategies

Beginning in May 2017, a team from NOAA and the University of New Hampshire Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM/JHC) conducted a bathymetry gap analysis of the data holdings at International Hydrographic Organization's Data Centre for Digital Bathymetry, which is hosted by NOAA's National Centers for Environmental Information (NCEI). The goals of this ongoing project were to determine and compute the areas "mapped" within U.S. waters and to provide a visual representation of the "mapped" areas to support the planning of an integrated ocean and coastal mapping campaign to fill the gaps by 2030. All modern depth soundings (1960 or later) in U.S. waters and adjacent continental shelf were associated with a 100-m resolution local grid. In 2018, crowdsourced bathymetry, a new and expanding data offering at NCEI, was incorporated into the analysis. This analysis results in a series of 100-m resolution sounding density grids that are viewable via a geospatial web service, published using Esri ArcGIS Enterprise software. The service can be utilized in a desktop GIS as well as in web mapping applications, such as the U.S. Federal Mapping Coordination website, which is sponsored by the U.S. Integrated Working Group on Ocean and Coastal Mapping and the 3D Elevation Program. To account for different definitions of "mapped," this visual product depicts the number of measurements associated with a particular 100-m grid cell as two categories—1 to 2 soundings per cell and 3 or more soundings per cell. The area mapped within U.S. exclusive economic zones and coastal waters can also be estimated. Early computations indicate that approximately 35% of U.S. waters have been mapped to "modern standards," i.e., with 3 or more soundings per 100-m cell. With a target percentage to map and a visualization product to guide the discussion, the opportunity to begin mapping and/or sharing existing data holdings in a strategic manner is apparent.