Office of Coast Survey
National Oceanic and Atmospheric Administration
U.S. Department of Commerce
What is BlueTopo™?
BlueTopo is a compilation of the nation's best available bathymetric data. In the same way that topographic map details the height of land, BlueTopo details the depth of lake beds and seafloor beneath navigationally significant U.S. waters. Created as part of the Office of Coast Survey nautical charting mission and its National Bathymetric Source project, BlueTopo is curated bathymetric source data to provide a definitive nationwide model of the seafloor and the Great Lakes.
NOAA's Office of Coast Survey is the nation's nautical charting authority in U.S. waters. Nautical charts are maps that provide professional mariners and recreational boaters with the information they need to navigate safely, such as water depths, locations of hazards, and other features.
Historically, depth information on nautical charts has been drawn from many different, often sparse, bathymetric sources that can be difficult to access and update. The National Bathymetric Source project is part of a new Office of Coast Survey workflow to modernize the charting process and to provide a critical bathymetry resource to several customers, including the public. For example, NBS supports Precision Navigation by providing seamless, high-resolution bathymetric data to better equip mariners in making critical navigation decisions. BlueTopo is the public "not for navigation" compilation of bathymetry produced by the Office of Coast Survey.
Though the Office of Coast Survey's primary goal is to support marine navigation, bathymetric data is essential to virtually all forms of ocean science and engineering. BlueTopo will help to enhance the growth of the Blue Economy by aiding in the selection of alternative energy sites and identifying geologic features and hazards. Further, BlueTopo will support coastal resilience by enabling simulations of sea level effects on coastal ecosystems, helping to identify sensitive marine habitats. BlueTopo will provide critical bathymetric data for new NOS' operational numerical oceanographic forecast modeling systems. These real-time modeling systems provide short-term forecast guidance of water levels, currents, water temperature, and salinity to mariners. As a publicly available resource, BlueTopo enables a more complete understanding of bathymetry in numerous applications.
What constitutes the best available bathymetry?
Bathymetry is measured through various survey methods that yield different levels of accuracy and precision. BlueTopo is the result of compiling the highest quality data. The International Hydrographic Organization defines quality of bathymetric data according to measurement uncertainty, feature detection capability, coverage, survey age, and changeability of the location. Generally, bathymetric source data is of the highest quality when there is low horizontal and vertical uncertainty, high resolution, and was acquired recently using the latest surveying techniques.
Primary sources of bathymetry in NBS compilations include NOAA and U.S. Army Corps of Engineers hydrographic surveys and topographic bathymetric (topo-bathy) lidar (light detection and ranging) data. Data submitted through the NOAA Office of Coast Survey's external source data process are also included. Contact firstname.lastname@example.org for more information about how to submit bathymetry data. Coverage gaps in water greater than 200 meters are filled in BlueTopo through Global Multi-Resolution Topography, a merged model of bathymetry made available through Lamont-Doherty Earth Observatory.
Rapid advances in technology have improved data quality significantly over a short time, but many areas around the U.S. haven't been surveyed in over 100 years, and in some cases haven't been surveyed at all. In addition to compiled bathymetry, BlueTopo also contains the metadata with quality metrics from the source data to enable appropriate use of the product. For general questions or feedback about the data, please submit inquiries through the NOAA Office of Coast Survey ASSIST Tool.
How is BlueTopo unique?
BlueTopo is unique in its delivery of consistently formatted bathymetry, transparency of metadata, and method of compilation according to data quality metrics. The design and implementation of the National Bathymetric Source project and BlueTopo also involves the intentional use of open source software and code to ensure flexibility.
Though other compilations of bathymetry exist, BlueTopo is the first of its kind that will account for changes in data quality over time. As new data becomes available, BlueTopo will be updated on a weekly to monthly basis, according to regional rates of coastal change and availability of new source data.
How do I access BlueTopo
We look forward to hearing from you! Let us know how you are using BlueTopo and how it has impacted your work. Please visit the FAQs prior to contacting us with questions the NOAA Office of Coast Survey ASSIST Tool.