Andrew A. Armstrong

The International Bathymetric Chart of the Arctic Ocean (IBCAO) Version 3.0

The International Bathymetric Chart of the Arctic Ocean (IBCAO) released its first gridded bathymetric compilation in 1999. The IBCAO bathymetric portrayals have since supported a wide range of Arc ...

Mapping supports potential submission to U.N. Law of the Sea

Multibeam bathymetric data from selected U.S. continental margins are being collected for use in the future development of potential submissions that the United States may make to the United Nations Commission on the Law of the Sea (UNCLOS) to extend the nations sovereign rights over the resources of the seafloor and the subsurface. n nHowever, the new data also represent a valuable resource for the next generation of marine geologists to study the complexity of surficial processes of several U.S. continental margins. For example, the details of the morphology of large sediment slides on the U.S.Atlantic continental slope and rise have been mapped, and enigmatic features such as a meandering channel on a channel levee on the U.S.Alaskan Pacific margin have been discovered.

Satellite Remote Sensing as a Reconnaissance Tool for Assessing Nautical Chart Adequacy and Completeness

National hydrographic offices need a better means of assessing the adequacy of existing nautical charts in order to plan and prioritize future hydrographic surveys. The ability to derive bathymetry from multispectral satellite imagery is a topic that has received considerable attention in scientific literature. However, published studies have not addressed the ability of satellite-derived bathymetry to meet specific hydrographic survey requirements. Specifically, the bathymetry needs to be referenced to a chart datum and statistical uncertainty estimates of the bathymetry should be provided. Ideally, the procedure should be based on readily-available, low-cost software, tools, and data. This paper describes the development and testing of a procedure using publicly-available, multispectral satellite imagery to map and portray shallow-water bathymetry in a GIS environment for three study sites: Northeast United States, Nigeria, and Belize. Landsat imagery and published algorithms were used to derive estimates of the bathymetry in shallow waters, and uncertainty of the satellite-derived bathymetry was then assessed using a Monte Carlo method. Results indicate that the practical procedures developed in this study are suitable for use by national hydrographic offices.

So, How Deep Is the Mariana Trench?

HMS Challenger made the first sounding of Challenger Deep in 1875 of 8184 m. Many have since claimed depths deeper than Challengers 8184 m, but few have provided details of how the determination was made. In 2010, the Mariana Trench was mapped with a Kongsberg Maritime EM122 multibeam echosounder and recorded the deepest sounding of 10,984 ± 25 m (95%) at 11.329903°N/142.199305°E. The depth was determined with an update of the HGM uncertainty model combined with the Lomb-Scargle periodogram technique and a modal estimate of depth. Position uncertainty was determined from multiple DGPS receivers and a POS/MV motion sensor.

Depth adaptive hydrographic survey behavior for autonomous surface vessels

When autonomous surface vessels conduct systematic seafloor surveying using a swath sonar system, the fixed angular coverage leads to differing horizontal coverage width with depth. Traditionally, missions have been pre-planned using fixed line spacing accounting for the minimum expected depth or with the intention of leaving gaps in some areas. A path planning algorithm and accompanying behaviors have been developed to adaptively survey a region for complete coverage with minimal gaps. Subsequent paths are planned based on measured depths in the field and this process continues until a defined area is completed or a depth threshold reached. The algorithm has been simulated in a custom environment and integrated into the MOOS-IvP marine autonomy system.