Transit Mapping

Seeking Contributors

This section is under development. If you have expertise in transit mapping, please reach out to the admins at omcadmin@ccom.unh.edu to become a contributor today!

Overview

Vessels in transit routinely cross unmapped (or poorly mapped) regions of the planet. Transits offer important opportunities to map the gaps and verify sonar performance prior to science missions.

Whenever possible, it is helpful to run the mapping systems and collect data for these purposes. Details of the processing and archiving can be addressed after acquisition, if they have not been considered yet, but none of this is possible without the raw data!

This section provides resources for collecting high-quality transit mapping data with limited personnel or experience on board.

Purposes

There are several reasons to collect transit mapping data:

1. Contribute to the global grids, especially in areas without modern multibeam data
2. Verify sonar performance through opportunistic testing with minimal impact on science mission scheduling
3. Build experience with a vessel's specific mapping systems (and their effects on each other) in a low-risk environment
4. Opportunistically document changes in seafloor that may have occured

Typical constraints during transits include:

1. limited availability (or over-scheduling) of marine technicians and experienced multibeam operators
2. limited route planning control for scientific objectives between ports

Resources

The resources below are intended to address the challenges of transit mapping identified above, with the goal of providing high-quality bathymetry that can be incorporated into the global grids.

Global grids

For broader data searches, see Finding existing data

[NEEDS ATTN] For streamlined compilations for the presence or absence of modern multibeam data, consider the following resources:

1. GEBCO data products
2. GMRT mask coverage

Route planning

GeoMapApp

GeoMapApp is a freely available geospatial data discovery and visualization application that offers access to a variety of data layers. The default basemap in GeoMapApp is the Global Multi-Resolution Topography (GMRT). In order to help support gap filling, GeoMapApp makes the GMRT mask layer available and also offers 2 additional coverage layers that show the geospatial extent of known bathymetry data. These layers are sourced from GEBCO, based on its most recent release, and the holdings of the IHO Data Center for Digital Bathymetry which includes the US multibeam archive. These layers can be found under the DataLayers menu under Bathymetry and Land Topography. With these layers turned on, one can rapidly identify unmapped portions of the ocean.

Route planning functionality is offered as a tool entitled "Waypoints and Survey Planner" which can be found under the Portals menu. This feature allows the user to click within the map interface to define a route and/or create parallel survey lines at a set distance apart. The resulting waypoints can subsequently be exported for use in a variety of other software packages.

GEBCO

Gap Filler

Data acquisition

Vessel speed

Considerations for mapping data quality vs. vessel speed based on RX noise testing, sea state, and scheduling

Sonar operation

Optimizing sonar settings when round-the-clock watchstanding is not possible

Avoiding the most common pitfalls of transit mapping

Sound speed

Setting expectations for acquiring sound speed profiles when needed and relying on atlas data when necessary. Sound speed corrections can be performed in post-processing and concerns about inadequate monitoring of sound speed during acquisition should not deter opportunistic mapping opportunities during transits.

Considering the relatively low cost and high impact of sound speed profiles on data quality

Underway processing

Basic checks for data quality

Frequent and simple checks to catch data quality issues as soon as possible

Automated processing

Let the computer do the work!

Qimera

Caris

Daily products

Quick and easy processing to show daily progress and check sonar performance

Post-transit steps

Processing

Minimal data quality standards for contributing to the global grids, and resources to achieve or exceed these. GMRT Tools are especially well suited for processing transit data because it enables the comparison of data with underlying QA/QC'd data.

Data submission

Any transit data acquired aboard US Academic Research Vessels will be delivered to the NOAA/NCEI archive through the R2R Program. Once data are made publicly available, they will be processed by one (or many) groups interested in integrating the data. Once data are processed, it is recommended that processed data are shared in GSF (Generic Sonar Format) files which will enable additional processing and/or corrections if necessary.