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Bathymetry — hydrographic surveys and seafloor mapping

Find NOAA hydrographic surveys, bathymetric attributed grids (BAGs), and elevation models for a coastal region.

What this teaches

  • The BATHYMETRY collection (NCEI surveys + Office of Coastal Survey)
  • Pairing with DIGITALCOAST for lidar / DEM coverage
  • Reading the _DR_pdf and _bag asset keys (Descriptive Report and BAG files)

Sources used: BATHYMETRY, DIGITALCOAST

Prompt

Find NOAA hydrographic surveys covering the Florida Keys with download
links to the bathymetric grids.

Transcript

1. Scope to the Keys

search_datasets(
  collections = "BATHYMETRY",
  bbox = "-83,24,-80,25.5",
  limit = 5
)

Real top hits:

Survey ID Title Platform Date
W00424 Straits of Florida — Alligator Reef to Sand Key, FL NOAA Ship Nancy Foster 2011-09-14
W00406 Coastal Florida 16 NM SW of Marquesas Keys NOAA Ship Nancy Foster 2015-06-07
W00397 Dry Tortugas — Tortugas Bank NOAA Ship Nancy Foster 2008-08-09

Each survey is one STAC item. Asset keys include landing-page (NCEI catalog page like https://www.ngdc.noaa.gov/nos/W00001-W02000/W00424.html), <id>_DR_pdf (Descriptive Report), <id>_DR_xml (DR metadata), Download_<id>_xml (full survey package), and one or more <id>_MB_<resolution>_MLLW_<n>of<m>_bag files (Bathymetric Attributed Grids at multiple resolutions, typically 1 m / 2 m / 4 m / 8 m / 16 m).

2. Get a survey's full asset list

get_item(collection = "BATHYMETRY", item_id = "W00406")

Returns landing page, Descriptive Report PDF, all BAG resolutions, and survey metadata XML.

3. Pair with Digital Coast for topo+lidar

search_datasets(
  collections = "DIGITALCOAST",
  bbox = "-83,24,-80,25.5",
  q = "lidar",
  limit = 5
)

Digital Coast covers the topo / shoreline side — DEMs, lidar point clouds, ortho imagery, land cover.

Result the agent gave

"26 hydrographic surveys cover the Florida Keys bbox in the BATHYMETRY collection. The three most relevant from a limit=5 sample:

  • W00424 (Sep 14, 2011 — Straits of Florida, Alligator Reef to Sand Key) — three BAG resolutions: 4 m, 8 m, 16 m. Survey platform: NOAA Ship Nancy Foster. Includes acoustic backscatter (per the keywords).
  • W00406 (Jun 7, 2015 — Coastal Florida, 16 NM SW of Marquesas Keys) — four BAG resolutions: 2 m, 4 m, 8 m, 16 m. Broader bbox covering more of the lower Keys / Tortugas region. Same survey platform.
  • W00397 (Aug 9, 2008 — Dry Tortugas Tortugas Bank) — five BAGs at 1 m, 2 m, 8 m resolutions. Same survey platform.

Each survey delivers BAG files (Bathymetric Attributed Grid, the standard exchange format) at multiple resolutions, plus a Descriptive Report PDF.

For shallow-water topobathy, also pull DIGITALCOAST lidar — better for the shoreline / dry-land side."

Variations

  • Different region: New England (-70,40,-67,43), Pacific NW (-125,46,-122,49).
  • Latest surveys only: sort by -properties.datetime.
  • Resolution filter: filter on the description for specific resolutions, or look at the asset_keys to confirm a 1 m or 2 m BAG is included.