Alaska Bathymetry, Sediments, and Smooth Sheets
(Click image for 3-D simulation.) Bathymetric surface of Aleutian Islands compiled from National Ocean Service hydrographic surveys and supplemented with some non-hydrographic surveys.
Bathymetry of the Aleutian Islands
AFSC scientists with the RACE Groundfish Program corrected, digitized, and assembled 2.1 million National Ocean Service (NOS) bathymetric soundings from 290 hydrographic surveys represented by smooth sheets, extending 1,900 km along the Aleutian Islands from Unimak Island in the east to the Russian border in the west. The original, uncorrected smooth sheet bathymetry data sets are available from the National Geophysical Data Center (NGDC), which archives and distributes data that were originally collected by the NOS and others. Details of our processing methods can be found in Smooth Sheet Bathymetry of the Aleutian Islands, NOAA Tech Memo NMFS-AFSC-250.
||Map of National Ocean Service verbal sediment descriptions.
Sediments of the Aleutian Islands
We also digitized 25,000 verbal surficial sediment descriptions from 234 of the smooth sheets, providing the largest single source of sediment information for the Aleutian Islands.
Data Available for Download (NOTE: Data are not to be used for navigation).
Users of the data should cite it as
Zimmermann, M., M. M. Prescott, and C. N. Rooper. 2013. Smooth Sheet Bathymetry of the Aleutian Islands. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-250, 43p.
Guide for Working with Alaskan Smooth Sheets
What are Smooth Sheets?
Physically, a paper smooth sheet with muslin backing was the final product of a hydrographic survey. The soundings were drawn on a smooth sheet, along with the shoreline, geographic features (e.g., kelp beds, rocky reefs, islets, rocks), seafloor substrates (e.g., gravel, sand, mud), and the navigational signals in order to provide a visual record of the hydrographic survey, which could be annotated as new information became available.
Though more detailed than navigational charts, smooth sheets are not intended for use in navigation. Instead the smooth sheets, many dating back to the 1930s, were used as internal documents by the hydrographic agency. Only after they were scanned, digitized, and posted to NGDC (Wong et al. 2007) did they become widely used by non-hydrographers. The NOS navigational charts (not smooth sheets) are the legal standard for safe navigation on the ocean (Title 33 Code of Federal Regulations 164).
All scientists who conduct research on the ocean have probably used the small-scale navigational charts for a variety of cruise planning and data analysis tasks without knowing that perhaps ten times as much information was available from the precursor hydrographic surveys, represented by the smooth sheets. Others who are aware of the smooth sheet resource might not understand some of the details about successfully using this rich data resource. Therefore, now that electronic copies of the smooth sheets are readily available, it is worthwhile for non-hydrographers to understand how to use them.
The guide "Smooth sheets: How to work with them in a GIS to derive bathymetry, features and substrates" is intended to provide the user with enough information to understand and properly utlize the smooth sheets and their associated data. The guide should be cited as: Zimmermann, M. and J. Benson. 2013. Smooth sheets: How to work with them in a GIS to derive bathymetry, features and substrates. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-249, 52p.