Edward M. Sweeney 2004 remote-sensing image http://www.ngdc.noaa.gov/mgg/coastal/model.html http://pubs.usgs.gov/of/2004/1082/arcgis/coastal_relief/farallones_crm.zip E.M. Sweeney W.W. Danforth T. F. O'Brien H.A. Karl W.C. Schwab 2004 Open-File Report 2004-1082 Woods Hole Science Center, Woods Hole, MA U.S. Geological Survey, Coastal and Marine Geology Program http://pubs.usgs.gov/of/2004/1082 The National Grids that integrate land and seafloor elevations are needed by planners using LIS/GIS software to manage the US coastal zone, which encompasses the coastal states out to the country's 200-mile offshore limit. Geophysical Data Center (NGDC) is addressing this need by assembling a gridded database that merges the US Geological Survey 3-arc-second DEMs with a vast compilation of hydrographic soundings collected by the National Ocean Service and various academic institutions. The principal component of the database is 3-arc-second elevation grids, of areas 1 degree in longitude by 1 degree in latitude, in which elevations are resolved to 1/10 of a meter. The database also includes grids containing the number of soundings enclosed by each cell in the offshore areas of the elevation grids, and images of both the elevation and sounding density grids. The latter are in common graphic formats that can be displayed by a range of UNIX-based and personal computer software. The TIFF image generated from the Coastal Relief Model provides a basemap for Geographic Information System (GIS) database. 2001 publication date Complete None planned -124.027552 -121.971435 39.005471 36.995780 General USGS U.S. Geological Survey Coastal Relief Model CRM bathymetry Geographic Information Systems CMGP Coastal and Marine Geology Program GIS field activity identifier F9-89-NC field activity serial number 89020 Woods Hole Science Center General Farallones Gulf of the Farallones California U.S. West Coast U.S. Central Pacific Coast North America Pacific Ocean United States Half Moon Bay Point Reyes Farallon Islands Bodega Bay San Francisco None Public domain data from the U.S. government is freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of this dataset. Edward M. Sweeney U.S. Geological Survey Research Assistant mailing and physical address

384 Woods Hole Rd.

Woods Hole MA 02543 USA (508) 548-8700 x2307 (508) 457-2310 esweeney@usgs.gov Microsoft Windows 2000 Version 5.1 (Build 2600) Service Pack 1; ESRI ArcCatalog 8.3.0.800 Soundings for each volume of the Coastal Relief model series are compiled from hydrographic surveys conducted by the National Ocean Service (NOS) and from various academic institutions. The surveys were carried out using a variety of sounding methods including SeaBeam 16-beam, 12-kHz swath mapping system (6000- >3000m operating water depths), General Instruments 17-beam, 36-kHz Hydrochart II swath mapping system (5-150m operating water depths), single-beam echosounder (e.g., 3.5 kHz narrow 2 degree beam), and lead-line sounding method. These latter surveys date as far back as the late 1800's. A wide range of navigation methods are also associated with the surveys. Visual navigation is based on three-point sextant fixes, theodolite intersections, and celestial fixes. Electronic navigation involves short to long range positioning systems that run the gamut from Loran-C (0.25 - 5 nm accuracy) to differential GPS ( 1 m accuracy). Despite the varying sounding and navigation techniques upon which they are based, all of the NOS soundings used in constructing the Coastal Relief Model meet rigorous standards for accuracy. The same standards are employed by the International Hydrographic Office and have remained relatively consistent since the 1800's. The vertical accuracy of the soundings The horizontal accuracy of the soundings is generally 30 m, but it can vary from as fine as 15 m in ports and estuaries to as coarse as 75 m in the offshore areas. Differential GPS has improved this level of accuracy considerably for the most recent survey data. Land elevations within the gridded dataset come from the United States Geological Survey/ National Image Mapping Agency (USGS/NIMA) 1:250,000 or 1 degree DEMs of the states. A description of the USGS/NIMA DEMs and how they were derived can be accessed on the World Wide Web at http://edcwww.cr.usgs.gov/glis/hyper/guide/1_dgr_dem. Our focus, however, is on the bathymetric soundings that are used in constructing the offshore regions of the grids. Soundings for each volume of the Coastal Relief model series are compiled from hydrographic surveys conducted by the National Ocean Service (NOS) and from various academic institutions. The surveys were carried out using a variety of sounding methods including SeaBeam 16-beam, 12-kHz swath mapping system (6000- >3000m operating water depths), General Instruments 17-beam, 36-kHz Hydrochart II swath mapping system (5-150m operating water depths), single-beam echosounder (e.g., 3.5 kHz narrow 2 degree beam), and lead-line sounding method. These latter surveys date as far back as the late 1800's. A wide range of navigation methods are also associated with the surveys. Visual navigation is based on three-point sextant fixes, theodolite intersections, and celestial fixes. Electronic navigation involves short to long range positioning systems that run the gamut from Loran-C (0.25 - 5 nm accuracy) to differential GPS ( 1 m accuracy). Despite the varying sounding and navigation techniques upon which they are based, all of the NOS soundings used in constructing the Coastal Relief Model meet rigorous standards for accuracy. The same standards are employed by the International Hydrographic Office and have remained relatively consistent since the 1800's. The vertical accuracy of the soundings is 0.3 m in 0 - 20 m of water, 1.0 m in 20 - 100 m of water, and 1% of the water depth in 100 m of water. The horizontal accuracy of the soundings is within a radius of 1.5 mm of the sounding location at the scale at which the soundings are recorded. NOS surveys are plotted at map scales that range from 1/10,000 for harbors and channels to 1/50,000 for open ocean surveys, with 1/20,000 being the most commonly used scale. The horizontal accuracy of the soundings is generally 30 m, but it can vary from as fine as 15 m in ports and estuaries to as coarse as 75 m in the offshore areas. Differential GPS has improved this level of accuracy considerably for the most recent survey data. While the NOS soundings collected since 1965 have been recorded digitally, those collected prior to this time were recorded manually and then used to make hand-drawn bathymetric maps. Approximately 1,550 of these hand-drawn bathymetric maps have been digitized and assimilated into the NOS Hydrographic Database and, subsequently, were used in constructing the many volumes of the gridded dataset. These data are complete (see: http://www.ngdc.noaa.gov/mgg/coastal/model.html) The horizontal accuracy of the soundings is generally 30 m, but it can vary from as fine as 15 m in ports and estuaries to as coarse as 75 m in the offshore areas. The vertical accuracy of the soundings is 0.3 m in 0 - 20 m of water, 1.0 m in 20 - 100 m of water, and 1% of the water depth in 100 m of water. National Oceanic and Atmospheric Administration 2001 CD-ROM 2001 publication date NGDC Coastal Relief Model, U.S. Central Pacific Coast, vol. 7 Vol 7 was used to create the TIFF image of the Gulf of the Farallones coastal relief The desired Coastal Relief Model data was extracted from volume 7 in ESRI ASCII format, and then converted to an ESRI grid. Using the ArcMap Spatial Analysis extension, a hillshade was then created from the ESRI grid file (Azimuth:30; Altitude:45; z-factor:1). After creating a desirable color scheme, the ESRI grid file and hillshade were combined using the ArcView extension grid-to-image converter tool (downloaded from www.esri.com) to create a TIFF image file and world file. 2004 Edward M. Sweeney U.S. Geological Survey Research Assistant mailing and physical address

384 Woods Hole Rd.

Woods Hole MA 02543 USA (508) 548-8700 x2307 (508) 457-2310 esweeney@usgs.gov Raster Pixel 2687 2150 1 Universal Transverse Mercator 10 0.999600 -123.000000 0.000000 500000.000000 0.000000 row and column 82.810425 82.810425 meters D_WGS_1984 WGS_1984 6378137.000000 298.257224 The Coastal Relief Model TIFF image of the Gulf of Farallones is a shaded relief image. A shaded relief image is produced by applying an artificial light source to elevation (topographic or bathymetric) data. The azimuth, elevation, and vertical exaggeration are specified. The light source produces shadows within the imagery, as if the sun were shinning upon the region. Applying an artificial light source to elevation data, yields an image that is more easily interpreted by the end-user. Nancy Soderberg U.S. Geological Survey Data Librarian mailing and physical address

384 Woods Hole Rd.

Woods Hole MA 02543 USA (508) 548-8700 x2275 (580)457-2313 nsoderberg@usgs.gov Farallones_CRM.tif Although this data set and its lineage have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data or its related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related items. Users must assume responsibility for the proper use of these data. The data should not be used at resolutions for which they are not intended. The data have not been reviewed for conformity with U.S. Geological Survey editorial standards, or the North American Strigraphic code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government. 20040419 Edward M. Sweeney U.S. Geological Survey Research Assistant mailing and physical address

384 Woods Hole Rd.

Woods Hole MA 02543 USA (508) 548-8700 x2307 (508) 457-2310 esweeney@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time