Swath Bathymetry Surveys of the Monterey Bay Area from Point Año Nuevo to Moss Landing, San Mateo, Santa Cruz, and Monterey Counties, California

A Note on Coordinate Systems

WGS84 and NAD83 have been revised several times resulting in coordinate shifts of up to several meters in X,Y, and Z. The revision is indicated by the designator following the name (G1150 following WGS84, for example). Be very careful using software that does not distinguish between the different versions of these datum; lack of the designator is a warning sign that your software does not support 3D datum properly. Users should pay particular attention to the accompanying metadata files to ensure that the data are properly georeferenced. In particular, note that most current GIS software (including ArcGIS 9.3) cannot properly transform high-resolution elevation data from one 3D datum to another (such as WGS84 G1150 to NAD83 CORS96) without introducing errors on the order of 1 m to 2 m in X,Y, and Z. For this reason, data are provided in both WGS84 G1150 (equivalent to ITRF2000) and NAD83 CORS96 (Equivalent to NSRS2007).

Data Tables

Raw bathymetry

The raw bathymetry dataset is provided in ESRI GRID and ASCII GRID format in WGS84 (G1150), UTM Zone 10 North.

Standard deviation

The standard deviation of the raw bathymetry grid is provided in ESRI ASCII GRID format in WGS84 (G1150), UTM Zone 10 North. This represents the weighted standard deviation for all of the soundings used to compute the elevation of the grid cell.

Interpolated bathymetry DEM

The interpolated bathymetry DEM is provided in ESRI ASCII GRID format in WGS84 (G1150) and NAD83(CORS96), UTM Zone 10 North (vertical datum NAVD88). A full resolution hillshaded image of the data can be viewed with any KML viewer through the following KML link. (.kmz)

Normalized amplitude

The amplitude dataset is provided as a geotiff with a worldfile and in ESRI ASCII GRID format in WGS84 (G1150) and NAD83(CORS96), UTM Zone 10 North. Users should consider the file size when choosing which product to download. Full-resolution backscatter imagery can also be viewed online with any KML viewer through the following link. (.kmz)

Sound Velocity Profiles

Sound velocity profiles are provided in a .kmz file viewable in Marble, Google Earth, Microsoft Virtual Earth, Nasa Worldwind, and other viewers which support the .kml standard. Text files and plot images also are provided in a zipped archive below. These data are ancillary to SWATH mapping and are provided primarily for completeness and archival purposes. A total of 438 sound velocity profiles were taken during this project. Coordinates are provided in WGS84 (G1150), UTM Zone 10 North, and in geographic coordinates. (.kmz)

*Data are provided in WGS84 G1150 and NAD83 CORS96. Please note the coordinate system for the files you download.*
File Name	Format	Reference Frame	Vertical Datum
monterey_bay_DEM_NAD83_utm10_NAVD88.asc.zip (355 Mb) Processed DEM. Elevation values are meters relative to NAVD88 sea level.	ASCII Grid	NAD83 CORS96	NAVD88
monterey_bay_ampl_NAD83_utm10.zip (340 Mb) Gain-normalized backscatter. Higher values are higher-amplitude backscatter	ASCII Grid	NAD83 CORS96	N/A (amplitude)
monterey_bay_ampl_NAD83_utm10.tif.zip (244 Mb) Gain-normalized backscatter. Higher values are higher-amplitude backscatter	GeoTIFF & .tfw file	NAD83 CORS96	N/A (amplitude)
monterey_bay_raw_WGS84_utm10.asc.zip (199 Mb) Raw elevation grid. Elevation values are meters relative to the WGS84 Ellipsoid (ellipsoidal height)	ASCII Grid	WGS84(G1150)	WGS84(G1150)
monterey_bay_DEM_WGS84_utm10.asc.zip (214 Mb) Processed DEM. Elevation values are meters relative to the WGS84 Ellipsoid (ellipsoidal height)	ASCII Grid	WGS84(G1150)	WGS84(G1150)
monterey_bay_STD_WGS84_utm10.asc.zip (201 Mb) Standard deviation (2 sigma). Values are in meters	ASCII Grid	WGS84(G1150)	WGS84(G1150)
monterey_bay_ampl_WGS84_utm10.asc.zip (340 Mb) Gain-normalized backscatter. Higher values are higher-amplitude backscatter	ASCII Grid	WGS84(G1150)	N/A (amplitude)
monterey_bay_ampl_WGS84_utm10.tif.zip (244 Mb) Gain-normalized backscatter. Higher values are higher-amplitude backscatter	GeoTIFF & .tfw file	WGS84(G1150)	N/A (amplitude)
monterey_bay_SVP_data.zip (5.5 Mb) Sound velocity profiles collected during the Monterey Bay SWATH bathymetry survey	.png & txt(svp) files and indices.	WGS84(G1150) & WGS84 geographic	depth relative to sea surface
Notes:
(1) All data are projected into Universal Transverse Mercator (UTM) Zone 10 North.
(2) Each ESRI ASCII Grid file (*asc) in the table is accompanied by FGDC metadata in both text and .xml format. The naming convention is: <name of grid>.txt or <name of grid>.xml, respectively.
(3) All coordinates (northings, eastings, and heights) are in meters.

For more information, contact David Finlayson.