Roberto J. Anima
John L. Chin
David P. Finlayson
Mary L. McGann
Florence L. Wong
2007
4-m resolution bathymetric grid of Tomales Bay, California (TOMALESG)
Version 1.0, September 19, 2007
map
USGS Open-File Report
USGS OFR 2007-xxxx
Menlo Park, California
U.S. Geological Survey
<URL:http://pubs.usgs.gov/of/2008/1237/>
The Tomales Bay bathymetry Digital Elevation
Model (DEM) is composed of data from three
bathymetric surveys collected between November
2004 and August 2006 (USGS activities F-1-04-TB,
F-2-05-TB, B-1-06-TB). During the 2004 and 2005
surveys, the northern and central bay bathymetry
was collected using an interferometric sidescan
system. In 2006, the shoal tidelands in the
southern portion of the bay were surveyed using a
single-beam echo sounder. The final data set
described in this report is a composite of these
three surveys.
This metadata record describes the Tomales Bay grid exported as
1. ESRI ASCII grid format (includes nodata -9999 values)
> ncols 3172
> nrows 3959
> xllcorner 501413.013329
> yllcorner 4216501.279255
> cellsize 4
> NODATA_value -9999
> -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999
> -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999
> -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999
> -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999
> -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999
> -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999
> -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999 -9999
> -9999 -9999 -5.298165 -4.233628 -9999 -9999 -9999
> -9999 -9999 -9999 -9999 -9999 -
2. x-y (decimal degrees) and z (elevations in meters) data (nodata excluded).
> -122.98086,38.23902,-5.298
> -122.98082,38.23902,-4.234
> -122.98090,38.23898,-5.162
> -122.98086,38.23898,-5.997
These data are intended for science researchers, students, policy
makers, and the general public. The data can be
used with geographic information systems (GIS) software
to display geologic and oceanographic information.
Additional information about the field activities from
which this data set was derived are available online at
>http://walrus.wr.usgs.gov/infobank/f/f104tb/html/f-1-04-tb.meta.html
>http://walrus.wr.usgs.gov/infobank/f/f205tb/html/f-2-05-tb.meta.html
>http://walrus.wr.usgs.gov/infobank/b/b106tb/html/b-1-06-tb.meta.html
Any use of trade, product, or firm names is for descriptive purposes
only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata
file is intended to document the data set in nonproprietary form,
as well as in ArcInfo format, this metadata file may include some
ArcInfo-specific terminology.
2006
Ground Condition
None Planned
-122.98388487
-122.83886718
38.23903649
38.09620335
None
coastal geology
bathymetry
sidescan
interferometric sidescan
ISO 19115 Topic Category
environment
geoscientificInformation
oceans
Geographic Names Information System
Tomales Bay, California
Inverness Ridge, California
San Andreas Fault, California
Avalis Beach, California
Lawsens Landing, California
Pelican Point, California
Blakes Landing, California
Marconi, California
Hearts Desire Beach, California
Millerton Point, California
Inverness, California
Lagunitas Creek, California
Toms Point, California
White Gulch, California
Tomales Beach, California
Marshall Beach, California
Lairds Landing, California
Cypress Grove, California
Reynolds, California
California
USA
GEOnet Names Server
north Pacific Ocean
None
These data are not to be used for navigation.
Florence L. Wong
United States Geological Survey (USGS)
Coastal and Marine Geology (CMG)
Geologist, GIS Coordinator
mailing and physical address
USGS, MailStop 999, 345 Middlefield Road
Menlo Park
CA
94025-3561
USA
(650) 329-5327
(650) 329-5190
fwong@usgs.gov
http://pubs.usgs.gov/of/2008/1237/images/tomalesg.jpg
preview image of report
gif or jpg
SunOS, 5.8, sun4u UNIX
ArcInfo version 9.1
The advertised accuracy of the SWATHplus system in shallow
waters is better than IHO S44 Special Order, but a total
propagation error model has not been developed for the USGS
system used in these surveys so the true error in both
position and elevation is unknown. Furthermore, no
operational tide measurements were available for the survey
so there is likely to be a spatially and temporally
variable vertical error due to differences between the
predicted tides and the water levels actually experienced
during the survey. Finally, a comparison of grid elevations
having overlapping coverage between the 2004 and 2005
surveys revealed a 1.44 m vertical offset (median of all
overlapping cells). This error may be due to a
mis-configuration of the F180 unit, but the exact cause of
the error is unknown. In the final DEM, a static offset of
+1.44 m was added to the 2004 data to minimize the vertical
offset between the 2004 and 2005 data. No additional
vertical error analysis has been performed on these data.
Not applicable for raster data.
See Attribute_Accuracy_Report.
See Attribute_Accuracy_Report.
Swath bathymetry.
Swath bathymetry for the northern and central portions of
Tamales Bay (cruise F-1-04-TB and F-2-05-TB) were collected
using a pole-mounted, SEA Inc., 234 kHz, SWATHplus
interferometric sidescan sonar system. Attitude
compensation and vessel positioning were provided by a
CodaOctopus F180 attitude and positioning system. Sound
velocity profile measurements were collected with an
Applied Micro Systems, SvPlus 3472.
The horizontal datum of the surveys was established by
differential GPS using the WGS84 ellipsoid. The vertical
datum of the surveys was based on Mean Lower Low Water
(MLLW) predictions for Marshall, Tomales Bay, using the
software Tides and Currents by Nobeltec.
Raw bathymetry and amplitude data were collected using the
Swath Processor software provided with the sonar system and
gridded at 1 m resolution using the accompanying Grid
Processor software package. These raster data were then
exported to Fledermaus, edited and smoothed in that package
and finally exported to ESRI ASCII Grid format using USGS
in-house software.
2006
Single-Beam Bathymetry.
Single-beam echo sounder data were collected over the
shallow tidelands of southern Tomales Bay during August
2006 (cruise B-1-06-TB). A pole-mounted ESE50 Echo sounder
with a co-located Real-time kinematic (RTK) GPS receiver
system provided real-time vertical and horizontal
positioning of the sonar transducer during operations.
These data were reduced to positional soundings on the sea
floor using HYPACK (version 6.2) with a 30-second averaging
period (to remove heave), gridded into a 10-m resolution
DEM using Surfer version 8.0, and exported to ESRI ASCII
Grid format using USGS in-house software.
The horizontal and vertical datum of the survey was
established by the RTK GPS system as WGS84 and NAVD88,
respectively. The error ellipse on the location of the GPS
receivers is typically < 5 cm and this propagates through
to the sea floor with RMS errors on sea bed elevation of <
10 cm.
2006
4 m composite bathymetry.
Each of the three surveys was resampled to a 4 m cell
spacing using the Spline Smooth tool of Surfer 8. The swath
bathymetry was converted from MLLW to NAVD88 vertical datum
using VDatum (NOAA Office of the Coast Survey and National
Geodetic Survey), and then the three surveys were blended
together in ArcGIS using the MOSAIC TO NEW RASTER tool with
the blend option. The final data set was trimmed to the
convex hull of the survey data area.
2006
First draft of metadata created by florence using
FGDCMETA.AML ver. 1.35 08/02/2000 on ArcInfo data set
/we6/florence/cordell/tomales/covs/tomalesg
20070919
Raster
Grid Cell
3959
3172
Universal Transverse Mercator
10
0.9996
-123.0
0.0
500000
0
coordinate pair
4.0
4.0
Meters
WGS84
WGS84
6378206.4
294.98
>
>TOMALESG.STA:
>
>COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME
> 1 MIN 8 15 F 3
> 9 MAX 8 15 F 3
> 17 MEAN 8 15 F 3
> 25 STDV 8 15 F 3
>
> MIN MAX MEAN STDV
> -19.150 0.668 -4.379 2.452
>
none
United States Geological Survey (USGS)
Coastal and Marine Geology (CMG)
Florence L. Wong
Geologist, GIS Coordinator
mailing and physical address
USGS, MailStop 999, 345 Middlefield Road
Menlo Park
CA
94025-3561
USA
(650) 329-5327
(650) 329-5190
fwong@usgs.gov
USGS OFR 2007-xxx
Please recognize the U.S. Geological Survey (USGS) as the source of
this information.
Although these data have been used by the U.S. Geological Survey,
U.S. Department of the Interior, no warranty expressed or implied
is made by the U.S. Geological Survey as to the accuracy of the
data.
The act of distribution shall not constitute any such warranty,
and no responsibility is assumed by the U.S. Geological Survey in
the use of this data, software, or related materials.
Compressed file including Arcinfo grid and metadata.
9.2
Arcinfo ASCII grid
windows winzip or unix gunzip
5 MB
http://pubs.usgs.gov/of/2008/1237/
none
20070919
200710
United States Geological Survey (USGS)
Coastal and Marine Geology (CMG)
Florence L. Wong
Geologist, GIS Coordinator
mailing and physical address
USGS, MailStop 999, 345 Middlefield Road
Menlo Park
CA
94025-3561
USA
(650) 329-5327
(650) 329-5190
fwong@usgs.gov
FGDC Content Standards for Digital Geospatial Metadata ("CSDGM version 2")
FGDC-STD-001-1998
none
none