These data have not been quantitatively compared to previous hydrographic data, although they generally agree with qualitative comparison of published NOAA charts.
Soundings were gridded in OMG SwathEd software using the entire swath width across track to achieve maximum coverage at the scale of the entire Apalachicola Bay/St. George Sound survey area. Although the soundings were manually edited, small data spikes may exist at outer edges of some swaths.
Pockmark features that appear in the dredge channel of the intracoastal waterway fairways are artifacts of the processing methods used to generate a continuous surface from swath bathymetry collected on lines spaced 100m apart.
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
DGPS is assumed to be accurate within 1-2 meters. Standard GPS is assumed accurate within 5-10 meters. 99% of the positional data is DGPS. Unless noted, all GPS/DGPS data is referenced to WGS84 (NAD83). The configuration of the fathometer is as follows: the transducer on the RAFAEL was mounted on a pole at the vessel's bow. Offset between the bow mount and GPS antenna is measured. On ASV IRIS, the subbottom profiler used to measure water depth was mounted directly below the GPS antenna. No measurements were taken of ship's pitch, yaw, heave, or change in draft due to water and fuel usage. Motion of the fathometer is not measured. Horizontal accuracy of the fathometer is assumed to be within +/- 3 meters.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
Ship motion was recorded with a TSS DMS 2-05 Attitude Sensor, mounted on a head above the interferometric Submetrix 2000 Series transducers. Navigation was recorded using Real Time Kinematic Differential Global Positioning System (RTK-DGPS). The interferometric sonar is an angle-measuring system; depth accuracy decreases with increasing horizontal range. The combined angular accuracy of the Submetrix 2000 Series and the TSS DMS 2-05 attitude sensor is documented as 0.1 degrees. Assuming a constant angular accuracy, and using the International Hydrographic Standard (IHO) of a required 0.3 meter accuracy in < 30 meter water depth, all data collected within the survey fall within the IHO accuracy standards. However, vertical accuracy is also directly affected by the accuracy of both the navigation system and tidal measurements. RTK DGPS vertical accuracy is assumed to be 0.2 meters. Tidal elevations were derived from RTK -DGPS heights sent from a survey-specific base station located on St. George Island.
The base station occupied a temporary monument. The x & y positions were calculated for that location using a 3 day average of 12 hour data sets using the Online Positioning User Service (OPUS, National Geodetic Survey) solution. Tidal elevations were calculated from NOAA Tidal Station #8728690 using the same OPUS solution and then applied to the corrected elevations for the base station at St. George Island. Antenna heights were referenced to Mean Lower Low Water (MLLW) for easier comparison of NOAA nautical charts.
Process_Step:
Process_Description:
Bathymetric data were corrected for variations in the speed of sound throughout the water column; sound velocity profiles were acquired throughout the survey area using an Applied MicroSystems SVPlus Sound Velocimeter. These data were downloaded and reformatted to the required format needed for use within University of New Brunswick's Ocean Mapping Group (OMG) SwathEd multibeam processing software. The raw Submetrix 2000 Series data were "unraveled" and reformatted into the OMG format. This process creates several files on disk:
1) bathymetric soundings
2) raw sidescan backscatter
3) navigation
4) parameter files describing the configuration of the system (i.e. offsets between motion reference unit and GPS antenna, etc). This process also incorporates the sound velocity profiles in order to properly trace the rays given the structure of the water column.
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
The OMG formatted bathymetric data were then graphically edited using the SwathEd multibeam processing software. This step enabled editing on a "ping-by-ping" basis, both in the across- and along-track dimension. Spurious or erroneous data were removed. The navigation data were also graphically examined for each line of data.
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
Soundings were corrected to mean lower low water (MLLW) using high-resolution Real-Time Kinematic Global Positioning System (RTKGPS) measurements. The one second RTK data were smoothed in MatLab using a 3rd order polynomial and then merged with each line file in SwathEd.
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
Soundings data were gridded using the weigh_grid routines from SwathEd. Soundings were corrected to mean lower low water during the weigh_grid operation using the real time kinematic differential global positioning navigation files.
The final weigh_grid parameters used were:
weigh_grid -omg -coeffs -butter -lambda 5 -cutoff 20
Max_incidence angle was not used on most lines to allow usage of bathymetry data points from a broader section of the swath. Only lines from rough days, when the vessel heave was large, were gridded with a small incidence angle to maximize the good data from adjacent lanes and reduce the noisy data.
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
Final soundings were gridded to a 5m grid cell resolution using SwathEd weigh_grid command and the following gridding parameters:
weigh_grid -omg -coeffs -butter -power 2 -lambda 1 -cutoff 4 -max_incidence 60
A 5m grid cell size reduced the number of points and a max_incidence of 60 degrees was used to remove the outer soundings which tended to be noisy.
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
The final grid in SwathEd OMG format was imported directly into IVS DMagic software producing a .geo, .dtm, and .shade file. The dtm file was exported to an x,y,z comma delimited file.
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
The comma-delimited x,y,z file of bathymetry was added to ArcMap as an event theme and converted to a point feature class. Two separate x,y,z files and feature classes were processed; one for Apalachicola Bay, and one for St. George Sound.
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x 2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
The remaining geoprocessing steps were completed using one model developed in ArcGIS Modelbuilder. The Model is included in the geodatabase distributed with the Open-File Report. Each of the processing steps used to Create the Model for St. George Sound are described below. The same processing steps were used to create a second Model for Apalachicola Bay using the same steps.
Created empty TIN and added the x,y,z points using the geoprocessing history below:
Create TIN
*Date: 20061027
*Time: 113410
*Tool location: C:\Program Files\ArcGIS\ArcToolbox\Toolboxes\3D Analyst Tools.tbx\CreateTin
*Command issued: CreateTin D:\GIS\FL\rafa06001\ArcGIS\Bathy\BathInterp\Tin\StGTin "PROJCS['WGS_1984_UTM_Zone_16N',GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]],PROJECTION['Transverse_Mercator'],PARAMETER['False_Easting',500000.0],PARAMETER['False_Northing',0.0],PARAMETER['Central_Meridian',-87.0],PARAMETER['Scale_Factor',0.9996],PARAMETER['Latitude_Of_Origin',0.0],UNIT['Meter',1.0]];-10000 -10000 100000;0 100000;0 100000"
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x 2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
Added 5m xyz points to TIN
See geoprocessing history below:
Process:
*Process name: Edit TIN
*Date: 20061027
*Time: 113535
*Tool location: C:\Program Files\ArcGIS\ArcToolbox\Toolboxes\3D Analyst Tools.tbx\EditTin
*Command issued: EditTin D:\GIS\FL\rafa06001\ArcGIS\Bathy\BathInterp\Tin\stgtin "StG_5mc_xyz depth masspoints false;BathClip <None> <None> hardclip false" D:\GIS\FL\rafa06001\ArcGIS\Bathy\BathInterp\Tin\stgtin
Process_Date: 200610
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x 2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
Converted Tin to Raster using Natural Neighbors using floating point and natural neighbors options. Cells size was set at 25m.
Process_Date: 200701
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x 2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
Output Raster was clipped to a polygon boundary delineating the extent of bathymetric data.
Process_Date: 200701
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x 2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
The clipped 25m bathymetric grid was smoothed with a 3x3 low-pass filter.
Process_Date: 200701
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x 2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
Individual 25m smoothed grids of Apalachicola Bay and St. George Sound were merged together to make one grid for both areas.
Process_Date: unknown
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Brian Andrews
Contact_Organization: U.S. Geological Survey
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x 2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). In the case of the depth resolution, the value of 9999 was entered to indicate that the original metadata did not contain the required information. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.
Process_Date: 20160628
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog.
Process_Date: 20170214
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Alan O. Allwardt
Contact_Position: Contractor -- Information Specialist
Contact_Address:
Address_Type: Mailing and Physical
Address: 2885 Mission Street
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060
Contact_Voice_Telephone: 831-460-7551
Contact_Facsimile_Telephone: 831-427-4748
Contact_Electronic_Mail_Address: aallwardt@usgs.gov
Process_Step:
Process_Description: Crossref DOI link was added as the first link in the metadata.
Process_Date: 20191118
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20200908
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
