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Short Citation:
Office for Coastal Management, 2022: Bathymetric ArcRaster Grid of Apalachicola Bay and St. George Sound, Florida (25m),

Item Identification

Title: Bathymetric ArcRaster Grid of Apalachicola Bay and St. George Sound, Florida (25m)
Short Name: fl_ab06_bath-meta
Status: Completed
Publication Date: 2007

These data were collected under a cooperative mapping program between the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration Office for Coastal Management (NOAA\OCM), and the Apalachicola National Estuarine Research Reserve (NERR). The primary objectives of this program were to collect marine geophysical data to develop a suite of seafloor maps to better define the extent of oyster habitats, the overall seafloor geology of the bay and provide updated information for management of this resource. In addition to their value for management of the bay's oyster resources, the maps also provide a geologic framework for scientific research and the public.

High-resolution bathymetry, backscatter intensity, and seismic profile data were collected over 230 square kilometers of the floor of the bay. The study focused on Apalachicola Bay and Western St. George Sound portions of the estuary mostly in depths > 2.0 meters.

Original contact information:

Contact Name: Brian Andrews

Contact Org: U.S. Geological Survey

Title: Geographer

Phone: 508-548-8700 x2348



The purpose of this dataset is to produce a bathymetric grid of the area within the survey boundary in St. George Sound and Apalachicola Bay.

The purpose of these data is to represent the swath bathymetry in a courser grid cell resolution but cover the gaps between survey lines. In shallow areas less than 2m deep the digitized seafloor from the ASV seismic data was used to provide single beam bathymetry.



Supplemental Information:

These data are a bathymetric grid of Apalachicola Bay and St. George Sound generated from swath sounding gridded at 5m. Refer to processing steps under data quality section for detailed methods.


Theme Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Science Keywords
Global Change Master Directory (GCMD) Science Keywords
Global Change Master Directory (GCMD) Science Keywords
General ArcGIS Raster
General CMGP
General Coastal and Marine Geology Program
General field activity serial number 05001
General field activity serial number 06001
General Interferometric Sonar
General Marine Geology
General Seafloor
General seafloor mapping
General Swath Bathymetry
General U.S. Geological Survey
General USGS
General WHSC
General Woods Hole Science Center
ISO 19115 Topic Category elevation
ISO 19115 Topic Category oceans

Temporal Keywords

Thesaurus Keyword
General 2005
General 2006

Spatial Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Location Keywords
General Apalachicola Bay
General Apalachicola National Estuarine Research Reserve
General Florida
General Gulf of Mexico
General St. George Sound
General United States

Physical Location

Organization: Office for Coastal Management
City: Charleston
State/Province: SC

Data Set Information

Data Set Scope Code: Data Set
Maintenance Frequency: None Planned
Data Presentation Form: Map (digital)
Distribution Liability:

NOAA manages much of the data to users of digital geographic data. NOAA is in no way condoning or endorsing the application of this data for any given purpose.It is the sole responsibility of the user to determine whether or not the data is suitable for the intended purpose. It is also the obligation of the user to apply the data in an appropriate and conscientious manner.NOAA provides no warranty,nor accepts any liability occurring from any incomplete,incorrect, or misleading data, or from any incorrect,incomplete, or misleading use of the data. Much of the data is based on and maintained with ARC/GIS software developed by the Environmental Systems Research Institute (ESRI).In addition, much of the information presented uses conventions and terms popularized by ARC/GIS and its user community. NOAA in no way represents the interests of ESRI,nor acts as agents for them. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Support Roles

Data Steward

CC ID: 610734
Date Effective From: 2007
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


CC ID: 610736
Date Effective From: 2007
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Metadata Contact

CC ID: 610737
Date Effective From: 2007
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Point of Contact

CC ID: 610735
Date Effective From: 2007
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 610743
W° Bound: -85.096558
E° Bound: -84.753126
N° Bound: 29.789051
S° Bound: 29.597035

Extent Group 1 / Time Frame 1

CC ID: 610739
Time Frame Type: Discrete
Start: 2005-03-14

Extent Group 1 / Time Frame 2

CC ID: 610740
Time Frame Type: Discrete
Start: 2006-05-29

Extent Group 1 / Time Frame 3

CC ID: 610741
Time Frame Type: Discrete
Start: 2005-04-13

Extent Group 1 / Time Frame 4

CC ID: 610742
Time Frame Type: Discrete
Start: 2006-06-27

Spatial Information

Spatial Representation

Representations Used

Grid: Yes

Grid Representation 1

CC ID: 610724
Dimension Count: 3
Cell Geometry: Area
Transformation Parameters Available?: No

Axis Dimension 1

Dimension Type: Row
Size: 828

Axis Dimension 2

Dimension Type: Column
Size: 1315

Axis Dimension 3

Dimension Type: Vertical
Size: 1

Access Information

Security Class: Unclassified
Data Access Procedure:

Data can be downloaded via the World Wide Web (WWW);

Data Access Constraints:


Data Use Constraints:

Data are not intended for navigational use.

These data should not be used at resolutions for which it is not intended.

Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.

Distribution Information

Distribution 1

CC ID: 750334
Download URL:
File Name: Bulk Download

FTP download of data files.

Distribution 2

CC ID: 750335
Download URL:

Downloadable Data



CC ID: 750337
URL Type:
Online Resource


CC ID: 750338
Name: NOAA's Office for Coastal Management (OCM) website
URL Type:
Online Resource

Information on the NOAA Office for Coastal Management (OCM)


CC ID: 750339
Name: Browse Graphic
URL Type:
Browse Graphic
Browse Graphic
File Resource Format: JPEG

color coded image

Activity Log

Activity Log 1

CC ID: 610775
Activity Date/Time: 2017-03-30

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 610774
Activity Date/Time: 2017-11-14

Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using '' script. Contact Tyler Christensen (NOS) for details.

Activity Log 3

CC ID: 717837
Activity Date/Time: 2018-02-08

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 750336
Activity Date/Time: 2018-04-11

Partial upload to move data access FTP links to Distribution Info and remove broken URLs.

Technical Environment


Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog

Data Quality

Horizontal Positional Accuracy:

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:

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.

Completeness Report:

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.

Conceptual Consistency:

These data have not been quantitatively compared to previous hydrographic data, although they generally agree with qualitative comparison of published NOAA charts.


Process Steps

Process Step 1

CC ID: 610710

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/Time: 2006-10-01 00:00:00

Process Step 2

CC ID: 610711

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/Time: 2006-10-01 00:00:00

Process Step 3

CC ID: 610712

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/Time: 2006-10-01 00:00:00

Process Step 4

CC ID: 610713

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/Time: 2006-10-01 00:00:00

Process Step 5

CC ID: 610714

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/Time: 2006-10-01 00:00:00

Process Step 6

CC ID: 610715

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/Time: 2006-10-01 00:00:00

Process Step 7

CC ID: 610716

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/Time: 2006-10-01 00:00:00

Process Step 8

CC ID: 610717

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/Time: 2006-10-01 00:00:00

Process Step 9

CC ID: 610718

Added 5m xyz points to TIN

See geoprocessing history below:


*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/Time: 2006-10-01 00:00:00

Process Step 10

CC ID: 610719

Converted Tin to Raster using Natural Neighbors using floating point and natural neighbors options. Cells size was set at 25m.

Process Date/Time: 2007-01-01 00:00:00

Process Step 11

CC ID: 610720

Output Raster was clipped to a polygon boundary delineating the extent of bathymetric data.

Process Date/Time: 2007-01-01 00:00:00

Process Step 12

CC ID: 610721

The clipped 25m bathymetric grid was smoothed with a 3x3 low-pass filter.

Process Date/Time: 2007-01-01 00:00:00

Process Step 13

CC ID: 610722

Individual 25m smoothed grids of Apalachicola Bay and St. George Sound were merged together to make one grid for both areas.

Process Date/Time: 2007-01-01 00:00:00

Child Items

Rubric scores updated every 15m

Rubric Score Type Title
Entity fl_ab06_bath

Catalog Details

Catalog Item ID: 47876
GUID: gov.noaa.nmfs.inport:47876
Metadata Record Created By: Anne Ball
Metadata Record Created: 2017-11-14 12:57+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2022-08-09 17:11+0000
Metadata Record Published: 2018-04-11
Owner Org: OCM
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2018-04-11
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2019-04-11