ALLSHOTS_GEOG.SHP: Point Shapefile of All the Unique Seismic Shot Point Navigation Collected in the Potomac River/Chesapeake Bay from Sept. 6, 2006 to Sept. 8, 2006 on USGS Cruise 06018

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Frequently-anticipated questions:

What does this data set describe?

Title:
ALLSHOTS_GEOG.SHP: Point Shapefile of All the Unique Seismic Shot Point Navigation Collected in the Potomac River/Chesapeake Bay from Sept. 6, 2006 to Sept. 8, 2006 on USGS Cruise 06018
Abstract:
In order to test hypotheses about groundwater flow under and into Chesapeake Bay, geophysical surveys were conducted by U.S. Geological Survey (USGS) scientists on Chesapeake Bay and the Potomac River Estuary in September 2006. Chesapeake Bay resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge, which are contributing to eutrophication. The USGS has performed many related studies in recent years to provide managers with information necessary to make informed decisions about this issue. The research carried out as part of the study described here was designed to help refine nutrient budgets for Chesapeake Bay by characterizing submarine groundwater flow and discharge of groundwater beneath part of the mainstem and a major tributary, the Potomac River Estuary.
  1. How should this data set be cited?

    Bratton, John F. , Foster, David S. , and Cross, VeeAnn A. , 2010, ALLSHOTS_GEOG.SHP: Point Shapefile of All the Unique Seismic Shot Point Navigation Collected in the Potomac River/Chesapeake Bay from Sept. 6, 2006 to Sept. 8, 2006 on USGS Cruise 06018: Open-File Report 2009-1151, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A. , Foster, David S. , and Bratton, John F. , 2010, Continuous Resistivity Profiling and Seismic-Reflection Data Collected in 2006 from the Potomac River Estuary, Virginia and Maryland: Open-File Report 2009-1151, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -76.856667
    East_Bounding_Coordinate: -76.310249
    North_Bounding_Coordinate: 38.295665
    South_Bounding_Coordinate: 37.946077

  3. What does it look like?

    <https://pubs.usgs.gov/of/2009/1151/data/navigation/seismics/allshots_geog.gif> (GIF)
    Thumbnail image showing the location of all the unique seismic shot point navigation collected Sept. 6-8, 2006. The coastline is included for spatial reference.

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 06-Sep-2006
    Ending_Date: 08-Sep-2006
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • Entity point (79510)

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    allshots_geog
    Shapefile attribute table. (Source: ESRI)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    cruiseid
    The cruise identification assigned by the Woods Hole Coastal and Marine Science Center. The original ID was 06018, but upon being converted to a shapefile, the leading zero was dropped by the software. (Source: USGS)

    ValueDefinition
    6018Cruise ID 06018 - the ESRI software treats this field as numeric, so dropped the leading zero of the identifier.

    linename
    The unique identifier for each line of data acquisition. (Source: Software generated.)

    Character set.

    shot
    The seismic shot number associated with the navigation fix. (Source: Software generated.)

    Range of values
    Minimum:1
    Maximum:20000
    Units:shot number

    easting
    Easting (x) coordinate of navigation fix in UTM, Zone 18, NAD83. (Source: Compiler)

    Range of values
    Minimum:337367
    Maximum:385176
    Units:meters

    northing
    Northing (y) coordinate of navigation fix in UTM, Zone 18, NAD83. (Source: Compiler)

    Range of values
    Minimum:4200670
    Maximum:4239508
    Units:meters

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    John F. Bratton
    U.S. Geological Survey
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2254 (voice)
    (508) 457-2310 (FAX)
    jbratton@usgs.gov

Why was the data set created?

The purpose of the data layer is to provide all of the unique shot point navigation associated with the seismic-reflection profiles collected on USGS cruise 06018.. This information can help correlate the seismic-reflection profiles with other features and data in the GIS. This clean, unique shot point navigation is also used as the navigation when loading the seismic data into a digital interpretation software package.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Source_Contribution:
    The seismic acquisition system used on this cruise was a Knudsen Engineering Limited (KEL) 1600 USB system. The system has up to 1.2 kW power and is tuned to work with two Massa 3.5 kHz transducers. The transducers were mounted on an over-the-side mount on the port side of the ship. The transducer draft was 0.7 m below the water surface. This draft offset was not included in the data acquisition. The seismic data acquisition software was SounderSuite-USB Beta. This system failed to acquire navigation data from the DGPS NEMA string on the first two days (Julian day 149 and 150). The software was also not able to record data in SEG-Y standard format. KEL KEB format files were logged to disk. In addition, KEA ASCII files with shot (ping) numbers and times were saved to disk. Shot point navigation was also absent in the KEA files on Julian days 149 and 150. On Julian day 151 a patched version of SounderSuite was received and installed. This version recorded navigation in the KEB and KEA files. SEG-Y recording was still not an option. A time server was used to synchronize the DGPS time on the KEL and HYPACK navigation systems. This was important as KEL SounderSuite records system time. Data were acquired at a 20 micro-second sample interval, 2048 samples for a 40 ms record length. Fire-rate was 0.20 seconds (or 5 shots per second). The KEL SounderSuite software was set up to automatically switch files at shot 20,000. Line 5 switched from file 0005_2006_249_2014_002.keb after shot 13509 to a new file (0005_2006_249_2014_003.keb) while changing display parameters, due to a bug in the acquisition software.

  2. How were the data generated, processed, and modified?

    Date: 2006 (process 1 of 11)
    The KEL SounderSuite acquisition system records two files with every seismic profile. The file containing the seismic data has the extension KEB. The files with the KEA extension are the ASCII navigation files. The prefix filenames are of the format LLLL_YYYY_JJJ_HHMM_FFF where LLLL refers to the line number, YYYY refers to the year of acquisition, JJJ refers to the Julian day of acquisition, HHMM refers to the hour and minute of the start of acquisition, and FFF refers to the file number associated with the line. Because the KEL software was set to increment the file number at 20,000 shots, it's possible to have multiple files for a single line of acquisition. An example filename is: 0024_2006_251_1733_002. This is line 24, collected in the year 2006 on Julian day 251 with a start time of 17:33. This is part 2 of line 24. KEB seismic files were converted to standard SEG-Y files using KEL's PostSurvey version 1.56 software. During the first two days of data acquisition (Julian day 249 and 250 - Sept. 6 and Sept 7), the seismic acquisition software failed to record the navigation data from the DGPS NEMA string in the KEB and KEA files. However, after receiving a patched version of the SounderSuite software, navigation was recorded in the KEB and KEA seismic files. The KEB file is the KEL format seismic profile, while the KEA files is the KEL ASCII navigation file. On the first two days, the KEA files recorded shot number and times. A time server was used to synchronize the GPS time on the KEL with the HYPACK navigation system as the KEL SounderSuite records system time. The prefix filenames are of the format LLLL_YYYY_JJJ_HHMM_FFF where LLLL refers to the line number, YYYY refers to the year of acquisition, JJJ refers to the Julian day of acquisition, HHMM refers to the hour and minute of the start of acquisition, and FFF refers to the file number associated with the line. Because the KEL software was set to increment the file number at 20,000 shots, it's possible to have multiple files for a single line of acquisition. An example filename is: 0024_2006_251_1733_002. This is line 24, collected in the year 2006 on Julian day 251 with a start time of 17:33. This is part 2 of line 24.

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

    Data sources used in this process:
    • *.keb
    • *.kea

    Data sources produced in this process:

    • *.sgy

    Date: 2006 (process 2 of 11)
    All KEB, KEA, and SEG-Y files were transferred to an external hard drive and transferred to a Mac OSX PowerBook for further processing. KEB files were converted to match-filtered standard SEG-Y using KEL's PostSurvey version 1.56 software.

    Data sources used in this process:

    • *.sgy

    Data sources produced in this process:

    • *.sgy

    Date: 2006 (process 3 of 11)
    The processed SEG-Y files were read and converted to SeismicUnix (SU) format trace data.

    Data sources used in this process:

    • *.sgy

    Data sources produced in this process:

    • *.su

    Date: 2006 (process 4 of 11)
    The shot number and time of day were extracted from the SU headers and saved in an ASCII file.

    Date: 2006 (process 5 of 11)
    An AWK script was used to parse the one-second HYPACK navigation files to output time of day and UTM, zone 18 eastings and northings. A navigation file with Julian day, time, and UTM zone 18 coordinates was concatenated for each Julian day (coordinates were rounded to integers).

    Date: 2006 (process 6 of 11)
    The ASCII navigation data were merged with the shot point and time files based on the common field of Julian day, hours, minutes, and seconds using the Unix command "join" on a Mac OS X computer. The output is a shot point navigation file with fixes every five shots (1 second) for the KEL Chirp data. Julian day 151 was processed the same even though position was available in the trace headers. A command line example of the join command is: 
     join 0001_2006_249_1340_001.txt jd249_utm.txt >  0001_2006_249_1340_001.spt

    Date: 2006 (process 7 of 11)
    An AWK script was run within a shell script on a Mac OS X to take the complete seismic navigation and reformat it with Cruise ID, linename, shot, easting and northing. The shell script formatjday: 
    #! /bin/csh
 awk '{FS=" "} {OFS=" "} {printf "%5s %25s %5.0f %6s %7s\n", \
cruise,line,$2,$3,$4,$1} ' cruise=06018 line=$1 $1.spt >> $2.spnav
    This shell script could be called with the following command line example: 
    formatjday 0001_2006_249_1340_001 249

    Data sources used in this process:

    • *.spt where * refers to each navigation file from a given Julian day

    Data sources produced in this process:

    • *.spnav (where * refers to Julian day)

    Date: 2006 (process 8 of 11)
    Each file from a single Julian day was combined into a single text file using the Unix "cat" command.

    Data sources used in this process:

    • *.spnav (where * refers to the Julian day)

    Data sources produced in this process:

    • 06018_knudsen.spnav

    Date: 2006 (process 9 of 11)
    The combined file was renamed with the extension TXT and a header line was added to the file. This file was then added to ArcMap 9.0 as an event theme using Tools - Add XY data and defining the projection as UTM, zone 18, NAD83. The x field is the easting field, and the y field is the northing field. The event theme was then exported as a shapefile by right-mouse clicking on the theme - Data - Export.

    Data sources used in this process:

    • 06018_knudsen.txt

    Data sources produced in this process:

    • allshots.shp

    Date: 2006 (process 10 of 11)
    The first recorded line for line 5 needed to be split into two parts. The file naming in terms of files as the ship travels was originally - part 2, part 1, part 4. In order to better use this shapefile for future work which will sort on filename, shots were renamed from "part 1" to fit in with the direction of boat travel so that now there is part 2, part 3, part 4. (the original part 1 is now part 3).

    Data sources used in this process:

    • allshots.shp

    Data sources produced in this process:

    • allshots.shp

    Date: 2009 (process 11 of 11)
    The shot point shapefile was reprojected to Geographic, NAD83 using ArcMap 9.2, ArcToolbox - Data management Tools - Projections and Transformations - Feature - Project. Because the input file and output file have the same datum, no datum transformation was required.

    Data sources used in this process:

    • allshots.shp

    Data sources produced in this process:

    • allshots_geog.shp

  3. What similar or related data should the user be aware of?

    Norris, Michael W. , and Faichney, Alan K. , 2002, SEG Y rev1 Data Exchange Format: Society of Exploration Geophysicists, Tulsa, OK.

    Online Links:

    Stockwell, John W. Jr., and Cohen, Jack K. , 2008, The New SU User's Manual (version 4.0): Center for Wave Phenomena - Colorado School of Mines, Golden, CO.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    A differential global positioning system (DGPS) was used for the seismic-reflection data. This system was an Ashtech DGPS2 with the navigation being recorded by HYPACK navigation software. The offset from the seismic transducer to the DGPS antenna was 2 meters. This offset was not entered into the software.

  3. How accurate are the heights or depths?

    Although bathymetry was not recorded directly with this system, bathymetry can be derived by tracing the seafloor reflector in the seismic-reflection profiles. The seismic transducers were mounted on an over the side mount on the port side of the ship. The transducer draft was 0.7 m below the water surface. The draft offset was not included in the data acquisition.

  4. Where are the gaps in the data? What is missing?

    This shapefile represents all the unique shot point navigation collected during USGS cruise 06018.

  5. How consistent are the relationships among the observations, including topology?

    These points were visually checked to make sure they were viable fixes. All days were handled the same way, even though the acquisition software changed during the cruise.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None.
Use_Constraints:
The public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.

  1. Who distributes the data set? (Distributor 1 of 1)

    John F. Bratton
    U.S. Geological Survey
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2254 (voice)
    (508) 457-2310 (FAX)
    jbratton@usgs.gov

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Neither the U.S. government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. 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 materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    This WinZip file contains data available in ESRI point shapefile format. The user must have software capable of uncompressing the WinZip file and reading/displaying the shapefile.

Who wrote the metadata?

Dates:
Last modified: 25-Mar-2010
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
Woods Hole Coastal and Marine Science Center
Woods Hole, MA 02543-1598

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.6 on Thu Mar 25 13:10:22 2010