ALLASV_NODUPES_SORT.SHP: All Autonomous Surface Vessel IRIS Shotpoint Navigation for Chirp Seismic Data in Apalachicola Bay collected on U.S. Geological Survey Cruise 06001 (Geographic, WGS84)

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Frequently-anticipated questions:

What does this data set describe?

Title:
ALLASV_NODUPES_SORT.SHP: All Autonomous Surface Vessel IRIS Shotpoint Navigation for Chirp Seismic Data in Apalachicola Bay collected on U.S. Geological Survey Cruise 06001 (Geographic, WGS84)
Abstract:
Apalachicola Bay and St. George Sound contain the largest oyster fishery in Florida, and the growth and distribution of the numerous oyster reefs here are the combined product of modern estuarine conditions and the late Holocene evolution of the bay. A suite of geophysical data and cores were collected during a cooperative study by the U.S. Geological Survey, the National Oceanic and Atmospheric Administration Coastal Services Center, and the Apalachicola National Estuarine Research Reserve to refine the geology of the bay floor as well as the bay's Holocene stratigraphy. Sidescan-sonar imagery, bathymetry, high-resolution seismic profiles, and cores show that oyster reefs occupy the crests of sandy shoals that range from 1 to 7 kilometers in length, while most of the remainder of the bay floor is covered by mud. The sandy shoals are the surficial expression of broader sand deposits associated with deltas that advanced southward into the bay between 6,400 and 4,400 years before present. The seismic and core data indicate that the extent of oyster reefs was greatest between 2,400 and 1,200 years before present and has decreased since then due to the continued input of mud to the bay by the Apalachicola River. The association of oyster reefs with the middle to late Holocene sandy delta deposits indicates that the present distribution of oyster beds is controlled in part by the geologic evolution of the estuary. For more information on the surveys involved in this project, see <http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2005-001-FA> and <http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2006-001-FA>.
  1. How should this data set be cited?

    Twichell, David C. , and Cross, VeeAnn A. , 2012, ALLASV_NODUPES_SORT.SHP: All Autonomous Surface Vessel IRIS Shotpoint Navigation for Chirp Seismic Data in Apalachicola Bay collected on U.S. Geological Survey Cruise 06001 (Geographic, WGS84): Open-File Report 2012-1003, 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, V.A., Twichell, D.C., Foster, D.S., and O'Brien, T.F., 2012, Apalachicola Bay Interpreted Seismic Horizons and Updated IRIS Chirp Seismic-Reflection Data: Open-File Report 2012-1003, 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: -85.062710
    East_Bounding_Coordinate: -84.809553
    North_Bounding_Coordinate: 29.746692
    South_Bounding_Coordinate: 29.618457

  3. What does it look like?

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

    Beginning_Date: 03-Jun-2006
    Ending_Date: 27-Jun-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 (122926)

    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 D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?

    allasv_nodupes_sort
    ESRI point shapefile (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.

    filename
    Text field with the original filename prepended by "asv06" to indicate the IRIS as the source of data collection. (Source: Data processor.)

    Character set.

    shot
    Seismic shot number corresponding to the navigation fix. (Source: Data processor.)

    Range of values
    Minimum:1
    Maximum:39499
    Units:seismic shot

    longitude
    Longitude coordinate of the point location in decimal degrees, WGS84. (Source: Data processor.)

    Range of values
    Minimum:-85.06271
    Maximum:-84.809553
    Units:decimal degrees

    latitude
    Latitude coordinate of the point in decimal degrees, WGS84. (Source: Data processor.)

    Range of values
    Minimum:29.618457
    Maximum:29.746692
    Units:decimal degrees

    easting
    Easting coordinate of the point rounded to the nearest meter based on UTM, Zone 16, WGS84. (Source: Data processor.)

    Range of values
    Minimum:687471
    Maximum:711848
    Units:meters

    northing
    Northing coordinate of the point rounded to the nearest meter based on UTM, Zone 16, WGS84. (Source: Data processor.)

    Range of values
    Minimum:3278111
    Maximum:3292657
    Units:meters

    year
    Calendar year the data were collected. (Source: Data processor.)

    ValueDefinition
    2006Year in which the data were collected.

    jday
    This number represents the Julian day of data collection based on UTC time. Julian day is the integer number representing the interval of time in days since January 1 of the year. (Source: Data processor.)

    Range of values
    Minimum:154
    Maximum:178
    Units:day

    seistime
    UTC time in the format HHMMSS of the time of the data point collection. (Source: Data processor.)

    Although the value is represented as a number, the number as a whole doesn't have a particular meaning. Only when the individual parts for hours, minutes, and seconds are broken out does the number have meaning.

    uniqueid
    Text field providing a unique ID for the seismic line along which these data were collected. The first 3 numbers of the name represent Julian day. This convention was necessary because of the repeat use of linenames on different days. (Source: Data processor.)

    Character set.

    lmarkname
    An abbreviated text field which provides a unique line name associated with each point of data collection. The shorter name is easier to work with in the seismic interpretation software. (Source: Data processor.)

    Character set.

    discover
    Text field indicating if the recording software of the seismic line was the Discover software. (Source: Data processor.)

    ValueDefinition
    noThe Discover software was not used to record the data.
    yesThe Discover software was used to record the data.

    divisors
    The divisor needed to convert the navigation recorded in the SEG-Y headers to decimal degrees. The first number represents the divisor of the longitude, while the second number indicates the divisor needed for the latitude. (Source: Data processor.)

    Character set.

    imgname
    The original file name of the acquired seismic line, which also corresponds to the prefix of the JPEG image filename associated with the seismic line. (Source: Data processor.)

    Character set.

    Entity_and_Attribute_Overview:
    The platform used to collect the original seismic data was the Woods Hole Coastal and Marine Science Center's Autonomous Surface Vessel (ASV) IRIS (Independently (or) Remotely Influenced Surveyor). Details of the platform can be found on the following web page: <http://woodshole.er.usgs.gov/operations/sfmapping/iris.htm>. IRIS is configured with an EdgeTech FFSB 424 chirp sub-bottom profiler that operates within a 4-24 kHz frequency range. The vehicle is navigated using Real-Time Kinematic (RTK) GPS. The antenna is mounted directly on the platform to minimize navigational error.

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?

    David C. Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov

Why was the data set created?

This shapefile represents all the unique shotpoint navigation for the IRIS Chirp seismics collected in Apalachicola Bay, Florida. This also serves as the archive of these navigation data.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Source_Contribution:
    The data were collected using the USGS WHCMSC Autonomous Surface Vessel (ASV) IRIS. This system is designed to operate in shallow water (1-5 meters). IRIS is a catamaran platform 3 meters in length, 1.2 meters in width, and approximately 118 kilograms. The vehicle is operated remotely through a wireless modem network enabling real-time monitoring of data acquisition. The system is navigated using a ZXW RTK augmented GPS system enclosed on a platform in the middle of the catamaran. An enclosed onboard micro-processor-based motor controller provides signals for speed and steering to hull-mounted brushless direct-current thrusters. A center-mounted keel encloses the chirp dual-frequency (100/400 kHz model 4200 EdgeTech) sidescan-sonar transducers and EdgeTech 424 chirp seismic-reflection hydrophones. Mounted in the port hull are the EdgeTech 424 chirp seismic-reflection transducer and a single-beam 235 kHz echosounder. A Sony IP based wireless video camera is installed on the mast of IRIS for the purpose of obstacle avoidance. An onboard Fluxgate magnetometer provides heading, heave, pitch, and roll. IRIS is powered by 2-4 24-volt NiMH batteries located in each hull and has an approximate run-time of five hours at 4 knots.

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

    Date: 2006 (process 1 of 10)
    The seismic data were acquired with an EdgeTech SB-424 sub-bottom profiler and recorded in JSF format using JSTAR, EdgeTech's acquisition software. The research effort within Apalachicola Bay represented the first use of IRIS in full survey mode. As such, the system needed to be 'rung-out' during the first several days of surveying. A file naming convention developed over the first few days of surveying and acquisition settings (hardware and software) were modified several times until standardized settings could be established for Apalachicola Bay. Initial trouble-shooting dealt with several issues including a variation in the field in which navigation was stored within the JSF header and in the resolution of the navigation (seconds of arc vs. minutes of arc). Correcting these issues required re-running particular files though EdgeTech's DISCOVER software and saving new JSF files. Files that were saved through DISCOVER are signified by a 'yes' in the 'discover' field within the shapefile. A 'no' within the 'discover' field indicates that the JSF file was correct in its original format; re-running through DISCOVER was not required. The JSF files were then converted to SEG-Y format using jsf2segy, a C-program written by Tom O'Brien at the Woods Hole Coastal and Marine Science Center, U.S. Geological Survey.

    Person who carried out this activity:

    Tom O'Brien
    U.S. Geological Survey
    Marine Geophysical Systems Expert
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2246 (voice)
    (508) 457-2310 (FAX)
    tobrien@usgs.gov

    Date: 2006 (process 2 of 10)
    These original SEG-Y files are in IEEE format and were converted to IBM floating point using SIOSEIS. In addition to this conversion, the shot numbers have been renumbered in order to start at one.

    Person who carried out this activity:

    David S. Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@usgs.gov

    Date: 2006 (process 3 of 10)
    A csh script utilized Seismic Unix (v 4.0) to extract all of the unique navigation points from the SEG-Y header within the seismic data. These values were written to a comma-delimited text file. In addition to extracting the navigation, the csh script was used to generate JPEG images of each seismic profile. Due to modifications to acquisition parameters during the initial days of surveying, the format in which navigation was stored in the SEG-Y headers varies: navigation is stored in either decimal arc seconds (0.01) or decimal arc minutes (0.0001). In order to properly extract and convert navigation to latitude/longitude divisors of 360000 and 600000 were used for decimal arc seconds and decimal arc minutes, respectively.
    Prior to JD172, the acquisition system did not consistently record longitude as a negative value (western hemisphere). Thus, either 600000 or -600000 was used to convert arc minutes to longitude based on whether the acquisition software recorded negative or positive longitude values. The divisors necessary for proper navigation extraction are contained in the attribute field "divisors" and are in the format "longitude divisor/ latitude divisor". This process step and all subsequent process steps were performed by the same person - VeeAnn A. Cross.

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

    Date: 2006 (process 4 of 10)
    The individual comma-delimited text files were then concatenated to generate a single navigation text file. This file was edited to remove invalid positions (usually latitude and longitude values of 0). In addition, calendar year and Julian day values were edited as necessary in order to reflect appropriate values. Finally, a header was added to the navigation text file in order to describe each column of data.

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

    Date: 2006 (process 5 of 10)
    The navigation text file was added to ArcMap 9.1 as an XY point event layer and converted to a point shapefile.

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

    Date: 2007 (process 6 of 10)
    The attribute "lmarkname" was added to the shapefile. This attribute will be used as the unique line name when loading the data into Landmark SeisWorks software. Seismic lines containing circles or turns were broken into multiple segments and assigned an unique line name by appending an "a" or "b" etc. to the line name. Landmark can load a portion of a SEG-Y file by loading the line segment that corresponds to the shot point navigation. (i.e. Splitting a SEGY file into segments is unnecessary, only the navigation needs to be split). During the initial days of surveying, the seismic acquisition system simultaneously recorded multiple files per survey line, creating some data redundancies. These overlapping portions of the survey line do not have a value entered in the "lmarkname" attribute

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

    Date: 2007 (process 7 of 10)
    All records that do not have a blank in the "lmarkname" attribute are selected and saved to a new point shapefile that will be used to load SEG-Y data into Landmark software.

    Data sources used in this process:

    • allasvpntnav_mod.shp

    Data sources produced in this process:

    • allasv4landmark.shp

    Date: 2008 (process 8 of 10)
    Points with duplicate location need to be removed. Within ArcMap 9.2, using XTools Pro v. 5.2 - Table operations - Find Duplicates set the output to allasv_nodupes.shp. Other parameters: add feature to current map, create spatial index, compare by shape - check box to remove duplicates; index field name - index. Deselect the option to add ID field of the source feature. After this was done, a comparison showed the original shapefile had 123157 points and the new one had 122950 points.

    Date: 2008 (process 9 of 10)
    Sort the new shapefile using VACExtras v 2.0, VAC Extras - Feat Conv - Table Sort. Primary sort is lmarkname in ascending order, secondary sort is shot in ascending order. Output: allasv_nodupes_sort.shp.

    Date: 2008 (process 10 of 10)
    The attribute imgname was added to the shapefile. This reflects the prefix of the filename associated with the seismic-reflection profile JPEG image associated with the line. These names are not unique, as file names were repeated on different survey days.

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

    Twichell, D.C., Andrews, B.D., Edmiston, H.L., and Stevenson, W.R., 2007, Geophysical mapping of oyster habitats in a shallow estuary; Apalachicola Bay, Florida: Open-File Report 2006-1381, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Twichell, D.C., Pendleton, E.A., Poore, R.Z., Osterman, L.E., and Kelso, K.W., 2009, Vibracore, radiocarbon, microfossil, and grain-size data from Apalachicola Bay, Florida: Open-File Report 2009-1031, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Bergeron, E., Worley, C.R., and O'Brien, T.F., 2007, Progress in the development of shallow-water mapping systems: using an autonomous surface vehicle for shallow-water geophysical studies: Sea Technology v. 48, no. 6, p. 10-15, Compass Publications, Inc., Arlington, VA.

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

  1. How well have the observations been checked?

    Although the "seistime" attribute is extracted from the header of the seismic data files, it's clear there were some problems with the information recorded in the header. Periodically the time sequence is out of order. For instance, times (in the format hhmmss) on consecutive shots read 161047, 161048, 161018, 161050. Obviously, the 161018 is chronologically out of order. These problems were not fixed in the attribute table.

  2. How accurate are the geographic locations?

    IRIS was navigated with a Real-Time Kinematic (RTK) GPS, with the GPS antenna mounted directly over the seismic transducer. This system can provide positions to within 0.1 meters. However, due to some errors with the acquisition software, this accuracy is reduced. The accuracy is approximately 2 m given the constraints of the acquisition system.

  3. How accurate are the heights or depths?

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

    No data were acquired on the following dates: 6/8/2006, 6/10/2006 6/12/2006, 6/13/2006, 6/15/2006, 6/16/2006, 6/17/2006, 6/18/2006, 6/19/2006, 6/20/2006. These dates correspond to Julian days 159, 161, 163, 164, 166, 167, 168, 169, 170, and 171 respectively. In addition, lines for which no valid seismic data were available, or extremely short lines, were deleted. Some lines acquired seismic data, but little or no navigation. These lines are also excluded. One line was re-run, so the original problematic line was excluded. The list of collected seismic lines excluded from this and subsequent datasets is as follows: Julian day 155 - apalachicola000 (rerun), apalachicola020 (too short), apalachicola027 (insufficient navigation). Julian day 160 - day160001 (insufficient navigation). Julian day 165 - day165001 (too short). Julian day 172 - JD172010 (too short), JD172014 (too short), JD172025 (too short). Julian day 173 - JD173009 (too short). Julian day 174 - JD174010 (too short).

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

    No duplicate features are present. Inconsistencies exist in the filenaming convention for individual seismic data collection lines. Because the filenames reflect the original data file names acquired in the field, they were left alone.

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:
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 originators of this dataset.

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

    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

  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: 12-Apr-2012
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
384 Woods Hole Rd.
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 Wed Apr 18 17:10:34 2012