RESGPSPNTS_JD249.SHP: Navigation and Bathymetry Points of Ship Position During Continuous Resistivity Profile Data Collection in the Potomac River/Chesapeake Bay on Sept. 6, 2006 on USGS Cruise 06018

Metadata also available as - [Outline] - [Parseable text]

Frequently-anticipated questions:


What does this data set describe?

Title:
RESGPSPNTS_JD249.SHP: Navigation and Bathymetry Points of Ship Position During Continuous Resistivity Profile Data Collection in the Potomac River/Chesapeake Bay on Sept. 6, 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?

    Cross, VeeAnn A. , 2010, RESGPSPNTS_JD249.SHP: Navigation and Bathymetry Points of Ship Position During Continuous Resistivity Profile Data Collection in the Potomac River/Chesapeake Bay on Sept. 6, 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: -76.454833
    East_Bounding_Coordinate: -76.310367
    North_Bounding_Coordinate: 38.295767
    South_Bounding_Coordinate: 37.946450

  3. What does it look like?

    <https://pubs.usgs.gov/of/2009/1151/data/navigation/resistivity/resgpspnts_jd249.gif> (GIF)
    Thumbnail image showing the location of resistivity navigation points collected Sept. 6, 2006. The coastline is included for spatial reference.

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

    Calendar_Date: 06-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 (6141)

    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.

      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Local surface
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    resgpspnts_jd249
    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.

    longitude
    Longitude coordinate of the point in decimal degrees, NAD83. (Source: U.S. Geological Survey)

    Range of values
    Minimum:-76.454833
    Maximum:-76.310367
    Units:decimal degrees

    latitude
    Latitude coordinate of the point in decimal degrees, NAD83. (Source: U.S. Geological Survey)

    Range of values
    Minimum:37.94645
    Maximum:38.295767
    Units:decimal degrees

    gpstime
    GPS time in the format HH:MM:SS. GPS time is +4 hours from local time during the survey. (Source: U.S. Geological Survey)

    Character set.

    gpsdate
    The date recorded in the GPS navigation in the format DDMMYY. Because of the time offset from local time, this date could actually be different than the local acquisition date. (Source: U.S. Geological Survey)

    Character set.

    depth_m
    Depth of the water below the fathometer in meters recorded by the ship's fathometer/navigation system. (Source: U.S. Geological Survey)

    Range of values
    Minimum:1.7
    Maximum:21.200001
    Units:meters

    linename
    The alphanumeric name corresponding to the prefix of the GPS filename. This name reflects the name assigned to the line of data acquisition and incorporates modifiers to reflect modification of the GPS file. (Source: U.S. Geological Survey)

    Character set.

    gps_src
    The system from which the navigation point was derived. On this day those values came from the Lowrance system. (Source: U.S. Geological Survey)

    Character set.

    bathy_src
    The system from which the bathymetric value was acquired. On this day, all bathymetry came from the ship navigation/fathometer system. (Source: U.S. Geological Survey)

    Character set.


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 this point shapefile is to provide the ship's position and bathymetric values during the collection of continuous resistivity profile data.


How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Source_Contribution:
    The continuous resistivity profile (CRP) system used on this cruise was an AGI SuperSting marine system described at the website: www.agiusa.com/marinesystem.shtml. The particular system used for this acquisition was a 100-m streamer with an 11 electrode array with electrodes spaced 10 meters apart. The source electrodes are graphite, while the receiver electrodes are stainless steel. A dipole-dipole configuration was used for the data collection in which two fixed current electrodes are assigned with the measurement of voltage potential between electrode pairs in the remaining electrodes. Each line of data acquisition records several files. The two files necessary for processing are the *.stg and the *.gps file. The STG file contains the resistivity data, while the GPS file contains the navigation information. The navigation system used in concert with the CRP system is a Lowrance LMS-480M with an LGC-2000 GPS antenna and a 200 kHz fathometer transducer. The transducer also contains a temperature sensor which was not working on Julian Day 249. Lowrance indicates the speed of sound used by the system is 4800 feet/second. On the first day of data collection (Julian Day 249, Sept. 6, 2006) the Lowrance transducer was side-mounted mid-ship on the port side of the boat. The remainder of the cruise the transducer was side-mounted mid-ship of the starboard side of the boat. The CRP system images the subsurface electrical properties of an estuarine, riverine or lacustrine environment. Resistivity differences can be attributed to subsurface geology (conductive vs less conductive layers) and hydrogeologic conditions with fresh water exhibiting high resistivity and saline conditions showing low resistivity.

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

    Date: 2006 (process 1 of 13)
    The data files were transferred from the acquisition computer via a USB thumb drive. The first step is to check the navigation recorded in the *.gps file for each line of acquisition. Although the navigation fixes themselves appear to be okay, the fathometer data is not. To verify this, I extracted the $GPRMC line from the CRP GPS files using an AWK script. (* refers to the line name, which for this day are l1f1, l2f1, l3f1, l4f1, l5f1 and l6f1)
    awkpullgprmc:
    BEGIN {
    FS = ","
    }
    {
    FS = ","
    if ($1=="$GPRMC")
    {
    print $0
    }
    endif
    }
    

    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:
    • *.gps

    Data sources produced in this process:

    • *.gprmc

    Date: 2006 (process 2 of 13)
    Used an AWK script to reformat the GPRMC navigation to a comma-delimited ANSI text navigation file suitable for loading in the GIS. (* refers to the line name, which for this day are l1f1, l2f1, l3f1, l4f1, l5f1 and l6f1). The text editor VI was used to add the necessary header line to each file.
    awk_justgprmc:
    BEGIN {
    FS=","
    }
    {
    FS= ","
    ARGC = 2
    if ($1=="$GPRMC") {
    gpstime = $2
    hr = substr($2,1,2)
    min = substr($2,3,2)
    sec = substr($2,5,2)
    latdeg = substr($4,1,2)
    latmin = substr($4,3,6)
    londeg = substr($6,2,2)
    lonmin = substr($6,4,6)
    declat = latdeg + (latmin/60)
    declon = (londeg + (lonmin/60)) * -1
    date = $10
    day = substr($10,1,2)
    month = substr($10,3,2)
    year = substr($10,5,2)
    printf("%8.6f, %8.6f, %s:%s:%s, %s\n",declon, declat, hr, min, sec, date)
    }
    }
    

    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:
    • *.gprmc

    Data sources produced in this process:

    • *gprmc.txt

    Date: 2006 (process 3 of 13)
    Using ArcView 3.3 this comma-delimited ANSI text file was loaded as an event theme. This event theme was then saved as a shapefile using Theme - Convert to shapefile. (* refers to the line name, which for this day are l1f1, l2f1, l3f1, l4f1, l5f1 and l6f1)

    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:
    • *gprmc.txt

    Data sources produced in this process:

    • *.shp

    Date: 2006 (process 4 of 13)
    An ANSI text file containing the ship's navigation and fathometer information was transferred from the ship's system using a thumb drive.

    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 produced in this process:
    • usgs090606.nav

    Date: 2006 (process 5 of 13)
    This text file was reformatted using an AWK script into a comma-delimited ANSI text file suitable for loading in the GIS.
    awknav:
    {
    shipdate = $1
    gpstime = $2
    latdeg = substr($5,1,2)
    latdecmin = $6
    declat = latdeg + (latdecmin/60)
    londeg = substr($7,1,3)
    londecmin = $8
    declon = -1 * (londeg + (londecmin/60))
    depmeters = $10
    printf("%s, %s, %9.6f, %9.6f, %s\n",shipdate, gpstime, declat, declon, depmeters)
    }
    

    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:
    • usgs090606.nav

    Data sources produced in this process:

    • shippnts_249.txt

    Date: 2006 (process 6 of 13)
    The ANSI text file was loaded into ArcView 3.3 as an event theme and then saved as a shapefile using Theme - convert to shapefile.

    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:
    • shippnts_249.txt

    Data sources produced in this process:

    • shippnts_249.shp

    Date: 2006 (process 7 of 13)
    Within ArcView 3.3 I used the spatial join capabilities to join the ship navigation and fathometer information to each line of resistivity navigation. This is accomplished by opening both attribute tables in ArcView. Then make the source table active (the table that I want to join to the other table). In this case, that's the attribute table for shippnts_249.shp. Within this table, click the Shape field's name. Then make the other attribute table active (*.shp where * represents the line name such as l1f1). Select the Shape field's name. Then from the table menu, choose "Join". This essentially finds the closest positional point in shippnts_249.shp and joins it to the *.shp attribute table. (* refers to the line name, which for this day are l1f1, l2f1, l3f1, l4f1, l5f1 and l6f1)

    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:
    • *.shp
    • shippnts_249.shp

    Date: 2006 (process 8 of 13)
    The only information I need from this joined table is the bathymetry information. So using the table properties, I turn off (uncheck the visible option) everything but the depth values. Once this is done, I use File - Export to export the table to a delimited text file. (* refers to the line name, which for this day are l1f1, l2f1, l3f1, l4f1, l5f1 and l6f1)

    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:
    • *.shp

    Data sources produced in this process:

    • *_shipbathy.txt

    Date: 2006 (process 9 of 13)
    I then ran an AWK script which would take the each line of the bathymetry information and convert it to the $SDDPT format that a GPS system would record. (* refers to the line name, which for this day are l1f1, l2f1, l3f1, l4f1, l5f1 and l6f1). The $SDDPT refers to the water depth relative to the transducer, in meters. The sentence is of the format "$SDDPT, DATA_METERS, OFFSET_METERS, MAXIMUM_METERS*hh<0D><0A> where the portion after the * is a checksum value. I manually defined everything except the actual depth values, since those are the only values I'll use.
    awk_sddpt:
    {
    depthval = $1
    printf("$SDDPT,%s,0.0*65\n",depthval)
    }
    

    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:
    • *_shipbathy.txt

    Data sources produced in this process:

    • *.sddpt

    Date: 2006 (process 10 of 13)
    For every line in the extracted GPRMC data, I now have a separate files with the same number of lines containing bathymetry information in the $SDDPT format. Using CYGWIN (a UNIX like environment that runs under Windows) I use the "paste" command to join the two files using a newline character as the delimiter between the two files. Essentially what this does is generate a file with a line of GPRMC data, then SDDPT and so for and so on. The syntax with the paste command I used for the resistivity navigation is: paste -d '\n' filename1 filename2 > output where filename1 is the GPRMC text file, filename2 is the bathymetry text file, and the output is the repaired GPS navigation file. (* refers to the line name, which for this day are l1f1, l2f1, l3f1, l4f1, l5f1 and l6f1)

    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:
    • *.gprmc
    • *.sddpt

    Data sources produced in this process:

    • *fix.gps

    Date: 2006 (process 11 of 13)
    I then ran an AWK script on the resulting GPS files to generate a single comma-delimited text file with the information of interest. I then used VI to add the appropriated header line.
    AWK script awkit:
    BEGIN {
    FS=","
    }
    {
    FS= ","
    ARGC = 2
    if ($1=="$GPRMC") {
    gpstime = $2
    hr = substr($2,1,2)
    min = substr($2,3,2)
    sec = substr($2,5,2)
    latdeg = substr($4,1,2)
    latmin = substr($4,3,6)
    londeg = substr($6,2,2)
    lonmin = substr($6,4,6)
    declat = latdeg + (latmin/60)
    declon = (londeg + (lonmin/60)) * -1
    date = $10
    day = substr($10,1,2)
    month = substr($10,3,2)
    year = substr($10,5,2)
    }
    else if ($1=="$SDDPT") {
    depth = $2
    printf("%8.6f, %8.6f, %s:%s:%s, %s, %s, %s\n",declon, declat, hr, min, sec, date, depth, ARGV[2])
    }
    }
    
    
    The running of the script was initiated with a simple executable shell script under CYGWIN (a Unix like environment that runs under Windows
    "doawk":
    files=`ls *.gps | cut -d. -f1`
    for file in $files
    do
    awk -f awkit $file.gps $file >> resnav_jd249.txt
    done
    

    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:
    • l1f1fix.gps
    • l2f1fix.gps
    • l3f1fix.gps
    • l4f1fix.gps
    • l5f1fix.gps
    • l6f1fix.gps

    Data sources produced in this process:

    • resnav_jd249.txt

    Date: 2009 (process 12 of 13)
    The comma-delimited text file was imported to ArcMap 9.2: Tools - Add XY Data. The X field is longitude; Y field is latitude, and the Coordinate System was defined as Geographic, NAD83. Because of the format of the "gpstime" field, the default for ArcMap is to import this as a date/time field. Because I wanted this field to remain a text field, I edited the schema.ini file in the folder with the text file to define each attributes definition. I also made sure the DATE field imported as a text attribute to preserve the leading zero. I then used the data export (right-mouse click on the event theme, Data - Export Data) to save the event theme as a shapefile.
    schema.ini:
    [resnav_jd249.txt]
    Format=CSVDelimited
    ColNameHeader=True
    Col1=longitude Double
    Col2=latitude Double
    Col3=gpstime Text Width 8
    Col4=gpsdate Text Width 10
    Col5=depth_m float
    Col6=linename Text Width 11
    

    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:
    • resnav_jd249.txt

    Data sources produced in this process:

    • resgpspnts_jd249.shp

    Date: 2009 (process 13 of 13)
    Using ArcMap 9.2 added the attributes "gps_src' and "bathy_src" so that I could differentiate the source of each navigation fix and bathymetry value. On this particular day, all the navigational fixes came from the Lowrance system, while the bathymetry values came from the ship's gps/fathometer system.

    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:
    • resgpspnts_jd249.shp

    Data sources produced in this process:

    • resgpspnts_jd249.shp

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


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?

    The primary navigation system used was a Lowrance 480M with an LGC-2000 Global Positioning System (GPS) antenna. The antenna was located 7.9 meters forward of the anchor point for the resistivity streamer, and approximately 3 meters forward of the fathometer transducer. These offsets were not entered into the GPS system. Additionally, because of navigation and fathometers issues, periodically the ship's navigation system was used to supplement these data. The ship had a Differential GPS (DGPS) system with the antenna placed in the same location as the Lowrance antenna. The fathometer was located (hull-mounted) roughly directly below the antenna, so no horizontal offset. Because of the mixture of systems, the accuracy is on the order of 20 meters.

  3. How accurate are the heights or depths?

    All the bathymetric values from this day were collected by the ship's fathometer. This fathometer was hull mounted approximately midship, relatively close to the navigation antenna. The values are assumed to be accurate to within 1 meter.

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

    There is a navigational fix and fathometer reading for every reading of resistivity data. No temperature data was recorded on this day.

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

    No duplicate points are present. The navigational fixes and depth values were checked for valid values. Invalid data points were deleted. No other checks were performed.


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: 26-May-2009
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 13:08:07 2010