HYPACK NAVIGATION: Text Files of the DGPS Navigation Logged with HYPACK Software on USGS Cruise 06018 from Sept. 6 to Sept. 8, 2006

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

Frequently-anticipated questions:

What does this data set describe?

Title:
HYPACK NAVIGATION: Text Files of the DGPS Navigation Logged with HYPACK Software on USGS Cruise 06018 from Sept. 6 to Sept. 8, 2006
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, HYPACK NAVIGATION: Text Files of the DGPS Navigation Logged with HYPACK Software on USGS Cruise 06018 from Sept. 6 to Sept. 8, 2006: 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: -76.856267
    East_Bounding_Coordinate: -76.310367
    North_Bounding_Coordinate: 38.295767
    South_Bounding_Coordinate: 37.946450

  3. What does it look like?

  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: text file

  6. How does the data set represent geographic features?

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

      This is a Point data set.

    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?

    Entity_and_Attribute_Overview:
    The times recorded in the navigation file are in UTC. Keywords and the information they provide are as follows:
    INF: General survey information filled in by the data technician. In this case, the information recorded the first two days of the survey (jd249 and jd250 folders) was from a previous cruise. The correct information was entered for the final survey day (jd251 folder).
    FIL: Raw format file.
    ELL: Ellipsoid information. The name of the ellipsoid followed by the semi-major axis in meters and the flattening ration.
    PRO: Project information record where TME indicates Transverse Mercator and the central meridian of -75 indicates UTM, zone 18.
    TND: Survey time and date in UTC.
    DEV 0: Indicates that the lines with device designation 0 are lines of Ashtech DGPS data.
    OFF: device offsets (none used during this data collection)
    EOH: end of header
    The remaining elements have similar information in the first 3 columns. The first column will indicate the data type, the second column will indicate the device that recorded the information (0 for Ashtech) and the third column is the time tag (seconds past midnight) that is also sometimes referred to as the latency. The remaining information on each line is specific to the data type.
    POS: Position of the ship - in this case the antenna location - in the format "POS dn t x y" where dn=device number; t=time tag (seconds past midnight); x=easting; y=northing. On this cruise these values are in UTM, Zone 18, WGS84.
    QUA: Position quality information in the format "QUA dn t n m h sat mode" where dn=device number; t=time tag (seconds past midnight); n=number of values to follow; m = 10 minus HDOP (horizontal dilution of precision); h=HDOP; sat=number of satellites; mode=GPS mode (NMEA 0183 standard values) where 2=Differential GPS fix.
    RAW: Position information in the format "RAW dn t n lat long alt utc" where dn=device number; t=time tag (seconds past midnight); n=number of values to follow; lat=raw latitude X 100; long=raw longitude X 100; alt=antenna altitude above ellipsoid (meters); utc=GPS time in the format HHMM.
    MSG: Message string in the format "MSG dn t message" where dn=device number; t=time tag (seconds past midnight); message is the message sent from the device. On this cruise, two different messages were sent from the DGPS: $GPGGA and $GPGLL. These will be defined later.
    FIX: not defined in the HYPACK manual
    The NMEA strings present in the HYPACK file are the $GPGGA and $GPGLL. These are defined as follows.
    $GPGGA is GPS fix data in the format "$GPGGA, t, lat, lath, long, longh, q, sat, h, a, M, alt, M, t2, refcheck" where t=time in UTC in the format hhmmss.ss; lat=latitude in the format ddmm.mmmmmm; lath= N or S indicating the latitude hemisphere; long=longitude in the format dddmm.mmmmmm; longh=E or W indicating the longitude hemisphere; q=fix quality where 2 is a DGPS fix; sat=number of satellites; h=Horizontal Dilution of Precision (HDOP); a=Antenna altitude above mean sea level (geoid); M= units of antenna altitude in meters; alt=height of geoid above WGS84 ellipsoid; M=units of geoidal height in meters; t2=time since last DGPS update; refcheck=DGPS reference station id and the checksum.
    $GPGLL is geographic position date in the format "$GPGLL, lat, lath, long, longh, t, vcheck" where lat=latitude in the format ddmm.mmmmmm; lath=N or S indicating the latitude hemisphere; long=longitude in the format dddmm.mmmmmm; longh=E or W indicating the longitude hemisphere; t=time in UTC in the format hhmmss.ss; vcheck=data valid and checksum.
    Entity_and_Attribute_Detail_Citation:
    The definitions of the HYPACK strings were acquired from the HYPACK software manual available from: <http://www.hypack.com/>. The definitions of the NMEA strings were obtained from: <http://home.mira.net/~gnb/gps/nmea.html>

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 these data is to provide the navigation as recorded by Ashtech Differential Global Positioning System (DGPS) with HYPACK software. This provides an archive of the original navigation as well as allowing others to reprocess the navigation for their purposes.

How was the data set created?

  1. From what previous works were the data drawn?

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

    Date: 2006 (process 1 of 1)
    A USB thumb drive was used to transfer the text navigation files from the computer running the HYPACK navigation software. The original HYPACK navigation files are stored in three separate directories indicating the acquisition Julian Day (jd249, jd250, jd251) which correspond to Sept. 6, 2006; Sept. 7, 2006; and Sept. 8, 2006 respectively. The filenames in each folder are in the format of linenumber_starttime.julianday. Since we weren't surveying any previously loaded lines, the "linenumber" is always 000. An example filename is 000_1211.249 which reflects line 000, start time 1211 and Julian day 249. The times in the filename reflect UTC (Coordinate Universal Time) times.

    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

  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 navigation receiver used was an Ashtech DGPS2. The accuracy of this system is better than 10 meters. The antenna was located 7.9 meters forward of the anchor point for the resistivity streamer and approximately 2 meters forward of the seismic transducer. This offset was not entered into the software.

  3. How accurate are the heights or depths?

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

    These files represent all the navigation recorded by the HYPACK software version 4.31.8.9 during USGS cruise 06018.

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

    These are the original files recorded by the HYPACK navigation software. No additional checks or corrections have been made to these files.

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?

    The user must have software capable of uncompressing the WinZip file.

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 13:07:07 2010