RES2DINV Format Continuous Resistivity Profiles from Cape Cod National Seashore, Feb. 28, 2006

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Frequently-anticipated questions:

What does this data set describe?

Title:
RES2DINV Format Continuous Resistivity Profiles from Cape Cod National Seashore, Feb. 28, 2006
Abstract:
Continuous resistivity profiling (CRP) surveys were conducted at Cape Cod National Seashore in 2004 and 2006 in order to test hypotheses about groundwater flow under and into estuaries and the Atlantic Ocean. Coastal resource managers here and elsewhere are concerned about nutrients that are entering coastal waters via submarine groundwater discharge, which are contributing to eutrophication and harmful algal blooms. CRP is used to measure electrical resistivity of sediments, a property that is sensitive to differences in salinity of submarine ground water. The 2004 and 2006 surveys used floating resistivity streamers of 100 m and 50 m respectively. The depth penetration of the streamers is approximately 20% of the streamer length which translates to approximately 20-25 m with the 100 m streamer and 12-14 m with the 50 m streamer. These data were processed using AGI's EarthImager 2D software.
  1. How should this data set be cited?

    Bratton, John F. , 2008, RES2DINV Format Continuous Resistivity Profiles from Cape Cod National Seashore, Feb. 28, 2006: Open-File Report 2006-1169, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A. , Bratton, John F. , Crusius, John, Colman, John A. , and McCobb, Timothy D. , 2008, Submarine Hydrogeological Data from Cape Cod National Seashore: Open-File Report 2006-1169, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -69.973172
    East_Bounding_Coordinate: -69.945350
    North_Bounding_Coordinate: 41.836933
    South_Bounding_Coordinate: 41.820967

  3. What does it look like?

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

    Calendar_Date: 28-Feb-2006
    Currentness_Reference: ground condition

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

  6. How does the data set represent geographic features?

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

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

  7. How does the data set describe geographic features?

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
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    508-548-8700 x2254 (voice)
    508-457-2210 (FAX)
    jbratton@usgs.gov

Why was the data set created?

To provide the linearized raw resistivity data collected by the AGI SuperSting system in the RES2DINV format.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Source_Contribution:
    These data were acquired with an AGI SuperSting Marine system that is described at the website: www.agiusa.com/marinesystem.shtml. The particular system used for this acquisition was an 11 electrode array with electrodes spaced 5 meters apart. The potential electrodes are made of graphite, with the remaining electrodes 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 potentials 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 *.gps file. The STG file contains the resistivity data, while the GPS file contains the navigation information including bathymetry. GPS and bathymetry data acquired with a Lowrance system.

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

    Date: 2006 (process 1 of 10)
    The data were transferred from the logging computer via AGISSAdmin software. The data files available for this day are l1*, l2*, l3*, l4*, l5*, l6*, l8*, l9*, l10*, l11*, l12*, l13*, l14*, and l15*. ***Of note, on lines 1 and 2, during acquisition the distance between the cable connection point and the first electrode was entered as 10 meters instead of -10 meters. This can be adjusted when reading the data into Marine Log Manager for linearization.

    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 2 of 10)
    $GPRMC lines with the GPS file that had bad time stamps or were otherwise corrupt were deleted.

    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 3 of 10)
    The resistivity data were merged with the navigation data and linearized using AGI's Marine Log Manager software. (Note that the Marine Log Manager version is different than the software version of the AGISSAdmin software of which it is a part - although shipped together, the software is developed separately). In some instances, only a portion of the line was exported for processing. In particular, turns are removed before processing. (AGISSAdmin version 1.33.182). ***Note. When reading in l1 and l2, the GPS offset needs to be set to 10 to account for an incorrect acquisition paramger indicating the distance between the cable connection point and the first electrode.

    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 file was then exported to a new STG file, and accompanying DEP file. The DEP file contains the distance along line and bathymetry values.

    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)
    In most cases, nearshore values were very important. For that reason, the whole linearized STG file was selected for export. This applied in the following lines: l1, l2, l4, l5, l6, l9, l11, l12 and l14. The way the Marine Log Manager software works, the first value exported is where at least one of the electrodes has a known navigational fix. But the rest of the streamer electrodes at this position have a negative distance along line. When this export option is chosen, no DEP file is output. In order to create a DEP file, a second export file is needed. This one selects only positive electrode positions for export.

    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 6 of 10)
    The linearized STG file with negative values is processed with EarthImager version 2.01 in order to determine the most negative position (available from the final XYZ output file). Once this is done, I can create a navigation fix for that negative distance along line. Based on the trackline created from the GPS data, I run an ArcView 3.3 avenue script (extendline.ave) which uses a straight-line tow path assumption of the first 2 points to create an additional point at the negative distance input. Essentially I extend the line at the start of the line.

    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 7 of 10)
    With this new point I can modify the DEP file generated by the positive only electrode position export. I add in the negative distance along, as well as all the supplemental information, including the header information describing the latitude and longitude position of the start of line. So now I have a linearized STG file, as well as the accompanying DEP file for those files with negative distances along line.

    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 8 of 10)
    The DEP file was checked for anomalous bathymetry values, or duplicated distance along values, and those lines in the file were deleted.

    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 9 of 10)
    EarthImager software does not require that a default resistivity value for the water column be supplied in the DEP file. If one is not supplied, then it calculates a value based on the first electrode pair. On this survey, an instrument was used periodically to measure water conductivity. This value was converted to appropriate resistivity units and added to the DEP file. A value of 0.2 was used in all the files.

    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 10 of 10)
    The STG and DEP file were converted to a format suitable for the RES2DINV processing software. The conversion was accomplished by a Visual Basic 6 program written at the USGS office in Woods Hole (AGI2res2d.exe).

    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

  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?

  3. How accurate are the heights or depths?

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

    Only those lines with valid resistivity data are represented here.

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

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 U.S. Geological Survey must be referenced as the originator of the dataset in any future products or research derived from these data.

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

    John F. Bratton
    U.S. Geological Survey
    384 Woods Hole Rd.
    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?

    These data are availabe in a format compatible with the RES2DINV resistivity inversion software. The user must have software capable of reading this format in order to process the data.

Who wrote the metadata?

Dates:
Last modified: 25-Feb-2008
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 2.8.6 on Tue Jul 08 11:35:34 2008