Processed Continuous Resistivity Profile Collected in the Neuse River, April 19, 2004

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: John F. Bratton
Originator: VeeAnn A. Cross
Publication_Date: 2005
Title:
Processed Continuous Resistivity Profile Collected in the Neuse River, April 19, 2004
Online_Linkage:
<http://pubs.usgs.gov/of/2005/1306/data/2004/proc_resis/apr19_proc.zip>
Larger_Work_Citation:
Citation_Information:
Originator: VeeAnn A. Cross
Originator: John F. Bratton
Originator: Emile Bergeron
Originator: Jeff K. Meunier
Originator: John Crusius
Originator: Dirk Koopmans
Publication_Date: 2005
Title:
Continuous Resistivity Profiling Data from the Upper Neuse River Estuary, North Carolina, 2004-2005
Series_Information:
Series_Name: Open-File Report
Issue_Identification: 2005-1306
Publication_Information:
Publication_Place: Woods Hole Science Center, Woods Hole, MA
Publisher: U.S. Geological Survey, Coastal and Marine Geology Program
Online_Linkage: <http://pubs.usgs.gov/of/2005/1306>
Description:
Abstract:
The Neuse River Estuary in North Carolina is a broad, V-shaped water body located on the southwestern end of Pamlico Sound. This estuary suffers from severe eutrophication for which several water quality models have recently been developed to aid in the management of nutrient loading to the estuary. In an effort to help constrain model estimates of the fraction of nutrients delivered by direct ground-water discharge, continuous resistivity profile (CRP) measurements were made during the spring of 2004 and 2005. CRP is used to measure electrical resistivity of sediments, a property that is sensitive to difference in salinity of submarine ground water. The 2004 and 2005 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. CRP data enables the mapping of the extent and depth of the fresher ground water within the estuary.
Purpose:
To provide resistivity data as collected by the AGI SuperSting system and processed with EarthImager software.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 20040419
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -76.729717
East_Bounding_Coordinate: -76.713317
North_Bounding_Coordinate: 34.972333
South_Bounding_Coordinate: 34.966467
Keywords:
Theme:
Theme_Keyword_Thesaurus: General
Theme_Keyword: CMGP
Theme_Keyword: coastal
Theme_Keyword: Coastal and Marine Geology Program
Theme_Keyword: Continuous Resistivity Profiling
Theme_Keyword: CRP
Theme_Keyword: ground-water
Theme_Keyword: marine resistivity
Theme_Keyword: submarine ground-water
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: Woods Hole Science Center
Theme_Keyword: Open-File Report
Theme_Keyword: OF 2005-1306
Place:
Place_Keyword_Thesaurus: General
Place_Keyword: Neuse River
Place_Keyword: North America
Place_Keyword: North Carolina
Place_Keyword: Pamlico Sound
Place_Keyword: United States
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.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: John F. Bratton
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2254
Contact_Facsimile_Telephone: (508) 457-2310
Native_Data_Set_Environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.0.0.535
Data_Quality_Information:
Lineage:
Source_Information:
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 stainless steel electrode array with electrodes spaced 10 meters apart. 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.
Process_Step:
Process_Description:
The data were transferred from the logging computer via AGISSAdmin software. The data file available for this day is N2.*.
Process_Step:
Process_Description:
A section of the STG file was removed due to bad time stamps (between records 1913 and 1920). $GPRMC lines within the GPS file that had bad time stamps or were otherwise corrupt were also deleted.
Source_Used_Citation_Abbreviation: N2.stg and N2.gps
Source_Produced_Citation_Abbreviation: N2_mod.stg and N2_mod.gps
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
The data were merged with navigation and linearized using AGI's Marine Log Manager software.
Process_Step:
Process_Description:
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.
Source_Used_Citation_Abbreviation: N2_mod.stg
Source_Produced_Citation_Abbreviation: N2proc.stg, N2proc.dep
Process_Step:
Process_Description:
The DEP file was checked for anomalous bathymetry values and those lines in the file were deleted.
Source_Used_Citation_Abbreviation: N2proc.dep
Source_Produced_Citation_Abbreviation: N2proc_mod.dep
Process_Step:
Process_Description:
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. For this reason, the data were processed without a value supplied (in the folder def_wres), and with a value supplied (in the folder wres). The average water resistivity value was calculated based on YSI temperature and conductivity data readings during the survey.
Source_Used_Citation_Abbreviation: N2proc_mod.dep
Source_Produced_Citation_Abbreviation: N2proc_wres.dep
Process_Step:
Process_Description:
EarthImager version 1.9.0 was used to process the data files. The *.ini file accompanying the results contains the parameters used during the processing. These parameters include: minimum voltage: 0.02 minimum abs(V/I): 2E-5 max repeat error: 3% min apparent res: 0.03 max apparent res: 1000 max reciprocal error: 5% remove spikes smooth model inversion finite difference method Cholesky decomposition Dirichlet boundary condition thickness incremental factor: 1.1 depth factor: 1.1 number of iterations: 8 stop criteria: max RMS 3%, error reduction 5%, L2Norm CRP processing using a 65% overlap
Process_Step:
Process_Description:
The results of the processing are a JPEG image of the resistivity profile, and an XYZ file containing the distance along, depth, apparent resistivity (ohm-m). The first pass at processing (Trial1) used the default water resistivity value, while the second pass (Trial2) used the average water resistivity value in the DEP file. The JPEG file produced uses a color scale that is based on the data from this particular file. **Caution: The XYZ output filename does not contain the trial number, so the processing technique is a function of the folder it resides in.
Source_Produced_Citation_Abbreviation:
N2proc_AllInvRes.xyz, N2proc_trial1_InvResShort.jpg, N2proc_trial2_InvResShort.jpg
Process_Step:
Process_Description:
The XYZ output file was then loaded into Matlab, along with the depth information, to create a new JPEG image with the same color scale for all the data files. In this manner, the JPEG images can be compared directly. Care was taken to try to get the vertical and horizontal scales uniform as well, although this was not always possible due to Matlab limitations. These images reside in the Matlab images folder. Part of the filename (defwres vs. wres), as well as information within the image indicates if the default water resistivity (defwres) data file was used or an average water resistivity (wres) value.
Source_Used_Citation_Abbreviation: N2proc_AllInvRes.xyz
Source_Produced_Citation_Abbreviation: N2proc_defwres.jpg, N2proc_wres.jpg
Distribution_Information:
Resource_Description: Downloadable Data
Distribution_Liability:
These data were prepared by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Although all data published in this report have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and/or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials.
Metadata_Reference_Information:
Metadata_Date: 20050901
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
Metadata_Extensions:
Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>
Profile_Name: ESRI Metadata Profile
Generated by mp version 2.8.6 on Tue Sep 13 12:06:45 2005