RES2DINV Format for Modified Continuous Resistivity Profile Data Collected in the Corsica River Estuary, Maryland on May 15 and May 16, 2007 on USGS Cruise 07005

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 50-m streamer with an 11 electrode array with electrodes spaced 5 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. The maximum depth below the water surface the streamer can reach is approximately ¼ the streamer length. So for the 50-m streamer, maximum depth is about 12.5 meters. 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. Lowrance indicates the speed of sound used by the system is 4800 feet/second. Both the temperature and depth information are recorded in the logged GPS file. There are instances where no depth or temperature information is recorded due to an equipment problem. 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.

The linearized STG and DEP files generated by AGI's Marine Log Manager software AGI SSAdmin MLM v 1.3.4.201 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 - no version number). Processed lines in this dataset include L12F1, L24F1, L24F2, L25F1, L26F1, L27F1 (parts 1 and 2), and L28F1. These line names are what the * refers to in the source used and source produced citations. A more complete description of all the processing involved prior to this point can be found in the metadata for the raw resistivity data and the processed resistivity data for the "fixed bathy" files available at https://pubs.usgs.gov/of/2010/1094/html/catalog.html.

Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Attempted to modify http to https where appropriate. Reordered the links in the identification section to have a landing page link as the first link. Updated the link to the field activity. Moved the minimal source information provided to make it the first process step. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.

Added keywords section with USGS persistent identifier as theme keyword.