Shot point navigation at even 500 shot intervals for Knudsen 3202 seismic-reflection data collected by the USGS within Red Brook Harbor, MA, 2009 (RB_SeismicShot_500)

A C-shell script was executed that called on Seismic Unix (version 4.1) to read the SEG-Y files, write a Seismic Unix file, and extract SEG-Y trace header information, including shot number, longitude, latitude, year, Julian day, and time of day (UTC) to ASCII text files for each survey line. Files for data collected during Julian days 271-282, 288, and 294 were filtered using AWK (no version) to save records for the first and last shots, and shots at unique longitude/latitude positions in between. No navigation was recorded to the SEG-Y trace headers of all lines collected during Julian days 287 and 295, and portions of days 272 (l18f1_001) and 296 (l183f1_001 - l190f1_010), so separately logged 1 Hz DGPS ASCII navigation needed to be merged with the remaining information extracted from the trace headers. This was accomplished using an alternate AWK filter to save shot records for the first and last shots, the first shot recorded at each second, and shots numbers evenly divisible by 500. The VIM (version 7.2.108) text editor was then used to create a new field in each navigation and trace header text file that combined Julian day and UTC time. Finally, using the newly created field as the 'join' field, the unix JOIN (no version) command was used to merge coordinates from the navigation text file with corresponding shot records in each trace header file based on this Julian day time field. Geographic coordinates (WGS84) were converted to UTM zone 19 coordinates (WGS84) using Proj (version 4.6.0), and added to the text files in two new columns. VIM was used to add three additional columns to the text files containing the Woods Hole Coastal and Marine Science Center field activity number (SURVEYID), the device used to record the data (DEVICEID), and the vessel used for the survey (VEHICLEID).

An additional AWK filter was applied to each file created in the previous step to extract trace header records containing the first and last shots, and shots evenly divisible by 500 for each survey line. A 500 shot interval was chosen because it corresponds to the annotation interval provided along the top of the seismic-reflection profile JPEG images, which are included in the 'GIS\hyperlink_images\seisimage' directory.

Text files containing even 500 shot interval records were concatenated into a comma-delimited text file, then imported into ArcMap (version 9.2) using 'Add XY data' and saved as points (Geographic, WGS84) in the ESRI shapefile format ('RB_SeismicShot_500.shp').

Edits to the metadata were made to fix any errors that MP v 2.9.32 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.). Fixed URL in abstract. The source information was incomplete and had to be modified to meet the standard. 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.