All the data were handled in the same manner. Inconsistencies exist in the filenaming convention for individual seismic data collection lines. Because the filenames reflect the original data file names acquired in the field, they were left alone.
No data were acquired on the following dates: 6/8/2006, 6/10/2006 6/12/2006, 6/13/2006, 6/15/2006, 6/16/2006, 6/17/2006, 6/18/2006, 6/19/2006, 6/20/2006. These dates correspond to Julian days 159, 161, 163, 164, 166, 167, 168, 169, 170, and 171 respectively.
In addition, lines for which no valid seismic data were available, or extremely short lines, were deleted. Some lines acquired seismic data, but little or no navigation. These lines are also excluded. One line was re-run, so the original problematic line was excluded. The list of collected seismic lines excluded from this and subsequent datasets is as follows: Julian day 155 - apalachicola000 (rerun), apalachicola020 (too short), apalachicola027 (insufficient navigation). Julian day 160 - day160001 (insufficient navigation). Julian day 165 - day165001 (too short). Julian day 172 - JD172010 (too short), JD172014 (too short), JD172025 (too short). Julian day 173 - JD173009 (too short). Julian day 174 - JD174010 (too short).
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: unpublished material
Title: Data acquisition
Type_of_Source_Media: digital files
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20060603
Ending_Date: 20060627
Source_Currentness_Reference: ground condition of data acquisition
Source_Citation_Abbreviation: none
Source_Contribution:
The data were collected using the USGS WHCMSC Autonomous Surface Vessel (ASV) IRIS. This system is designed to operate in shallow water (1-5 meters). IRIS is a catamaran platform 3 meters in length, 1.2 meters in width, and approximately 118 kilograms. The vehicle is operated remotely through a wireless modem network enabling real-time monitoring of data acquisition. The system is navigated using a ZXW RTK augmented GPS system enclosed on a platform in the middle of the catamaran. An enclosed onboard micro-processor-based motor controller provides signals for speed and steering to hull-mounted brushless direct-current thrusters. A center-mounted keel encloses the chirp dual-frequency (100/400 kHz model 4200 EdgeTech) sidescan-sonar transducers and EdgeTech 424 chirp seismic-reflection hydrophones. Mounted in the port hull are the EdgeTech 424 chirp seismic-reflection transducer and a single-beam 235 kHz echosounder. A Sony IP based wireless video camera is installed on the mast of IRIS for the purpose of obstacle avoidance. An onboard Fluxgate magnetometer provides heading, heave, pitch, and roll. IRIS is powered by 2-4 24-volt NiMH batteries located in each hull and has an approximate run-time of five hours at 4 knots.
Process_Step:
Process_Description:
The seismic data were acquired with an EdgeTech SB-424 sub-bottom profiler and recorded in JSF format using JSTAR, EdgeTech's acquisition software. The research effort within Apalachicola Bay represented the first use of IRIS in full survey mode. As such, the system needed to be 'rung-out' during the first several days of surveying. A file naming convention developed over the first few days of surveying and acquisition settings (hardware and software) were modified several times until standardized settings could be established for Apalachicola Bay. Initial trouble-shooting dealt with several issues including a variation in the field in which navigation was stored within the JSF header and in the resolution of the navigation (seconds of arc vs. minutes of arc). Correcting these issues required re-running particular files though EdgeTech's DISCOVER software and saving new JSF files. Files that were saved through DISCOVER are signified by a 'yes' in the 'discover' field within the shapefile. A 'no' within the 'discover' field indicates that the JSF file was correct in its original format; re-running through DISCOVER was not required. The JSF files were then converted to SEG-Y format using jsf2segy, a C-program written by Tom O'Brien at the Woods Hole Coastal and Marine Science Center, U.S. Geological Survey.
Process_Date: 2006
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Tom O'Brien
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geophysical Systems Expert
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 x2246
Contact_Facsimile_Telephone: 5084572310
Process_Step:
Process_Description:
These original SEG-Y files are in IEEE format and were converted to IBM floating point using SIOSEIS. In addition to this conversion, the shot numbers have been renumbered in order to start at one.
Process_Date: 2006
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: David S. Foster
Contact_Organization: U.S. Geological Survey
Contact_Position: 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 x2271
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: dfoster@usgs.gov
Process_Step:
Process_Description:
A csh script utilized Seismic Unix (v. 4.0) to extract all of the unique navigation points from the SEG-Y header within the seismic data. These values were written to a comma-delimited text file. In addition to extracting the navigation, the csh script was used to generate JPEG images of each seismic profile. Due to modifications to acquisition parameters during the initial days of surveying, the format in which navigation was stored in the SEG-Y headers varies: navigation is stored in either decimal arc seconds (0.01) or decimal arc minutes (0.0001). In order to properly extract and convert navigation to latitude/longitude divisors of 360000 and 600000 were used for decimal arc seconds and decimal arc minutes, respectively.
Prior to JD172, the acquisition system did not consistently record longitude as a negative value (western hemisphere). Thus, either 600000 or -600000 was used to convert arc minutes to longitude based on whether the acquisition software recorded negative or positive longitude values. The divisors necessary for proper navigation extraction are contained in the attribute field "divisors" and are in the format "longitude divisor/ latitude divisor". This process step and all subsequent process steps were performed by the same person - VeeAnn A. Cross.
Process_Date: 2006
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 individual comma-delimited text files were then concatenated to generate a single navigation text file. This file was edited to remove invalid positions (usually latitude and longitude values of 0). In addition, calendar year and Julian day values were edited as necessary in order to reflect appropriate values. Finally, a header was added to the navigation text file in order to describe each column of data.
Process_Date: 2006
Process_Step:
Process_Description:
The navigation text file was added to ArcMap 9.1 as an XY point event layer and converted to a point shapefile.
Process_Date: 2006
Process_Step:
Process_Description:
The attribute "lmarkname" was added to the shapefile. This attribute will be used as the unique line name when loading the data into Landmark SeisWorks software. Seismic lines containing circles or turns were broken into multiple segments and assigned a unique line name by appending an "a" or "b" etc. to the line name. Landmark can load a portion of a SEGY file by loading the line segment that corresponds to the shot point navigation. (i.e. Splitting a SEGY file into segments is unnecessary, only the navigation needs to be split). During the initial days of surveying, the seismic acquisition system simultaneously recorded multiple files per survey line, creating some data redundancies. These overlapping portions of the survey line do not have a value entered in the "lmarkname" attribute
Process_Date: 2007
Process_Step:
Process_Description:
All records that do not have a blank in the "lmarkname" attribute are selected and saved to a new point shapefile that will be used to load SEG-Y data into Landmark software.
Source_Used_Citation_Abbreviation: allasvpntnav_mod.shp
Process_Date: 2007
Source_Produced_Citation_Abbreviation: allasv4landmark.shp
Process_Step:
Process_Description:
This point layer was then converted to a polyline shapefile using the Points to Lines v2 script in VAC Extras v. 1.98 (a collection of tools used in the USGS Woods Hole Coastal and Marine Science Center). The lines are based on a unique identifier in the point attribute table (lmarkname). The first occurrence of the following attributes is carried over: filename, shot, year, jday, seistime.
Source_Used_Citation_Abbreviation: allasv4landmark.shp
Process_Date: 2007
Source_Produced_Citation_Abbreviation: allasv4landmark_lns.shp
Process_Step:
Process_Description:
The attributes "discover" and "divisors" were added to the attribute table. These attributes help to discern how the data was handled immediately after acquisition. In particular, the "divisors" attribute will be beneficial to anyone working with the SEG-Y data and will be needed to extract the navigation from the headers.
Source_Used_Citation_Abbreviation: allasv4landmark_lns.shp
Process_Date: 2007
Source_Produced_Citation_Abbreviation: allasv4landmark_lns.shp
Process_Step:
Process_Description:
The polyline shapefile was converted to a route using ArcMap 9.2 - ArcToolbox - Linear referencing - Create Routes. Input: allasv4landmark_lns; route identifier: lmarkname; output: asvlmark_route.shp; rest of the parameters at the defaults ( measure source - length; coordinate priority - upper_left; measure factor - 1; measure offset - 0; ignore spatial gaps - checked; build index - checked).
Process_Date: 2007
Process_Step:
Process_Description:
The original point navigation will be used to calibrate the polylines based on shot number. However, before this can be done, any points with duplicate location need to be removed. Within ArcMap 9.2, using XTools Pro v. 5.2 - Table operations - Find Duplicates set the output to allasv_nodupes.shp. Other parameters: add feature to current map, create spatial index, compare by shape - check box to remove duplicates; index field name - index. Deselect the option to add ID field of the source feature. After this was done, a comparison showed the original shapefile had 123157 points and the new one had 122950 points.
Process_Date: 2008
Process_Step:
Process_Description:
Sort the new shapefile using VACExtras v 2.0, VAC Extras - Feat Conv - Table Sort. Primary sort is lmarkname in ascending order, secondary sort is shot in ascending order. Output: all asv_nodupes_sort.shp.
Process_Date: 2008
Process_Step:
Process_Description:
Now I need to look for loop back sections in the seismic tracklines. The easiest way to do this was to find problems with a calibrated route, so within ArcMap 9.2 calibrate the route using ArcToolbox - Linear Referencing - Calibrate Routes. Input: asvlmark_route; route identifier: lmarkname; input points: allasv_nodupes; point identifier: lmarkname; measure field: shot; output route feature class:asvlmark_route_Calibratedtmp.shp. Rest of the fields were left at their default values. Once the route was calibrated, create the end hatches for the routes using the shapefile Properties - Hatches - Add Hatch Definition. Add end hatch definition set the hatch to a marker, tolerance 0 and lateral offset 0. With the hatches displayed, the point shapefile can be edited to sort out the bad portions.
Process_Date: 2008
Process_Step:
Process_Description:
Taking the cleaned point shapefile, generate a new polyline from these points. Using VACExtras 2.0 - VAC Extras - Feat Conv - Points to Line v2. The unique line identifier: lmarkname. Fields to transfer first occurrence: filename, shot, year, jday, seistime, discover, divisors. Output to asv_lines.shp.
Process_Date: 2008
Process_Step:
Process_Description:
Convert the line to a route using ArcMap 9.2 - ArcToolbox - Linear referencing - Create Routes. Input: asv_lines; route identifier: lmarkname; output: asv_lines_Routes.shp. Rest of the parameters left to default.
Process_Date: 2008
Process_Step:
Process_Description:
Calibrate the route using ArcMap 9.2 - Linear Referencing - Calibrate Routes. Input: asv_lines_Routes; route identifier: lmarkname; input points: allasv_nodupes_sort; point identifier: lmarkname; measure field: shot; output route feature class: asv_lines_Calibrated.shp. Rest of the parameters left at the defaults.
Process_Date: 2008
Process_Step:
Process_Description:
Add the following attributes to the calibrated shapefile: year, jday, discover, divisors, orig_fname. In order to populate these fields, join asv_lines_Calibrated to asv_lines with the join field set to lmarkname in both shapefiles. Once the files are joined, field calculator is used to copy the attribute values form the asv_lines attributes to the asv_lines_Calibrated attributes.
Process_Date: 2008
Process_Step:
Process_Description:
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.). The source information was incomplete and had to be modified to meet the standard. 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.
Process_Date: 20160629
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
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
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description: USGS Thesaurus keywords added to the keyword section.
Process_Date: 20180720
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
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: Crossref DOI link was added as the first link in the metadata.
Process_Date: 20191118
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
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:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20200908
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
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
