Ginger Barth Wayne E. Baldwin Robert S. Reece Sean S. Gulick William W. Danforth Florence L. Wong 20220825 vector digital data data release DOI: 10.5066/F7HM56HK Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/F7HM56HK https://www.sciencebase.gov/catalog/item/5605a22ae4b058f706e5152c Ginger Barth Wayne E. Baldwin Robert S. Reece Sean S. Gulick William W. Danforth Florence L. Wong 2022 data release DOI: 10.5066/F7HM56HK Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/F7HM56HK This shapefile contains center-beam depths for approximately 5804 trackline kilometers of Simrad EM122 multibeam-bathymetry data collected in the Gulf of Alaska during U.S. Geological Survey (USGS) cruise MGL1109 aboard the R/V Marcus G. Langseth. The depth values were extracted from gridded data which were reduced for position, elevation, orientation, water-column sound-speed, and refraction effects. In June 2011, the U.S. Geological Survey (USGS) conducted a research cruise in the Gulf of Alaska aboard the R/V Marcus G. Langseth (Lamont-Doherty Earth Observatory, Columbia University) as part of the U.S. Extended Continental Shelf Project. The mission focused primarily on obtaining geophysical data (multichannel and CHIRP seismic reflection, ocean bottom seismometry, multibeam bathymetry, sonobuoy, XBT and XCTD) for the purposes of determining geologic framework, crustal nature, and sediment thickness in support of delineating the U.S. Extended Continental Shelf under provisions contained in Article 76 of the United Nations Convention on the Law of the Sea (UNCLOS). Additional information about the USGS field activities from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=L0911GA https://cmgds.marine.usgs.gov/fan_info.php?fan=2011-034-FA Additional information about the Lamont-Doherty field activities from which these data were derived is available online at: https://www.rvdata.us/search/cruise/MGL1108 https://www.rvdata.us/search/cruise/MGL1109 Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology. This information is not intended for navigational purposes. 20110603 20110625 publication date Complete None planned -152.379177 -137.883352 57.711567 48.308887 ISO 19115 Topic Category environment geoscientificInformation oceans Data Categories for Marine Planning Bathymetry and Elevation Physical Habitats and Geomorphology USGS Thesaurus bathymetry multibeam sonar marine geophysics geospatial datasets Marine Realms Information Bank (MRIB) keywords marine geophysics multibeam echo sounder continental shelf None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC USGS Metadata Identifier USGS:5605a22ae4b058f706e5152c Geographic Names Information System (GNIS) Gulf of Alaska Bering Sea Kodiak Island Dutch Harbor NGA GEOnet Names Server (GNS) Baranof Fan Shirshov Ridge Kodiak Seamount Bowie Seamount Aleutian Trench Umnak Plateau Aleutian Basin Bowers Ridge None Surveyor Fan Extended Continental Shelf None USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator of the dataset and in products derived from these data. This information is not intended for navigation purposes. U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

2885 Mission Street

Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov https://www.sciencebase.gov/catalog/file/get/5605a22ae4b058f706e5152c?name=MGL1109bathy.JPG&allowOpen=true MGL1109 bathymetry, Gulf of Alaska JPEG Environment as of Metadata Creation: Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; ESRI ArcCatalog 10.2 (Build 3552) Service Pack [N/A] (Build [N/A]) David W. Caress Dale N. Chayes 2006 https://www3.mbari.org/data/mbsystem/html/mbsystem_home.html Kongsberg-Simrad EM122 Multibeam Echosounder was used with transmit (fore-aft) and receive (athwart ships) beam widths of 1 degree, with swaths of 3-4 times water depth in water depths between 50 and 6000 m. Depth accuracies not determined, however Kongsberg-Simrad state that the system is capable of depth accuracies approaching 0.2 percent of water depth. No formal logical accuracy tests were conducted Raw EM122 Multibeam Echosounder data collected during OBS operations were not used in the generation of this gridded dataset because OBS instruments were deployed along transects coincident with previously surveyed ship track. Upon inspection in CARIS during post-processing it was deemed appropriate to exclude the redundant data from the gridding process. Horizontal positioning of the vessel was determined using a Kongsberg Seapath 300 series integrated inertial motion and positioning system. Positioning is accurate to better than 5 meters (at 95 percent confidence) during all surveying. All positioning is referenced to the WGS84 Datum. No attempt was made to determine the accuracy of the system although recorded depths are typically within +/-10 m of the center-beam multibeam sounding. Multibeam bathymetry and backscatter data were collected using a 12 kHz Kongsberg Simrad EM-122 multibeam echosounder and SIS (v3.8.2) acquisition software. The system consists of two hull-mounted transducer arrays, a transmit unit (150 deg. x 1 deg.) located along the ship centerline, and a receive unit (1 deg. x 30 deg.) that is abaft and oriented athwart-ships. The transducer pod is tilted 4 degrees towards the bow to reduce noise from cavitation and bubbles. The system forms a swath of 288 beams that produce an across-track profile of 432 soundings. The SIS software processes range/angle data from each ping during acquisition, merging position, inertial-motion, and sound-velocity data to derive a solution for vessel motion and raybending, and calculate sounding depths and positions. Sound velocity information entered into SIS was obtained from the Applied Micro Systems Micro SV mounted on the transducer pod and 52 XBT profiles. XBT profiles were extended to 12 km depth with data generated by the unix program 'mblevitus', a module of the multibeam processing package MB-System (Caress and Chayes, 2006). Average water column salinity of 34.4 ppt was determined by extrapolating data from XCDT casts. Multibeam data were collected nearly continuously throughout the cruise, effectively mapping the seafloor along the course of the ship's track. Beam angle was set at 70 on each side throughout the program and swath widths were generally between 3 and 4 times water depth. SIS logged bathymetry and backscatter solutions to the Simrad '.all' format for archival purposes. 201106 CARIS processing for MGL1109: A new CARIS HIPS project (ver. 7.1) was created with projection information set to Universal Transverse Mercator (UTM) Zone 6N, WGS84. Each Simrad EM122 data file (*.all) was imported to the new CARIS project using the Import/Conversion Wizard. A 100 meter resolution Bathymetric and Statistical Error (BASE) Surface was created and new files were added to the surface each Julian day. With the addition of new files, the BASE surface was reviewed for any inconsistencies or data anomalies. Navigation was edited as needed using the navigation editor tool in CARIS. Filters were applied to each line including beam to beam slopes and across track angle. The CARIS "surface filter" was applied to the data using the two standard deviation option. Swath data were also edited manually to remove obviously outlying soundings. 201205 U.S. Geological Survey Wayne Baldwin Geologist mailing and physical address

384 Woods Hole Road

Woods Hole MA 02543-1598 USA 508-457-2226 wbaldwin@usgs.gov The 100 meter CARIS HIPS BASE surface for MGL1109 was exported from CARIS as a Bathymetric Attributed Grid (BAG) file. The resulting BAG file was used to import the surface into IVS3D DMagic as gridded data, then the surface was saved as a Fledermaus Digital Terrain Model in the IVS3D SD format. Finally, the Fledermaus ArcGIS module was used to export the surface directly to an ESRI Binary Grid. 201205 U.S. Geological Survey Wayne Baldwin Geologist mailing and physical address

384 Woods Hole Road

Woods Hole MA 02543 USA (508) 457-2226 (508) 457-2310 wbaldwin@usgs.gov Navigation information (Easting,Northing,Longitude,Latitude,UTC Time,Year-Julian Day,SIS Filename) were extracted from the CARIS HIPS database utilizing a Perl script that ran the CARIS command 'printfnav' on all edited EM122 data files. Unix 'cat' was used to concatenate the output nav files to a single file, 'grep' was used to extract only soundings flagged as accepted, then an 'awk' filter was used to extract records with unique navigation fixes, one per second. The resultant text file was used to create an ArcGIS point feature class (ArcMap, create feature class from XY table). 201205 U.S. Geological Survey Wayne Baldwin Geologist mailing and physical address

384 Woods Hole Road

Woods Hole MA 02543-1598 USA (508) 457-2226 wbaldwin@usgs.gov Version 1 of metadata compiled by wbaldwain@usgs.gov 201205 The navigation text file created in the previous step was used to create an ArcGIS point feature class (ArcMap, create feature class from XY table). The navigation point feature class and the ESRI binary grid 'MGL1109_bathy' were used as the point and raster inputs for the ArcGIS Spatial Analyst tool 'Extract values to points', with the interpolate values at point locations option selected. The resultant point shapefile containing "Easting, Northing, Longitude, Latitude, UTC Time, Year-Julian Day, SIS Filename, Depth (meters)" was exported to ASCII text. 201205 U.S. Geological Survey Wayne Baldwin Geologist mailing and physical address

384 Woods Hole Road

Woods Hole MA 02543-1598 USA (508) 457-2226 wbaldwin@usgs.gov A trackline shapefile strung through the original centerdepth file (MGL1109_EM122centerdepth.txt) had a loop that was not present in the 1-minute shipboard navigation fixes. The original file appeared to have been sorted on the FILE attribute, which has Julian day and time embedded, but some entries did not match the YRJD and UTC attributes and were, consequently, not time sequential. The text file was converted to a point shapefile with a new attribute "jd_hhmmss" combining YRJD and UTC that was used to re-sort the centerdepth file. The "sequence" attribute is the record number after the re-sort. The shapefile attributes are EAST,NORTH,LON,LAT,UTC,YRJD,FILE,EM122depth,jd_hhmmss,sequence. (fwong@usgs.gov) 201411 Metadata was modified to bring up to current USGS PCMSC standards. Point of Contact and Metadata Contact information was updated. Keywords were added and refined. Cross Reference citation added. Details about different Network Resource Name links was given in the Access Instructions section. Minor typos were corrected. No data information was changed. 20220818 Susan A Cochran U.S. Geological Survey, Pacific Coastal and Marine Science Center Geologist mailing and physical

2885 Mission St.

Santa Cruz CA 95060 United States 831-460-7545 scochran@usgs.gov Point point 1997840 0.0196893509 0.0324373614 Decimal seconds D_WGS_1984 WGS_1984 6378137.0 298.257223563 Attribute Table Table containing attribute information associated with the data set. Producer defined EAST x-coordinate, UTM Zone 6N Producer defined 169222.94 1175654.93 meters NORTH y-coordinate, UTM Zone 6N Producer defined 5390933.7 6407818.35 meters LON longitude Producer defined -152.378794 -137.883352 degrees LAT latitude Producer defined 48.308887 57.711015 degrees UTC time UTC Producer defined Time formatted as HH:MM:SS, where HH = hour (0-23), MM = minute (0-59), SS = second to 3 decimal places (0-59.999). YRJD year and day of the year Producer defined Year and day of the year (1-365). FILE filename Producer defined swath filename EM122depth depth Producer defined -5380.43 -51.4 meters jd_hhmmss julian day and time for labels Producer defined day and time for labels sequence sorted record sequence number Producer defined record number The entity and attribute information provided here describes the tabular data associated with the data set. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the data set. The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information. U.S. Geological Survey - ScienceBase mailing and physical

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov These data are available in shapefile format, along with accessory files and CSDGM FGDC-compliant metadata. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. shapefile 100 https://www.sciencebase.gov/catalog/file/get/5605a22ae4b058f706e5152c https://www.sciencebase.gov/catalog/item/5605a22ae4b058f706e5152c https://doi.org/10.5066/F7HM56HK Data can be downloaded using the Network Resource Links. The first link is a direct link to download a zipped file with the data and metadata. The second link is to the page containing the data. The third link is to the publication landing page. None 20220825 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

2885 Mission Street

Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998