Lagrangian ocean surface drifter deployments off the National Park of American Samoa, Tutuila, American Samoa, 2015

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Frequently anticipated questions:


What does this data set describe?

Title:
Lagrangian ocean surface drifter deployments off the National Park of American Samoa, Tutuila, American Samoa, 2015
Abstract:
Satellite-tracked, DGPS-equipped Lagrangian surface-current drifter deployments were conducted over 12 weeks between 14 April and 7 July 2015 at various locations within and offshore of the National Park of American Samoa study area to track surface currents. The drifters internally logged their location every 1 minute, and they transmitted their positions to satellites every 5 minutes. A drogue was attached to the drifters at 1 m below sea level in order to track the currents at that depth.
Supplemental_Information:
Additional information about the field activities from which these data were derived are available online at:
http://cmgds.marine.usgs.gov/2015-601-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Logan, Joshua B., 2017, Lagrangian ocean surface drifter deployments off the National Park of American Samoa, Tutuila, American Samoa, 2015: data release DOI:10.5066/F7RN362H, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Rosenberger, Kurt J., and Storlazzi, Curt D., 2017, Data from coastal circulation and water-column properties in the National Park of American Samoa, February-July 2015: data release DOI:10.5066/F7RN362H, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -170.762114
    East_Bounding_Coordinate: -170.623177
    North_Bounding_Coordinate: -14.204308
    South_Bounding_Coordinate: -14.296368
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/58c9b834e4b0849ce97b4bd8?name=NPSADrifterPlot.jpg&allowOpen=true (JPEG)
    Plot of all deployments of drifter tracks
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 14-Apr-2015
    Ending_Date: 07-Jul-2015
    Currentness_Reference:
    ground condition at time data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: comma-delimited text
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (8910)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    ASCII Table
    Comma-delimited ascii table of time, position, distance and direction travelled, and speed of ocean Lagrangian drifter. (Source: Producer defined)
    DT_UTC
    Date and time referenced to Universal Coordinated Time (Source: Global Positioning System)
    Range of values
    Minimum:14-Apr-2015 00:00:00
    Maximum:07-Jul-2015 23:59:59
    Units:seconds
    Resolution:1
    DT_LCL
    Date and time referenced to Local Time (Source: Global Positioning System)
    Range of values
    Minimum:14-Apr-2015 00:00:00
    Maximum:07-Jul-2015 23:59:59
    Units:seconds
    Resolution:1
    LAT
    Latitude in decimal degrees (Source: Global Positioning System)
    Range of values
    Minimum:-14.285861
    Maximum:-14.191470
    Units:decimal degrees
    Resolution:0.000001
    LON
    Longitude in decimal degrees (Source: Global Positioning System)
    Range of values
    Minimum:-170.733699
    Maximum:-170.651163
    Units:decimal degrees
    Resolution:0.000001
    UTMX
    X-coordinate in Universal Transverse Mercator Projection, Zone 2 (Source: Global Positioning System)
    Range of values
    Minimum:8420640.8
    Maximum:8431075.6
    Units:Meters
    Resolution:0.1
    UTMY
    Y-coordinate in Universal Transverse Mercator Projection, Zone 2 (Source: Global Positioning System)
    Range of values
    Minimum:528725.1
    Maximum:537629.9
    Units:Meters
    Resolution:0.1
    UTMZONE
    UTM Zone for this latitude/longitude (Source: Global Positioning System)
    ValueDefinition
    UTM ZoneZone Number
    DIST_M
    Along-track distance travelled between point x and point x-1 (Source: Global Positioning System)
    Range of values
    Minimum:0
    Maximum:181.5
    Units:Meters
    Resolution:0.1
    AZIMUTH
    Azimuth of distance travelled between point x and point x-1 (Source: Global Positioning System)
    Range of values
    Minimum:0
    Maximum:360
    Units:Degrees
    Resolution:1
    VEL_MS
    Velocity of drifter between point x and point x-1 (Source: Global Positioning System)
    Range of values
    Minimum:0
    Maximum:2
    Units:Meters per second
    Resolution:0.1
    VEL_KTS
    Velocity of drifter between point x and point x-1 (Source: Global Positioning System)
    Range of values
    Minimum:0
    Maximum:4
    Units:Nautical miles per hour (knots)
    Resolution:0.1
    Entity_and_Attribute_Overview: The first line of the csv file is a header line.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Joshua B. Logan
  2. Who also contributed to the data set?
    Staff of the National Park of American Samoa contributed to the deployment of the drifters over the time period of deployments.
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA
    USA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

These drifter deployments were conducted as a part of a larger investigation into the circulation and transport along the coast off the National Park of American Samoa on the island of Tutuila, American Samoa.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 18-Jan-2017 (process 1 of 2)
    Data were imported into Matlab to parse the data from one data file into individual drifter deployments. Distance, azimuth and drifter velocity were calculated using the GPS fixes. Data sources used in this process:
    • derivation of speed
    Date: 07-May-2019 (process 2 of 2)
    Edited attribute resolution on two attributes to be numeric only (from "1 second" to "1"). Updated Point of Contact and Metadata Contact information. No data were changed. Person who carried out this activity:
    Susan A. Cochran
    Pacific Coastal and Marine Science Center
    Assistant Deputy Center Director
    2885 Mission Street
    Santa Cruz, CA
    USA

    831-460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Storlazzi, Curt D., Cheriton, Olivia M., Logan, Joshua B., and Clark, Timothy B., 2017, Coastal circulation and water-column properties in the National Park of American Samoa, February-July 2015.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Data were plotted in ARC/GIS to ensure that only data points that represent the period that each drifter was free-floating are included, and extraneous points were removed (such as points on land or on the research vessel).
  2. How accurate are the geographic locations?
    Horizontal positional accuracy provided by the manufacturer (Pacific Gyre) is +/- 10 meters
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    No formal logical accuracy tests were conducted.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
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 and National Park Service as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? This zip file (NPSADrifterCSVFiles_namedwithLCLStart.zip) contains 26 individual .csv files, one for each drifter deployment. The files names represent YYYY-MM-DD-HHMMSS (local time) and drifter number.
  3. What legal disclaimers am I supposed to read?
    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.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data can be viewed with any text editor software.

Who wrote the metadata?

Dates:
Last modified: 07-May-2019
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA
United States

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/pacific_islands/tutuila/NPSADrifter_metadata.faq.html>
Generated by mp version 2.9.49 on Fri Sep 13 15:01:12 2019