CTD (conductivity-temperature-depth) data collected on Stellwagen Bank during U.S. Geological Survey field activity 2017-030-FA, aboard the R/V Auk, May 18-23, 2017

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Frequently anticipated questions:


What does this data set describe?

Title:
CTD (conductivity-temperature-depth) data collected on Stellwagen Bank during U.S. Geological Survey field activity 2017-030-FA, aboard the R/V Auk, May 18-23, 2017
Abstract:
This field activity is part of the effort to map geologic substrates of the Stellwagen Bank National Marine Sanctuary region off Boston, Massachusetts. The overall goal is to develop high-resolution (1:25,000) interpretive maps, based on multibeam sonar data and seabed sampling, showing surficial geology and seabed sediment dynamics. This cruise was conducted in collaboration with the Stellwagen Bank National Marine Sanctuary, and the data collected will aid research on the ecology of fish and invertebrate species that inhabit the region. The Sanctuary's research vessel, R/V Auk, visited 50 locations on Stellwagen Bank at which a customized Van Veen grab sampler (SEABOSS) equipped with a video camera and a CTD was deployed in drift mode to collect sediment for grain-size analysis, video imagery of the seabed, and measurements of water column properties.
Supplemental_Information:
Additional information regarding the field activity can be obtained from https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-030-FA.
  1. How might this data set be cited?
    Valentine, Page C., 2019, CTD (conductivity-temperature-depth) data collected on Stellwagen Bank during U.S. Geological Survey field activity 2017-030-FA, aboard the R/V Auk, May 18-23, 2017: data release DOI:10.5066/P94GOZ7C, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Valentine, Page C., and Cross, VeeAnn A., 2019, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in May 2017, U.S. Geological Survey Field Activity 2017-030-FA: data release DOI:10.5066/P94GOZ7C, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2019, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in May 2017, U.S. Geological Survey Field Activity 2017-030-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P94GOZ7C.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.458560
    East_Bounding_Coordinate: -70.134090
    North_Bounding_Coordinate: 42.420730
    South_Bounding_Coordinate: 42.171150
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 18-May-2017
    Ending_Date: 23-May-2017
    Currentness_Reference:
    ground condition when data were collected. Actual dates of collection May 18, 19, and 23, 2017
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: profile - water column
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
    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 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: local surface
      Depth_Resolution: 0.001
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Implicit coordinate
  7. How does the data set describe geographic features?
    Sea-Bird CTD
    The data from each station is included in an ASCII text file with an 11-row header that gives the station number and the output format of the data - what information is in each column. The remaining rows (starting at row 12) are columns of measured values that are space-delimited, and which correspond to the columns listed in the header. (Source: Sea-Bird Electronics)
    salt water depth, meter (0.000)
    Calculated value involving pressure, water density and compressibility as well as the strength of the local gravity field. Units are meters. (Source: Sea-Bird Electronics) Although this is a numeric value, the data value range for the dataset has not been evaluated.
    water temperature (standard ITS-90), deg C (0.0000)
    Temperature directly measured by the temperature-sensing instrument (thermistor). Units are degrees Celsius. (Source: Sea-Bird Electronics) Although this is a numeric value, the data value range for the dataset has not been evaluated.
    salinity, practical salinity units (PSU) (0.0000)
    Calculated value derived from the measured properties (conductivity, temperature and pressure) of the instrument. Units are practical salinity units. (Source: Sea-Bird Electronics) Although this is a numeric value, the data value range for the dataset has not been evaluated.
    water density, sigma-t, kilograms per cubic meter (0.0000)
    Calculated value derived from the measured properties (conductivity, temperature and pressure) of the instrument. Units are kilograms per cubic meter. (Source: Sea-Bird Electronics) Although this is a numeric value, the data value range for the dataset has not been evaluated.
    fluorescence, milligrams per cubic meter (0.0000)
    Fluorescence is a measurement of chlorophyll A concentration in a volume of seawater. Units are milligrams per cubic meter. (Source: Sea-Bird Electronics) Although this is a numeric value, the data value range for the dataset has not been evaluated.
    turbidity, nephelometric turbidity units (NTU) (0.0000)
    Turbidity is a measurement of particles in a volume of seawater. Units are nephelometric turbidity units. (Source: Sea-Bird Electronics) Although this is a numeric value, the data value range for the dataset has not been evaluated.
    if data flagged, indicates error in data collection
    System method of indicating erroneous or bad data. (Source: Sea-Bird Electronics) A value other than zero indicates an error in data collection
    Entity_and_Attribute_Overview:
    The following is a sample header and a few rows of the data:
    
    Sta 4579
    Output data format
    Column 1, salt water depth, meter (0.000)
    Column 2, water temperature (standard ITS-90), deg C (0.0000)
    Column 3, salinity, practical salinity units (PSU) (0.0000)
    Column 4, water density, sigma-t, kilograms per cubic meter (0.0000)
    Column 5, fluorescence, milligrams per cubic meter (0.0000)
    Column 6, turbidity, nephelometric turbidity units (NTU) (0.0000)
    Column 7, if data flagged, indicates error in data collection
    -0.196    21.2059     0.0000    -2.0511    -0.0449    -0.0084  0.000e+00
    -0.198    21.2044     0.0000    -2.0508    -0.0403     0.1717  0.000e+00
    -0.198    21.2032     0.0000    -2.0505     0.0299     0.0221  0.000e+00
    -0.199    21.2022     0.0000    -2.0503     0.0116     0.0500  0.000e+00
    -0.199    21.1997     0.0000    -2.0498    -0.0052     0.0545  0.000e+00
    -0.199    21.1985     0.0000    -2.0495    -0.0090    -0.0076  0.000e+00
    -0.199    21.1982     0.0000    -2.0494    -0.0006     0.0099  0.000e+00
    
    
    If visible in the sample above, the presence of the ">" character is for formatting the metadata only. That character does not actually occur in the data.
    The zeros associated with each column definition indicate the number of decimal places of the recorded values.
    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)
    • Page C. Valentine
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Page C. Valentine
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov

Why was the data set created?

These data are collected to map the seasonal temperature, salinity, density, fluorescence (chlorophyll A), and turbidity configuration of the water column which affect the distribution and availability of plankton and the distribution of fish and invertebrate species.

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: 2017 (process 1 of 3)
    These data were collected with a Sea-Bird CTD (conductivity, temperature, depth) instrument - a SBE19plusV2 SeaCAT Profiler CTD. This instrument was deployed on the USGS SEABed Observation and Sampling System (SEABOSS). See the cross-references for additional information on this system. The SEABOSS is an instrument developed by the USGS to collect samples and video and photographic images of the seabed to aid in the interpretation of seabed sonar imagery. The CTD is mounted horizontally on the SEABOSS frame and its maximum depth is approximately 1 meter above the seabed. The specifications for the CTD instrument are as follows:
    
    
    SBE19plusV2, serial number 01906617 manufactured by Sea-Bird Electronics, Inc.
    Firmware version: 2.2c
    Firmware date: 7 December 2009
    Manufactured date: 29 July 2010
    Software version: 2.3.0
    
    
    Internal sensors:
    main temperature, serial number 01906617
    main conductivity, serial number 01906617
    main pressure, type, strain, serial number 3161799
    
    
    External sensors from WET Labs:
    ECO-FLNTURT CHL, serial number FLNTURT-1798; WET Labs fluorometer, ECO-AFL/FL
    ECO-FLNTURT TURB, serial number FLNTURT-1798; WET Labs turbidity meter, ECO-NTU
    
    Configuration:
    Instrument battery operated; not connected to a conducting cable
    Profile mode: sampling rate 4 per second, averaged to provide each data point
    CTD deployed on the USGS SEABed Observation and Sampling System (SEABOSS)
    
    Data archive:
    All data; downcast, drift, and upcast 
    
    
    The temperature (degrees C) sensor has the following specifications:
    measurement range -5 to +35 degrees C; initial accuracy +-0.005; resolution 0.0001; 
    
    
    The conductivity (S/m) has the following specifications:
    
    
    measurement range 0 to 9 S/m; initial accuracy +- 0.0005; resolution varies: 0.00005 (most oceanic water; resolves 0.4 ppm in salinity) 0.00007 (high salinity water; resolves 0.4 ppm in salinity) 0.00001 (fresh water; resolves 0.1 ppm in salinity)
    
    
    The strain gauge pressure:
    
    
    measurement range 0 to full scale range: 20/100/350/600/1000/2000/3500/7000; initial accuracy +- 0.1% of full scale range; resolution 0.002% of full scale range.
    
    
    The turbidity sensor:
    wavelength 700 nm; sensitivity 0.01 NTU, rant 0-25 NTU
    
    
    Fluorescence sensor:
    Chlorophyll-a 470 nm EX/695 nm EM; sensitivity 0.2 micro-g/l; range 0-125 micro-g/l Chl
    
    Person who carried out this activity:
    U.S. Geological Survey
    Attn: Page C. Valentine
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov
    Date: 2017 (process 2 of 3)
    The Sea-Bird instrument is mounted on the SEABOSS system. All data (downcast, drift, upcast) are included. At the end of the cruise, the CTD data are downloaded via a laptop using the Sea-Bird software. The latitude and longitude of the start and end of the video drift are available from 2017-030-FA_station_data_summary dataset, available from the Larger Work citation. The station summary data are available in XLSX, CSV, and shapefile formats.
    Date: 08-Sep-2020 (process 3 of 3)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Blackwood, D.S., and Parolski, K.F., 2001, Seabed observation and sampling system: Sea Technology v. 42, no. 2, p.39-43.

    Valentine, P., Blackwood, D., and Parolski, K., 2000, Seabed observation and sampling system: U.S. Geological Survey Fact Sheet FS-142-00, U.S. Geological Survey, Reston, VA.

    Online Links:


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

  1. How well have the observations been checked?
    These files represent unedited data acquired from the Sea-Bird CTD that was mounted on the SEABOSS system. The data were collected during the descent (downcast) of the SEABOSS to the seabed, its drift over the seabed, and its ascent (upcast) to the water surface. The data values presented here have not been edited or modified. The data accuracy is expected to meet the instrument accuracy specifications.
  2. How accurate are the geographic locations?
    Although these files do not contain latitudes and longitudes, that information can be acquired from the related station data summary file (available from the Larger Work citation). The CTD downcast is located at the start of the video drift, and the upcast is located at the end of the video drift. The location information for stations was acquired from a satellite navigation receiver (Furuno satellite compass SC-30, GPS receiver) at two second intervals with a horizontal accuracy of 10 m. The navigation antenna is located 5.3 m forward of the SEABOSS deployment location. This offset was not accounted for in the navigation acquisition (navigation fixes represent antenna location).
  3. How accurate are the heights or depths?
    The depth values are based on the instrument's pressure gauge and are relative to the local sea surface. The CTD is mounted horizontally on the SEABOSS frame and its maximum depth is approximately 1 meter above the seabed.
  4. Where are the gaps in the data? What is missing?
    The Sea-Bird instrument is mounted on the SEABOSS system. All data (downcast, drift, and upcast) are included. All SEABOSS stations on the cruise have a CTD record. There are a total of 50 CTD data files.
  5. How consistent are the relationships among the observations, including topology?
    The filenames correspond to the station names. Therefore the locations of the casts can be acquired from the station locations in the station data summary file (available from the Larger Work). The naming convention for the CTD casts is staXXXX_ctd_data.txt where XXXX corresponds to the station number.

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: Not to be used for navigation.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: Page C. Valentine
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov
  2. What's the catalog number I need to order this data set? 2017-030-FA_CTD.zip contains the 50 CTD data files and the FGDC CSDGM metadata in TXT, XML, and HTML formats.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    The zip file contains CTD data in TEXT format. The user must have software capable of uncompressing the zip file and using the data files.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
U.S. Geological Survey
Attn: VeeAnn A. Cross
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA

508-548-8700 x2251 (voice)
508-457-2310 (FAX)
vatnipp@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

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