CTD (conductivity-temperature-depth) data collected by the U.S. Geological Survey on Stellwagen Bank during three surveys aboard the R/V Auk, September 2020 to August 2021

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Frequently anticipated questions:

What does this data set describe?

Title:
CTD (conductivity-temperature-depth) data collected by the U.S. Geological Survey on Stellwagen Bank during three surveys aboard the R/V Auk, September 2020 to August 2021
Abstract:
These data are a 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. The work 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 a total of 169 locations on Stellwagen Bank during three separate surveys from September 2020 to August 2021. During these surveys 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 including temperature, salinity, density, and fluorescence.
Supplemental_Information:
Additional information regarding the field activities associated with these data can be obtained from the following locations https://cmgds.marine.usgs.gov/fan_info.php?fan=2020-012-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-016-FA, and https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-017-FA .
  1. How might this data set be cited?
    Valentine, Page C., 20230321, CTD (conductivity-temperature-depth) data collected by the U.S. Geological Survey on Stellwagen Bank during three surveys aboard the R/V Auk, September 2020 to August 2021: data release DOI:10.5066/P9G7QARQ, 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., 2023, Sea-floor Sediment Samples, Seabed and Sample Imagery, and CTD Instrument Data Collected on Stellwagen Bank from September 2020 to August 2021: data release DOI:10.5066/P9ERNGJ2, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2023, Sea-floor sediment samples, seabed and sample imagery, and CTD instrument data collected on Stellwagen Bank from September 2020 to August 2021: U.S. Geological Survey data release, https://doi.org/10.5066/P9G7QARQ .
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.562830
    East_Bounding_Coordinate: -70.118010
    North_Bounding_Coordinate: 42.440290
    South_Bounding_Coordinate: 42.096030
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 24-Sep-2020
    Ending_Date: 04-Aug-2021
    Currentness_Reference:
    Ground condition of when data were collected. These data were collected during three separate surveys, with the following ranges of dates for each survey: field activity 2020-012-FA: 20200924 to 20200925; field activity 2021-016-FA: 20210721 to 20210723; and field activity 2021-017-FA: 20210802 to 20210804.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: text file for water column profile
  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?
      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 are included in an ASCII text file with an eleven-row header that gives the station number and the output format of the data with descriptions of what information is in each column. The remaining rows (starting at row 12) are columns of measured values that are space-delimited and correspond to the columns listed in the header.The following stations in field activity 2021-017-FA only have a 10 row header, each omitting a blank row: sta5062, sta5095, and sta5104. (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 - 1990 International Temperature Scale), 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 4955

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

-0.243    20.2753     0.0102    -1.8440    -0.0068    -0.0088  0.000e+00
-0.247    20.2576     0.0103    -1.8403    -0.0090    -0.0076  0.000e+00
-0.245    20.2324     0.0102    -1.8351    -0.0068    -0.0088  0.000e+00
-0.247    20.2184     0.0103    -1.8321    -0.0060    -0.0076  0.000e+00
-0.247    20.1960     0.0000    -1.8353    -0.0060    -0.0084  0.000e+00
-0.245    20.1728     0.0103    -1.8226    -0.0045    -0.0088  0.000e+00
-0.245    20.1578     0.0103    -1.8194    -0.0052    -0.0076  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 in the header rows 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)
    whsc_data_contact@usgs.gov
    Contact_Instructions:
    The contact email address is a generic address in the event the person is no longer with the USGS.

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: 2021 (process 1 of 2)
    These data were collected with a Sea-Bird CTD (conductivity, temperature, depth) instrument - an SBE19plusV2 SeaCAT Profiler CTD. This instrument was deployed on SEABOSS. 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. See the cross-references for additional information on the SEABOSS (Blackwood and Parolski, 2001; Valentine and others, 2000). The CTD was mounted horizontally on the SEABOSS frame and its maximum depth was approximately 1 meter above the seabed. The specifications for the CTD instrument were 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 (CHL is Chlorophyll and TURB is turbidity): 
    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 Siemens per meter (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 parts per million (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
    Data were collected from 2020 to 2021 with the process date representing the most recent acquisition year. 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: 2021 (process 2 of 2)
    At the end of each cruise, the CTD data are downloaded via a laptop using the Sea-Bird software. All data (downcast, drift, and upcast) are included in this dataset. The latitude and longitude of the start and end of the video drift are available from 2020-2021_station_data_summary dataset, available from the Larger Work citation. The station summary data are available in XLSX, CSV, and shapefile formats.
    Data were collected from 2020 to 2021 with the process date representing the most recent acquisition year. 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
  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:

    Valentine, P.C., and Cross, V.A., 2019, Location and analyses of sediment samples collected on Stellwagen Bank off Boston, Massachusetts from November 5, 2013 to April 30, 2019 on U.S. Geological Survey field activities: data release DOI:10.5066/P9FWFLPD, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication includes the grain-size analyses of the sediment samples collected on 20 other field activities.

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 SEABed Observation and Sampling System (SEABOSS) frame. 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 (2020-2021_station_data_summary 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) in geographic coordinates (World Geodetic System of 1984 [WGS 84]) with a horizontal accuracy of 10 m. Cruise 2020-012-FA acquired navigation at two-second intervals on September 24 and five-second intervals on September 25. Cruise 2021-016-FA acquired navigation at a two-second interval. Cruise 2021-017-FA acquired navigation at a two-second interval. The navigation antenna was located 5.3 m forward of the SEABOSS deployment location. This offset was not accounted for in the navigation acquisition so navigation fixes represent the antenna location. The SEABOSS may also drift away from the survey vessel when deployed to the sea floor.
  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 was mounted horizontally on the SEABOSS frame and its maximum depth was approximately 1 meter above the seabed. The pressure gauge accuracy is 0.1% of water depth as stated by the manufacturer.
  4. Where are the gaps in the data? What is missing?
    All the Sea-Bird instrument data (downcast, drift, and upcast) that were collected during the surveys are included; however, not all stations have a CTD record. Stations 5021 and 5029 from 2021-016-FA do not have a CTD record because the CTD was not turned on prior to the deployment of the SEABOSS system. Station 5023 from that same field activity is extremely short, so probably does not represent the full deployment. There are CTD data for 167 of the 169 SEABOSS sampling stations.
  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 citation). The naming convention for the CTD casts is staXXXX_ctd_data.txt where XXXX corresponds to the station number. All the field activities took place on the Stellwagen Bank National Marine Sanctuary's research vessel, R/V Auk. Although these data represent three separate field activities, the set-up and acquisition on all the cruises is consistent with the exception of the navigation - which was sometimes acquired at 2-second intervals and sometimes at 5-second intervals. The files are all structured the same with the exception of the following stations from field activity 2021-017-FA: sta5062, sta5095, and sta5104. Stations 5062 and 5095 omit a blank row after the station name line, and station 5104 omits a blank row after the output data format line.

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 - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    USA

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? This dataset is comprised of three different field activities. The data from each field activity is contained in a zip file: 2020-012-FA_CTD.zip (33 files), 2021-016-FA_CTD.zip (41 files), and 2021-017-FA_CTD.zip (93 files). The total number of CTD data files is 167. The FGDC CSDGM metadata in XML format is also included.
  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 for other purposes, nor on all computer systems, 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?
    The dataset 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: 21-Mar-2023
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)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with the USGS.
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9G7QARQ/CTD_2020-2021_meta.faq.html>
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