1-meter swath bathymetric grid collected by the U.S. Geological Survey in Moultonborough Bay, Lake Winnipesaukee, New Hampshire in 2005 (UTM Zone 19N, WGS 84, Esri Binary Grid, WINNI_BATHY)

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Frequently anticipated questions:


What does this data set describe?

Title:
1-meter swath bathymetric grid collected by the U.S. Geological Survey in Moultonborough Bay, Lake Winnipesaukee, New Hampshire in 2005 (UTM Zone 19N, WGS 84, Esri Binary Grid, WINNI_BATHY)
Abstract:
In freshwater bodies of New Hampshire, the most problematic aquatic invasive plant species is Myriophyllum heterophyllum or variable leaf water-milfoil. Once established, variable leaf water-milfoil forms dense beds that can alter the limnologic characteristics of a waterbody, impacting natural lacustrine communities and their habitats. Variable leaf water-milfoil infestations also disrupt recreational uses of waterbodies and have negatively affected swimming, boating, fishing, and property values in and around several lakes and ponds in New Hampshire.
In 1965, Moultonborough Bay, Lake Winnipesaukee became the first waterbody in New Hampshire where variable leaf water-milfoil was observed. Variable leaf water-milfoil is native to the Southeastern and Midwestern areas of the United States where more alkaline waters appear to limit the growth of this plant. Outside its native range, however, it adapts well to the relatively acidic, low-alkalinity, and nutrient-poor conditions of oligotrophic lakes and bays similar to Moultonborough Bay.
In 2005, the New Hampshire Department of Environmental Services (NHDES) collaborated with the U.S. Geological Survey to investigate the distribution (presence and density) of variable leaf water-milfoil in Moultonborough Bay. This study utilized geophysical systems and conventional water-quality measurements to identify lake-floor environments that may provide suitable habitat for the establishment and growth of variable leaf water-milfoil. The results of the study are intended to assist resource managers in federal and state agencies by providing methods for detecting variable leaf water-milfoil and for identifying areas susceptible to infestation. Ultimately, this information may lead to early detection, prevention, and more effective mitigation strategies .
Field activity information for this cruise is available on-line through the U.S. Geological Survey Coastal and Marine Geoscience Data System https://cmgds.marine.usgs.gov/fan_info.php?fa=2005-004-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 2014, 1-meter swath bathymetric grid collected by the U.S. Geological Survey in Moultonborough Bay, Lake Winnipesaukee, New Hampshire in 2005 (UTM Zone 19N, WGS 84, Esri Binary Grid, WINNI_BATHY): data release DOI:10.5066/F71N7Z4H, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Denny, J.F., Danforth, W.W., Worley, C.R., and Irwin, B.J., 2014, High-resolution geophysical and sample data collected in Moultonborough Bay, Lake Winnipesaukee, New Hampshire in 2005, USGS Field Activity 2005-004-FA: data release DOI:10.5066/F71N7Z4H, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -71.392577
    East_Bounding_Coordinate: -71.358662
    North_Bounding_Coordinate: 43.729994
    South_Bounding_Coordinate: 43.709154
  3. What does it look like?
    https://cmgds.marine.usgs.gov/data/field-activity-data/2005-004-FA/data/bathymetry/winni_bathy.jpg (JPEG)
    Depth-colored image of bathymetry
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 26-Jul-2005Currentness_Reference: ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 2240 x 2670 x 1, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 19
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 1.000000
      Ordinates (y-coordinates) are specified to the nearest 1.000000
      Planar coordinates are specified in meters
      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: Mean Lake Level
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Value
    Depth in meters relative to Mean Lake Level (Source: Esri)
    Entity_and_Attribute_Overview:
    Swath bathymetry in Esri ArcRaster format. Data values represent depth in meters referenced to Mean Lake Level.
    Entity_and_Attribute_Detail_Citation: Esri

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x 2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

Why was the data set created?

This grid represents approximately 37 kilometers of bathymetric data collected in 2005. These data were collected using an interferometric sonar (Systems Engineering and Assessment Ltd. (SEA) 2000 series) by the U.S. Geological Survey during USGS survey 2005-04-FA. These bathymetric data were used to define the morphology of the bay floor in Moultonborough Bay, Lake Winnipesaukee, New Hampshire as part of a collaborative USGS and New Hampshire Department of Environmental Services research program to assess the distribution of variable leaf water-milfoil. The morphology of the bay floor aids in defining the physical characteristics of specific benthic habitat environments within the bay.

How was the data set created?

  1. From what previous works were the data drawn?
    none (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, Raw Bathymetric Data.

    Type_of_Source_Media: online
    Source_Contribution:
    Swath-bathymetric and acoustic-backscatter data were acquired with a SEA, Ltd., Submetrix 2000 Series interferometric sonar operating at a 234-kHz frequency. The SEA Submetrix 2000 Series transducers were mounted at the bow of the USGS R/V Rafael. Approximately 37 km of swath bathymetric data were collected.
    SEA RTS2000 acquisition software (version year 2005) was used to digitally log the bathymetric data at a maximum 50 meter range (100 meter swath width) and 2048 samples per ping in the SEA SXR format. In shallow water areas, the swath width did not achieve the full 50-meter range, but varied from roughly 5x water depth to the maximum 50-meter range (i.e. swath width varied from approximately 15 meter to 100 meters depending on water depth). Data collection parameters are saved as a RTS2000 session file in SEA SXS format.
    An Octopus F180R Attitude and Positioning system (see: http://www.codaoctopus.com/motion/f180/index.asp) recorded ship motion (heave, pitch, roll, and yaw). These data were transmitted via network connection to the RTS2000 data acquisition software. The Octopus F180R Inertial Measurement Unit (IMU) was mounted directly above the SEA Submetrix 2000 Series transducers, to minimize lever arm offsets that can lead to positioning errors. The F180R uses two L1 antennas for position and heading accuracy. The antennas are mounted on a rigid horizontal pole, 3 meters above the F180R IMU, with a horizontal separation of 1 meter and are offset from the IMU in a forward/aft configuration. The forward offset of the primary antenna from the IMU is 0.5 meters, with no port/starboard offset.
    Eight sound-velocity profiles were acquired during survey operations at roughly 1 to 3 hour intervals using an Applied Microsystems SV Plus Velocimeter (Applied Microsystems, 2008). Sound-velocity profiles 1 - 3 were collected during JD 206 for lines 1 - 42. Sound-velocity profiles 4 - 8 were collected during JD207 for lines 43 - 112. Only lines 43 - 112 were used to generate the final bathymetric grid.
    Vertical accuracy of the raw data based on system specifications may approximate 1% of water depth, 0.01 to 0.15 meters within the survey area. However, overall vertical accuracies on the order of + or - 1 meter are assumed based on the following considerations: WAAS navigation vertical accuracies; the Coda Octopus F180 Attitude and Positioning system, used to correct for vessel roll, pitch, heave, and yaw, has a theoretical vertical accuracy of a few mm; refraction artifacts were minimized by acquiring a range of sound velocity profiles with a hand-casted Applied MicroSystems SV Plus sound velocimeter during the survey. Changes in ship draft due to water and fuel usage were not considered. Vertical resolution is on the order of 0.1 meters.
  2. How were the data generated, processed, and modified?
    Date: 2005 (process 1 of 4)
    Converting Raw (SXR) to Field-Processed (SXP) Files:
    Raw SXR bathymetry data were acquired with the SEA RTS2000 (version year 2005) software and used to generate field-processed SEA RTS2000 SXP files. The following information was stored within the RTS2000 session files and applied to the raw bathymetric soundings: eight sound velocity profiles to minimize refraction artifacts due to fluctuations from the speed of sound in the water column, roll offsets calculated during pre-survey patch test, draft of the transducer below the water line, and the measured angles and relative positions of the swath bathymetric transducers. The RTS2000 software applies the pitch, roll, heave, yaw and heading data supplied by the F180R IMU, to compensate depth solutions across the swath for any ship motion. Some bathymetric filtering was applied during acquisition, however final processing, filtering and editing were completed with The University of New Brunswick, Ocean Mapping Group (OMG) SwathEd software suite (see process step 2).
    Jane F. Denny performed this and all subsequent process steps. Person who carried out this activity:
    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
    Date: 2005 (process 2 of 4)
    Generating Bathymetric Grid: University of New Brunswick, Ocean Mapping Group (OMG) SwathEd Multibeam Processing Software (Beaudoin, 2002)
    1) Bathymetric data (raw SXR files), sound velocity profiles, and system configuration information (antenna offsets, transducer offsets, water level, attitude and positioning) were used to generate a composite bathymetric grid using the University of New Brunswick's Ocean Mapping Group (OMG) SwathEd multibeam processing software. The raw Submetrix 2000 Series data were "unraveled" and reformatted into the OMG format. This process creates several files on disk: a) bathymetric soundings (*.merged) b) raw backscatter (*.ss) c) navigation (*.ascii_nav and *.nav) d) parameter files describing the configuration of the system (i.e. offsets between motion reference unit and GPS antenna, etc.). This process also incorporates the sound velocity profiles in order to properly account for any refraction due to fluctuations in the speed of sound within the water column. (All data were processed, however only lines 43 - 112 were used to generate the bathymetric grid).
    2) The OMG formatted bathymetric data (*.merged) were then graphically edited on a line-by-line basis using the SwathEd multibeam processing software. This enabled editing individual lines on a "ping-by-ping" basis, both in the across- and along-track dimension. Spurious or erroneous data were removed. The navigation data (*.nav) were also graphically examined for each line of data.
    3) SwathEd Software was used to grid the bathymetric data at 1 m grid cell size utilizing the following 'weigh_grid' command.
    weigh_grid -omg -butter -power 2 -cutoff 2 -lambda 0.5 bathy_grid *.merged
    4) The gridded data were then viewed using the SwathEd Jview command in order to assess roll misalignment and any remaining navigational errors. The PatchTool (a Quality Control tool) was used to assess the roll misalignment of the data that can arise due to the minor offsets in the nominal transducer angles entered in the configuration file and used during data processing. After editing was completed, the corrected roll values and navigation were remerged with the OMG-formatted bathymetric data (*.merged) using the mergeNav and mergeAtt commands.
    mergeNav -use_params 0 -nav *.nav -swath *.merged)
    5) The remerged data were regridded to assess if further edits were needed.
    weigh_grid -omg -butter -power 2 -cutoff 2 -lambda 0.5 bathy_grid *.merged
    The roll misalignment artifacts were no longer visible in the gridded data and spurious navigation positions were removed.
    6) The 1 meter grid was then exported to an xyz ASCII file format. (r4toASCII -utm -merid -69 bathy_1m.xyz)
    Date: 2005 (process 3 of 4)
    Import to ArcGIS (version 9.0):
    The exported data (bathy_1m.xyz, floating point) were then imported to ArcGIS 9.0 using the ASCIItoRaster command (Conversion Tools - To Raster - ASCIItoRaster). The projection was then defined: UTM, zone 19 projection, WGS84 Ellipsoid.
    Date: 06-Apr-2017 (process 4 of 4)
    The online links to the data were updated to reflect the new server hosting the data. Additionally, other small edits could be made to the metadata, such as modifying http to https where appropriate. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. 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?
    Argue, Denise M., Kiah, Richard G., Denny, Jane F., Deacon, Jeffrey R., Danforth, William W., Johnston, Craig M., and Smagula, Amy P., 2007, Relation of Lake-Floor Characteristics to the Distribution of Variable Leaf Water-Milfoil in Moultonborough Bay, Lake Winnipesaukee, New Hampshire, 2005: Scientific Investigations Report 2007-5125, U.S. Geological Survey, Reston, Virginia.

    Online Links:

    Beaudoin, Jonathan, 2002, Hitchhiker's Guide to Swathed...: Online Manual http://www.omg.unb.ca/~jonnyb/processing/definitive_swathed/index.html, University of New Brunswick Ocean Mapping Group, Fredericton, New Brunswick, Canada.

    Online Links:


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

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    Navigation was acquired with Wide Area Augmentation System ( WAAS), which is accurate to + or - 1 to 2 meters, horizontally. The forward, or primary, Coda Octopus F180R Attitude and Positioning system antenna was used to acquire data and transmit via a network connection to the SEA RTS2000 data collection software. The F180R Attitude and Positioning system uses 2 L1 antennas for position and heading and an Inertial Measurement Unit (IMU) for motion sensing. The F180R IMU is mounted on the rigid bow mount used to deploy the SEA Submetrix 2000 Series bathymetric system, and is located directly above the SEA Submetrix 2000 Series transducers. The F180R antennas are mounted on a rigid horizontal pole, 3 meters above the F180R IMU, offset in a forward/aft configuration. These offsets were corrected within the RTS2000 acquisition software.
  3. How accurate are the heights or depths?
    The Wide Area Augmentation System (WAAS) navigation was used to record vertical positioning of bathymetric soundings during data acquisition. WAAS is a GPS-based navigation system providing precision guidance to aircraft and provides vertical accuracies of + or - 1.5 meters. Higher precision vertical positioning (for example, RTK-navigation) was not available during this survey effort.
    Vertical accuracy of the raw data based on system specifications may approximate 1% of water depth, 0.01 to 0.15 meters within the survey area. However, overall vertical accuracies on the order of + or - 1 meter are assumed based on the following considerations: WAAS navigation vertical accuracies; the Coda Octopus F180 Attitude and Positioning system, used to correct for vessel roll, pitch, heave, and yaw, has a theoretical vertical accuracy of a few mm; refraction artifacts were minimized by acquiring a range of sound velocity profiles with a hand-casted Applied MicroSystems SV Plus sound velocimeter during the survey. Changes in ship draft due to water and fuel usage were not considered.
    Absolute water level values are reported as meters and referenced to Mean Lake Level, which is defined to be 504.32 meters above Mean Sea Level (NGVD29). Mean Lake Level measured during the USGS geophysical survey (July 24 - July 30, 2005) averaged 4 feet above Mean Lake Level as reported by the New Hampshire Department of Environmental Services (http://des.nh.gov/index.htm). This value (4 feet (1.3 meters)) is within the vertical accuracy of the survey. Therefore no additional offsets were applied to the data in order to reference to Mean Lake Level.
  4. Where are the gaps in the data? What is missing?
    Lines 43 - 112 of swath bathymetric data were used to generate the bathymetric grid. Data gaps present within the grid fall within areas of the bay that were too shallow to access with the R/V Rafael. Data gaps along the coastline are due to insufficient bottom coverage with the SEA Submetrix 2000 Series system. Data from tieline L110f1 was not used in the bathymetric grid because of the poor quality of the bathymetric data.
    Lines 1 - 42 were collected during JD206 and completely covered the survey area, however the sidescan-sonar system (Edgetech 4200) failed during survey operations. The backup sidescan-sonar system (Klein 3000 sidescan-sonar) was configured during JD207. As such, the survey area was resurveyed on JD 207 and those data were used for generating bathymetric surfaces and interpretations.
  5. How consistent are the relationships among the observations, including topology?
    This grid represents interpolated data; processed to account for gaps that occurred along-track and between adjacent lines.

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:
These data are NOT to be used for navigation. Mariners should refer to the appropriate nautical chart. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
  2. What's the catalog number I need to order this data set? The file winni_bathy.zip contains the Esri binary grid (in the folders winni_bathy and info). In addition to the grid, the zip file also contains the browse graphic (winni_bathy.jpg) and the FGDC CSDGM metadata in the following formats: XML, HTML, FAQ and text.
  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?
    These data are available as a ArcInfo 32-bit floating point binary grid in Esri format. The floating point binary grid and associated 'info' folder are stored in one folder 'grid' that has been compressed using WinZip (ver. 17.5) software. To utilize these data, the user must have software capable of uncompressing the zip file and importing and viewing an Esri ArcRaster grid. The zip file also contains associated metadata.

Who wrote the metadata?

Dates:
Last modified: 06-Apr-2017
Last Reviewed: 2013
Metadata author:
Jane F. Denny
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, Massachusetts
USA

508-548-8700 x2311 (voice)
508-457-2310 (FAX)
jdenny@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.9.36 on Thu Apr 06 14:09:03 2017