Preliminary bathymetric map of Mother Goose Lake, Alaska Peninsula

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Frequently-anticipated questions:


What does this data set describe?

Title:
Preliminary bathymetric map of Mother Goose Lake, Alaska Peninsula
Abstract:
In preparation for bottom sediment coring at Mother Goose Lake, bathymetric data was collected using a Lowrance Sonar "fishfinder" (model LcX-17M) in August 2006 and August 2007. A 5-meter bathymetric contour map of the lake bottom was constructed using the GPS-sonar data in conjunction with field observations. The contour data and GPS location and depth data are provided in ESRI shapefile format for use in Geographic Information System (GIS) software.
Supplemental_Information:
The layers listed below are present as ArcGIS shape files. Attribute information for the following layers (entities) is included in this metadata file under the "Entity_and_Attribute_Information" section. Each layer is listed and described in detail under its own heading starting "Entity_Type_Label." Layers include:
MGL_islands_polyline     Outline of the islands in Mother Goose Lake.
MGL_shore_polyline     Outline of the Mother Goose Lake shoreline.
MGL_contour_5m_polyline     5-meter bathymetric contour map of Mother Goose Lake.
MGL_gps_depth_point     Lat-Long-Depth point file of data collected at Mother Goose Lake used to derive the bathymetric map.
  1. How should this data set be cited?

    Schaefer, J.R., Wallace, K.L., and Kassel, C.M., 2008, Preliminary bathymetric map of Mother Goose Lake, Alaska Peninsula: Raw Data File RDF 2008-3, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, Alaska - USA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -157.403722
    East_Bounding_Coordinate: -157.233482
    North_Bounding_Coordinate: 57.231361
    South_Bounding_Coordinate: 57.178854

  3. What does it look like?

    MGL_bathymetry.jpg (JPEG)
    Bathymetric contour map of Mother Goose Lake

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 24-Aug-2006
    Ending_Date: 25-Aug-2006
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set.

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 4
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -159
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.01
      Ordinates (y-coordinates) are specified to the nearest 0.01
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.25722210088.

  7. How does the data set describe geographic features?

    MGL_islands_polyline.shp
    1 object. Polyline defining the outline of the islands in Mother Goose Lake. This feature was not assigned any user defined attribute. (Source: This report)

    MGL_contour_5m_polyline.shp
    Polyline file representing 10-meter bathymetric contours of Mother Goose Lake. (Source: This report)

    contour_m
    line joining points of equal depth in 5-meter intervals (Source: This report)

    Range of values
    Minimum:5
    Maximum:50
    Units:meters

    MGL_gps_depth_point.shp
    25823 points of decimal degree latitude and longitude listed in both NAD83 datum and NAD27 datum. Depth listed in both feet and meters. (Source: This report)

    Depth_ft
    depth, in feet, below lake surface (Source: This report)

    Range of values
    Minimum:0.4
    Maximum:263.639
    Units:feet

    Depth_m
    Depth, in meters, below lake surface (Source: This report)

    Range of values
    Minimum:0.12192
    Maximum:80.3571
    Units:meters

    LongNAD83
    Longitude of depth measurement in decimal degrees, NAD83 datum (Source: This report)

    Range of values
    Minimum:-157.363
    Maximum:-157.258
    Units:degrees

    LatNAD83
    Latitude of depth measurement reported in decimal degrees, NAD83 datum (Source: This report)

    Range of values
    Minimum:57.1805
    Maximum:57.2252
    Units:degrees

    LongNAD27
    Longitude of depth measurement in decimal degrees, NAD27 datum. (Source: This report)

    Range of values
    Minimum:-157.361
    Maximum:-157.256
    Units:degrees

    LatNAD27
    Latitude of depth measurement in decimal degrees using NAD27 datum. (Source: This report)

    Range of values
    Minimum:57.1812
    Maximum:57.226
    Units:degrees

    MGL_shore_polyline
    1 object. Polyline defining the shore of Mother Goose Lake. This feature was not assigned any user defined attribute. (Source: This report)

    Entity_and_Attribute_Overview:
    Below is a brief description of the four ESRI shapefiles found in this dataset: MGL_islands_polyline - Outline of the islands in Mother Goose Lake. MGL_shore_polyline - Outline of the Mother Goose Lake shoreline. MGL_contour_5m_polyline - 5-meter bathymetric contour map of Mother Goose Lake. MGL_gps_depth_point - Point file of GPS-sonar track data used to construct the bathymetric map. Positional data is reported in decimal degrees of latitude and longitude (NAD 27 datum). Depth data is provided in both feet and meters.
    Entity_and_Attribute_Detail_Citation: This report


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?

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    GIS Data Manager/Cartographer
    3354 College Road
    Fairbanks, AK 99709-3707

    (907) 451-5029 (voice)
    (907) 451-5050 (FAX)
    dggspubs@alaska.gov

    Contact_Instructions:
    You may view our web site at <http://www.dggs.dnr.state.ak.us> for the latest information on available data. Please e-mail your questions and data requests when possible since our web site and e-mail address will remain current even if our phone number and mailing address change.


Why was the data set created?

The purpose of this bathymetric data release is to provide scientific collaborators who are working on the Chiginagak volcano acid flood event, such as geologists and fisheries biologists, with depth information of Mother Goose Lake.


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: Aug-2006 (process 1 of 1)
    Lowrance (model LcX-17M) GPS-Sonar data was collected at Mother Goose Lake on August 24-25, 2006 and August 15-19, 2007 . Lowrance GPS data is collected and stored in a Mercator projection with a datum of WGS84. Sonar log file data was converted to a comma-delimited text file using a free utility from Lowrance called Sonar Viewer (<http://www.lowrance.com/Software/PCSoftware/sonar_viewer.asp>). This text file was imported into Microsoft Excel, and the following conversion was applied to convert the Mercator WGS84 projection to Geographic decimal degree coordinates in a NAD83 datum: Excel formula to convert Mercator WGS84 location (X,Y) to Geographic Coordinates NAD83 to (longitude, latitude) decimal degrees
    Latitude =RadToDeg*((2*ATAN(EXP(Y/SemiMinor))-PI()/2))
    Longitude =(X*RadtoDeg)/SemiMinor
    Where RadtoDeg = 57.2957795132 SemiMinor = 6356752.3142 X = Lowrance position X in Mercator WGS84 Y = Lowrance position Y in Mercator WGS84
    Depth information stored in feet was converted to meters by applying a conversion factor of 0.3048. This data was then imported into MapInfo Professional 8.0 to display the depth data geospatially. The projection was converted to UTM zone 4, NAD83. Decimal degree latitude and longitude information in both NAD83 and NAD27 datums were generated by projecting and updating columns in MapInfo. Using both field observations of lake depth, and the geospatially accurate sonar data, a contour of lake depth was created by digitizing around depth points in MapInfo. The file was then exported to ESRI shapefile format using MapInfo Professional 8.0 Universal Translator.
    Shoreline and Islands (MGL_shore_polyline and MGL_islands_polyline): The polylines defining both the Mother Goose Lake shoreline and island shorelines were created in MapInfo Professional 8.0 using a May 8, 2005, 30-meter-pixel-width, Landsat 7 image as the base. The Landsat image was provided in a UTM zone 4 projection with a datum of WGS84. After construction, the polyline files were reprojected in MapInfo to UTM zone 4, NAD27, before exporting to shapefile format. The Landsat 7 image was set at a zoom scale of 1:10,000 during construction of the shoreline and island polyline files.

  3. What similar or related data should the user be aware of?


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

  1. How well have the observations been checked?

    Attributes in this dataset consist of positional information reported in latitude and longitude (decimal degrees in both NAD27 and NAD83 datums), and depth information reported in feet and meters. Original latitude, longitude, and depth attributes were recorded digitally by the Lowrance GPS-sonar unit. Original location information was recorded in a Mercator projection with the WGS84 datum. Depth in feet was converted to depth in meters by applying a conversion factor of 0.3048. The resulting data is in file MGL_gps_depth_point. Attributes in the bathymetric contour data file MGL_contour_5m_polyline consist of labels of depth in meters and were added manually as the polylines were constructed in a GIS from the MGL_gps_depth_point file.

  2. How accurate are the geographic locations?

    GPS-sonar data was collected with a Lowrance "fishfinder" (model LcX-17M) with a positional accuracy of approximately 15 meters. However, after mapping the sonar data in a GIS in conjunction with a vector shoreline constructed from Landsat imagery, the position of data points appears to be up to 150m off (for example, the track data in the file MGL_gps_depth_point shows points going up onto shore.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    This dataset includes preliminary bathymetric data collected over a 2-day period in August of 2006 and a 5-day period in August 2007. The footprint of the GPS-sonar track data used to derive the contour map is small, thus the contour map represents a generalized illustration of the true bathymetry of Mother Goose Lake.

  5. How consistent are the relationships among the observations, including topology?

    not applicable


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
This report, map, and/or dataset are available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. User specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys.

  1. Who distributes the data set? (Distributor 1 of 1)

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    3354 College Road
    Fairbanks, AK 99709

    907-451-5020 (voice)
    907-451-5050 (FAX)
    dggspubs@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our Web site (<http://www.dggs.dnr.state.ak.us>) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set?

    RDF 2008-3

  3. What legal disclaimers am I supposed to read?

    The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requester or anyone else exceed the fee paid for the electronic service or product.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    Please check the MapInfo web site (<http://www.mapinfo.com/>) for the latest documentation on importing ESRI shape files.


Who wrote the metadata?

Dates:
Last modified: 06-May-2008
Last Reviewed: 06-May-2008
To be reviewed: 19-Mar-2009
Metadata author:
Janet Schaefer
3354 College Rd
Fairbanks, AK 99709

907-451-5005 (voice)
janet.schaefer@alaska.gov

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.6 on Tue May 06 14:29:37 2008