Color-hillshade relief GeoTIFF image of the Potomac River/Chesapeake Bay Area (CLRHSHD_POTO.TIF, UTM, Zone 18, NAD83)

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Frequently anticipated questions:

What does this data set describe?

Title:
Color-hillshade relief GeoTIFF image of the Potomac River/Chesapeake Bay Area (CLRHSHD_POTO.TIF, UTM, Zone 18, NAD83)
Abstract:
In order to test hypotheses about groundwater flow under and into Chesapeake Bay, geophysical surveys were conducted by U.S. Geological Survey (USGS) scientists on Chesapeake Bay and the Potomac River Estuary in September 2006. Chesapeake Bay resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge, which are contributing to eutrophication. The USGS has performed many related studies in recent years to provide managers with information necessary to make informed decisions about this issue. The research carried out as part of the study described here was designed to help refine nutrient budgets for Chesapeake Bay by characterizing submarine groundwater flow and discharge of groundwater beneath part of the mainstem and a major tributary, the Potomac River Estuary.
  1. How might this data set be cited?
    Cross, VeeAnn A., 2010, Color-hillshade relief GeoTIFF image of the Potomac River/Chesapeake Bay Area (CLRHSHD_POTO.TIF, UTM, Zone 18, NAD83): Open-File Report 2009-1151, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A., Foster, David S., and Bratton, John F., 2010, Continuous Resistivity Profiling and Seismic-Reflection Data Collected in 2006 from the Potomac River Estuary, Virginia and Maryland: Open-File Report 2009-1151, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -77.387222
    East_Bounding_Coordinate: -75.604370
    North_Bounding_Coordinate: 38.729651
    South_Bounding_Coordinate: 37.706801
  3. What does it look like?
    http://pubs.usgs.gov/of/2009/1151/data/basemap/clr_hshd.gif (GIF)
    Thumbnail image of the color-hillshade relief image from the Potomac River Estuary area.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1998
    Currentness_Reference:
    Publication data of the original datasets used to general the elevation grid from which this was derived.
  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 3702 x 5144 x 1, type Pixel
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      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 30.000000
      Ordinates (y-coordinates) are specified to the nearest 30.000000
      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 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.
  7. How does the data set describe geographic features?

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • VeeAnn A. Cross
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

Why was the data set created?

The purpose of this dataset is to provide the color-hillshade relief image of the Potomac area in GeoTIFF format (UTM zone 18, NAD83) that can be viewed by a variety of software programs.

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: 2009 (process 1 of 13)
    Within ArcMap 9.2 a special legend was created for the poto_area elevation grid. The grid intervals were set using VACExtras version 2.1 - Raster - Legend Classifier. (VACExtras is an extension written and maintained in Woods Hole, MA for a collection of tools useful in ArcGIS). Once the legend intervals were established, colors at critical intervals were chosen and then these colors were ramped over the entire grid within the symbology window of the dataset. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • poto_area
    Data sources produced in this process:
    • poto_area
    Date: 2009 (process 2 of 13)
    VACExtras 2.1 (within ArcMap 9.2) was then used to export this specialized color map to a text file in Fledermaus RGB format (Raster - Export Fledermaus Color Legend). Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • poto_area
    Data sources produced in this process:
    • arcgiscolor.txt
    Date: 2009 (process 3 of 13)
    An AWK script was written to reformat this text file into a format compatible with a GMT RGB ASCII color map. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • arcgiscolor.txt
    Data sources produced in this process:
    • tst.cpt
    Date: 2009 (process 4 of 13)
    The combined elevation grid (poto_area: http://pubs.usgs.gov/of/2009/1151/data/basemap/elevation/poto_area.zip) was loaded into Mirone, version 1.5.0. Mirone is a MATLAB-based framework tool that allows the display and manipulation of a large number of grid format. This particular version is a stand-alone version intended to run under Windows (not requiring MATLAB). Mirone is capable of reading an ArcGIS binary grid. With the grid loaded, the newly generated ASCII color map was also loaded (Image - Color Palettes - Change Palette - File - Read GMT Palette - As Master). Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • poto_area
    • tst.cpt
    Date: 2009 (process 5 of 13)
    Using Mirone - Image - Illuminate - GMT grdgradient - option 1 (which is the GMT grdgradient classic), setting the Azimuth to 315 - the falsely colored grid is converted to a color-hillshade. This display was then exported as a GeoTIFF image using File - Save Image As - GeoTIFF. The option to "Preserve Image original size" was selected. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • poto_area
    • tst.cpt
    Data sources produced in this process:
    • clrhshd_poto.tif
    Date: 2009 (process 6 of 13)
    GeoTIFFExamine was then used to open the GeoTIFF to verify the header information and to write a TIFF world file including this information. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • clrhshd_poto.tif
    Data sources produced in this process:
    • clrhshd_poto.tfw
    Date: 2009 (process 7 of 13)
    This GeoTIFF is compressed with LZW compression, which is not compatible with all software. Therefore, this TIFF image was opened in CorelPhotoPaint version 11 and the image was saved in an uncompressed format. Data sources used in this process:
    • clrhshd_poto.tif
    Data sources produced in this process:
    • clrhshd_poto.tif
    Date: 2009 (process 8 of 13)
    Using CorelPhotoPaint version 11 to save the image without LZW compression erased the georeferencing information in the header of the TIFF image. GeoTIFFExamine was used to retrieve the georeferencing information from the world file and repopulate the TIFF header making this image a GeoTIFF. Data sources used in this process:
    • clrhshd_poto.tfw
    Data sources produced in this process:
    • clrhshd_poto.tif
    Date: 2009 (process 9 of 13)
    For maximum compatibility and ease of use with ArcMap 9.2 and higher, the image was loaded into ArcMap 9.2. The projection of the image was defined using ArcToolbox - Data management Tools - Projections and Transformations - Define Projection. The coordinate system selected was NAD_1983_UTM_Zone_18N. Even though the image is a GeoTIFF and there is a world file, this additional step produces an AUX file with all the projection information that is easily read by ArcMap. Data sources used in this process:
    • clrhshd_poto.tif
    Data sources produced in this process:
    • clrhshd_poto.aux
    Date: 16-Jun-2016 (process 10 of 13)
    Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    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
    Date: 20-Jul-2018 (process 11 of 13)
    USGS Thesaurus keywords added to the keyword section. 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
    Date: 18-Nov-2019 (process 12 of 13)
    Crossref DOI link was added as the first link in the metadata. 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
    Date: 08-Sep-2020 (process 13 of 13)
    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?
    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Special Projects (SP), 1998, Chesapeake Bay, VA/MD (M130) Bathymetric Digital Elevation Model (30 meter resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA: NOAA's Ocean Service, Special Projects (SP), Silver Spring, MD.

    Online Links:

    U.S. Geological Survey (USGS), EROS Data Center, 1999, National Elevation Dataset: U.S. Geological Survey, Sioux Falls, SD.

    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?
    This GeoTIFF is a combination of two dataset that provide the best-available data for the land elevations and the bathymetry of Chesapeake Bay. The 7.5-minute elevation data for the conterminous United States are the primary initial source data for the land elevation and were acquired from the National Elevation Dataset (NED). The bathymetry dataset was acquired from the NOAA estuarine bathymetry website. This dataset was derived from two hundred ninety-seven surveys dating from 1850 to 1993. The NED website does not specify any value for horizontal accuracy. According to the metadata accompanying the bathymetry dataset, the horizontal accuracy is expressed as an estimated root mean square error (RMSE). The estimate of the RMSE is based upon horizontal accuracy tests of the source soundings used to generate the DEM. As a first approximation the locational accuracy of the source soundings are 0.0015 m at source "Smooth Sheet" scale (120 m at 1:80,000 to 15 m at 1:10,000). Smooth Sheets are maps generated as a principle product of each (historic) hydrographic survey with fully corrected soundings plotted on them. In both cases the user needs to refer to the original datasets to establish the details of the data and their estimates of accuracy.
  3. How accurate are the heights or depths?
    The metadata accompanying the NED dataset does not specify a vertical accuracy. However, the website indicates the vertical accuracy of the National Elevation Dataset (NED) varies spatially because of the variable quality of the source digital elevation models (DEMs). As such, the NED inherits the accuracy of the source DEMs. The most recently published figure of overall absolute vertical accuracy expressed as the root mean square error (RMSE) is 2.44 meters. The estuarine bathymetry metadata indicates the vertical RMSE statistic is used to describe the vertical accuracy of a DEM. It encompasses both random and systematic errors introduced during production of the data. The RMSE is encoded in element number 5 of record C of the DEM. This accuracy estimate includes components related to quantization of the source soundings (1.3 to 0.15 m), the systematic editing of the source data (1percent or 0.10m), un-sampled bathymetric features (estimated at less than 5 percent of depth), time related changes (erosion, deposition, and seismic shifts), and dredging operations (cut and fill). It is estimated that the accuracy of the Bathymetric DEMs is 2 percent of depth or 1 meter for depths grater than 20 meters and 2 percent of depth or 0.20 meters for depths shallower than 20 meters. THESE DEMs SHOULD NOT BE USED FOR NAVIGATION. The two datasets used to create this merged product are referenced to different vertical datums. The NED data use a vertical datum of NAVD88 while the estuarine data simply specifies the vertical datum as referenced to the local tidal datum at the time of the hydrographic survey. No adjustment was made to the individual datasets to attempt to eliminate this discrepancy. The user needs to refer to the original datasets to establish the details of the data and their estimates of accuracy.
  4. Where are the gaps in the data? What is missing?
    This dataset represents the complete elevation information for the area of interest in GeoTIFF format.
  5. How consistent are the relationships among the observations, including topology?
    Information unavailable from original metadata.

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:
The public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey and the National Oceanic and Atmospheric Administration (NOAA) National Ocean Service (NOS) as the originators of the individual datasets. These data are not to be used for navigation.
  1. Who distributes the data set? (Distributor 1 of 1)
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
  2. What's the catalog number I need to order this data set? Downloadable Data
  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?
    • Availability in digital form:
      Data format: This WinZip (version 9.0) file contains the color-hillshade relief GeoTIFF image, the TIFF world file, and the associated metadata files. in format GeoTIFF Size: 48
      Network links: http://pubs.usgs.gov/of/2009/1151/data/basemap/clrhshd_poto.zip
    • Cost to order the data: None.

  5. What hardware or software do I need in order to use the data set?
    This WinZip contains a GeoTIFF image and an accompanying world file. The user must have software capable of uncompressing the WinZip file. To simply view the image, any software capable of reading a TIFF file is sufficient. To view the image in its geospatial location, the user must have software that is either capable of reading the header information in the GeoTIFF, or alternatively reading the registration information in the TIFF world file.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
Woods Hole Coastal and Marine Science Center
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)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2009-1151/clrhshd_poto.tif.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:20:25 2021