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Nighttime Lights of North America
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Nighttime Lights of North America

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Frequently-anticipated questions:

What does this data set describe?

Title: Nighttime Lights of North America
Abstract:
This map layer is an image of nighttime lights for North America, including the Caribbean and most of Mexico. The data were collected in 1996 and 1997 as part of the Defense Meteorological Satellite Program (DMSP). The data available through the National Atlas of the United States are in GeoTIFF format. This is a revised version of the May 2002 map layer, with a corrected shoreline for Greenland.

Supplemental_Information:
The Defense Meteorological Satellite Program (DMSP) satellites collect visible and infrared cloud imagery as well as monitoring the atmospheric, oceanographic, hydrologic, cryospheric and near-Earth space environments. The DMSP program maintains a constellation of two, sun-synchronous, near-polar orbiting satellites. The orbital period is 101 minutes and inclination is 99 degrees. The atmospheric and oceanographic sensors record radiances at visible, infrared and microwave wavelengths. The solar-geophysical sensors measure ionospheric plasma fluxes, densities, temperatures and velocities.

The OLS (Operational Linescan System) visible band (0.4-1.1 micrometers) is used to locate recurring nighttime lights. The thermal OLS band (10.5-12.5 micrometers) is used to screen for cloud free orbits. During the periods 16-21 March, 1996, 5-14 January, 1997, and 3-12 February, 1997, the gain on the OLS sensor was turned down to 24 from the normal 64 decibels. The result was an image in which urban centers do not saturate the signal.

DMSP visible and infrared imagery of clouds covers a 3,000 km swath, thus each satellite provides global coverage of both daytime and nighttime conditions each day. The field view of the microwave imagers and sounders is only 1,500 km, thus approximately 3 days data are required for one instrument to provide global coverage at equatorial latitudes. The solar-geophysical instruments make in-situ measurements of ionospheric parameters, some of which vary very rapidly.

This program is a joint effort with extensive collaboration between the Defense Meteorological Satellite Program Office, Air Force Global

Weather Central, the Strategic Environmental Research and Development

Program, the Office of the Federal Coordinator for Meteorological Services and Supporting Research, and the National Aeronautics and Space Administration.

Further information on the Defense Meterological Satellite Program can be found at <http://dmsp.ngdc.noaa.gov/dmsp.html>.

The associated world file is included as part of the GeoTIFF. The contents of the world file are: 

769.4780
0.000000
0.000000
-769.4780
-6086744.0000
4485901.0000
  1. How should this data set be cited?

    National Geophysical Data Center, 200301, Nighttime Lights of North America: National Atlas of the United States, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: 166.00
    East_Bounding_Coordinate: -4.00
    North_Bounding_Coordinate: 83.00
    South_Bounding_Coordinate: 15.00

  3. What does it look like?

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

    Beginning_Date: 16-Mar-1996
    Ending_Date: 12-Feb-1997
    Currentness_Reference: Ground condition

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

  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 9448 x 13471, type Grid Cell

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

      The map projection used is Lambert Azimuthal Equal Area.

      Projection parameters:
      Longitude_of_Projection_Center: -100.00
      Latitude_of_Projection_Center: 45.00
      False_Easting: 0.0
      False_Northing: 0.0

      Planar coordinates are encoded using Row and column
      Abscissae (x-coordinates) are specified to the nearest 769.478
      Ordinates (y-coordinates) are specified to the nearest 769.478
      Planar coordinates are specified in Meters

      The horizontal datum used is None.
      The ellipsoid used is Sphere.
      The semi-major axis of the ellipsoid used is 6370997.0.
      The flattening of the ellipsoid used is 1/1.0.

  7. How does the data set describe geographic features?

    Nighttime lights grid cell
    Any of the data elements in the nighttime lights file. (Source: National Atlas of the United States)

    Nighttime lights grid cell value
    The value is a measure of the intensity of nighttime lights in the grid cell. Light intensity is described by a range of values, where smaller values represent higher intensity, and larger values represent lower intensity. (Source: National Atlas of the United States)

    ValueDefinition
    255Water

    Range of values
    Minimum:0
    Maximum:72

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

    • National Geophysical Data Center

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    NOAA/NESDIS, National Geophysical Data Center
    c/o Dr. Christopher D. Elvidge
    E/GC2, 325 Broadway
    Boulder, CO 80305
    USA

    303-497-6121 (voice)
    303-497-6513 (FAX)
    Chris.Elvidge@noaa.gov

Why was the data set created?

These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. No responsibility is assumed by the National Atlas of the United States in the use of these data.

How was the data set created?

  1. From what previous works were the data drawn?

    DMSPOLS (source 1 of 6)
    National Geophysical Data Center, 1997, DMSP - OLS data: NOAA/NESDIS, National Geophysical Data Center, Boulder, CO.

    Type_of_Source_Media: magnetic tape
    Source_Contribution: Nighttime lights information

    shorelp020l (source 2 of 6)
    National Atlas of the United States, 1999, Shoreline file in Lambert Azimuthal Equal Area projection: National Atlas of the United States, Reston, VA.

    Type_of_Source_Media: internal file
    Source_Contribution: Shoreline mask for area of coverage.

    LIGHTS_IMAGE2001 (source 3 of 6)
    National Geophysical Data Center, 200105, Nighttime Lights of North America: National Atlas of the United States, Reston, VA.

    Type_of_Source_Media: online
    Source_Contribution: Nighttime Lights TIFF image.

    GRDMSKI (source 4 of 6)
    National Atlas of the United States, 200205, North America Land/Water Mask: National Atlas of the United States, Reston, VA.

    Type_of_Source_Media: ftp site
    Source_Contribution: Shoreline information

    LIGHTS_IMAGE200205 (source 5 of 6)
    National Geophysical Data Center, 200205, Nighttime Lights of North America: National Atlas of the United States, Reston, VA.

    Type_of_Source_Media: online
    Source_Contribution: Nighttime Lights TIFF image.

    WVS (source 6 of 6)
    National Imagery and Mapping Agency, 1990, World Vector Shoreline: National Imagery and Mapping Agency, Bethesda, MD.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution: Shoreline information.

  2. How were the data generated, processed, and modified?

    Date: 1999 (process 1 of 3)
    During the periods from 16-21 March, 1996, 5-14 January, 1997, and 3- 12 February, 1997, the gain on the OLS sensor was turned down to 24 from the normal 64 decibels. The result was an image in which urban centers do not saturate the signal. The National Geophysical Data Center (NGDC) received the complete DMSP data stream in the same form in which it was received at Air Force Weather Agency. NGDC processed the map layer to restore data lost during transmission and compute satellite positions.

    In addition, very near infrared (VNIR) emission sources and clouds for each of the suborbits were detected and geolocated, and the data were composited. Image time series analysis was used to distinguish lights produced by cities, towns, and industrial facilities from sensor noise and ephemeral lights arising from fires and lightning. The time series approach was required to ensure that each land area was covered with sufficient cloud free observations to determine the presence or absence of VNIR emission sources.

    The worldwide nighttime lights data file (DMSPOLS) was received in TIFF format. The file was converted to JPEG format and resampled in Adobe Photoshop to reduce the file size. The file was then converted to ESRI GRID format, the image was truncated using the shoreline mask (shorelp020l), and the value of the water areas was set to 255. The file was converted back to TIFF format.

    Data sources used in this process:

    • DMSPOLS
    • shorelp020l

    Data sources produced in this process:

    • LIGHTS_IMAGE2001

    Date: May-2002 (process 2 of 3)
    Coastlines in Canada, Mexico, Russia, and in the Caribbean were corrected. A GeoTIFF Revision 1.0 header was added and PackBits compression was applied to the image.

    Data sources used in this process:

    • LIGHTS_IMAGE2001
    • GRDMSKI

    Data sources produced in this process:

    • LIGHTS_IMAGE200205

    Date: Dec-2002 (process 3 of 3)
    The coastline of Greenland was replaced by a new, corrected version derived from World Vector Shoreline (WVS). This image contains no thematic data for Greenland; the new data were inserted only to maintain consistency with other National Atlas data layers.

    Data sources used in this process:

    • LIGHTS_IMAGE200205
    • WVS

  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?

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

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

    This map layer contains nighttime lights information for all of North America excluding southern Mexico, and for the Caribbean, parts of Russia, and Greenland.

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

    No checks for logical consistency were performed on this map layer.

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:
None. Acknowledgment of the National Geophysical Data Center and (or) the National Atlas of the United States of America would be appreciated in products derived from these data.

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

    Earth Science Information Center, U.S. Geological Survey
    507 National Center
    Reston, VA 20192

    1-888-ASK-USGS (1-888-275-8747) (voice)

    Contact_Instructions:
    In addition to the address above there are other ESIC offices throughout the country. A full list of these offices is at <http://geography.usgs.gov/esic/esic_index.html>.
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. No responsibility is assumed by the U.S. Geological Survey in the use of these data.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 26-Sep-2005
Metadata author:
Peg Rawson
National Atlas of the United States
12201 Sunrise Valley Drive
Reston, VA 20192
USA

703-648-4183 (voice)
atlasmail@usgs.gov

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


 
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