Spatial Coverage


Definition

The <Spatial_Coverage> field specifies the geographic and vertical (altitude, depth) coverage of the data.

  •  <Southermost_Latitude> The southernmost geographic latitude covered by the data. From: 0 - 90° North or 0 - 90° South.
  • <Northernmost_Latitude> The northernmost geographic latitude covered by the data. From: 0 - 90° North or 0 - 90° South.
  • <Westernmost_Longitude> The westernmost geographic longitude covered by the data. From: 0 - 180° east or 0 - 180° west. The Prime Meridian is 0 degrees, measured positive (+) eastwards of the PM.
  • <Easternmost_Longitude>The easternmost geographic longitude covered by the data. From: 0 - 180° east or 0 - 180° west. The Prime Meridian is 0 degrees, measured positive (+) eastwards of the PM.
  • <Minimum_Altitude> The altitude level, which represents the lower limit of data coverage. Units must be specified.
  • <Maximum_Altitude> The altitude level, which represents the higher limit of data coverage. Units must be specified.
  • <Minimum_Depth>The depth level, which represents the upper-most depth of data coverage. Units must be specified.
  • <Maximum_Depth>The depth level, which represents the lowest depth of data coverage. Units must be specified.
 
Syntax

<Spatial_Coverage>
 <Southernmost_Latitude>0 - 90° North or 0 - 90° South</Southernmost_Latitude>
    <Northernmost_Latitude>0 - 90° North or 0 - 90° South</Northernmost_Latitude>
    <Westernmost_Longitude>0 - 180° east or 0 - 180° west</Westernmost_Longitude>
    <Easternmost_Longitude>0 - 180° east or 0 - 180° west</Easternmost_Longitude>
    <Minimum_Altitude> Text up to 80 characters</Minimum_Altitude>
    <Maximum_Altitude> Text up to 80 characters</Maximum_Altitude>
    <Minimum_Depth> Text up to 80 characters</Minimum_Depth>
    <Maximum_Depth> Text up to 80 characters</Maximum_Depth>
</Spatial_Coverage>


  • Characters may be selected from the printable ASCII character set.
  • A minus sign, "-", placed immediately before the latitude value indicates a latitude south of the Equator (defined as 0 degrees latitude).  A minus sign, "-", placed immediately before the longitude value indicates a longitude west of the Prime Meridian (defined as 0 degrees). Latitude north of the Equator (positive) and a longitude east of the Prime Meridian (positive) are assumed if minus signs are not entered before the latitude and longitude values.
N, S, E, or W do not have to be specified, but can be used in place of minus signs. N indicates latitude North of the Equator, S indicates latitude South of the Equator, E indicates longitude East of the Prime Meridian, and W indicates longitude West of the Prime Meridian.
 
Usage
The <Spatial_Coverage> field is highly recommended and may be repeatable.
  • Each field within <Spatial_Coverage> is optional and may not be repeated, with the following exception:
    • If latitude or longitudes are specified, all four values (<Northern- and <Southernmost_Latitude>, <Western- and <Easternmost_Longitude>) must be specified.
  • Point data can be specified by repeating <Northernmost_Latitude> and <Southernmost_Latitude> and <Westernmost_Longitude> and <Easternmost_Longitude> values.
  • Note:
      1. Pay careful attention to coordinates when specifying the bounding box of the data set. Remember that the <Southernmost_Latitude> may be in the Northern Hemisphere. Likewise, <Northernmost_Latitude> may be in the Southern Hemisphere, <Westernmost_Longitude> may be in the Eastern Hemisphere, and <Easternmost_Longitude> may be in the Western Hemisphere.
      2. If data coverage extends over the North Pole, the <Northernmost_Latitude> is 90N (or +90), the <Southernmost_Latitude> is the southernmost extent of the data, the <Easternmost_Longitude> is 180E (or +180), and the <Westernmost_Longitude> is 180W (or -180).
      3. If data coverage extends over the South Pole, the <Southernmost_Latitude> is 90S (or -90), the <Northernmost_Latitude> is the northernmost extent of the data, the <Easternmost_Longitude> is 180E (or +180), and the <Westernmost_Longitude> is 180W (or -180).
      4. If data coverage extends over the International Date Line (180 ° Longitude), the <Easternmost_Longitude> of the data will likely be in the Western Hemisphere, and the <Westernmost_Longitude> will likely be in the Eastern Hemisphere.
  • Some examples of altitude and depth units are 'm' (meters), 'km' (kilometers),'ft' (feet), 'surface', 'hPA' (hecto Pascals), and 'mb' (millibars).

 

Example

1. Bounding Box Data Set:
<Spatial_Coverage>
    <Southernmost_Latitude>25.0</Southernmost_Latitude>
    <Northernmost_Latitude>50.0</Northernmost_Latitude>
    <Westernmost_Longitude>-100.0</Westernmost_Longitude>
    <Easternmost_Longitude>-50.0</Easternmost_Longitude>
    <Minimum_Altitude>5 miles</Minimum_Altitude>
    <Maximum_Altitude>10 miles</Maximum_Altitude>
    <Minimum_Depth>10 feet</Minimum_Depth>
    <Maximum_Depth>100 feet</Maximum_Depth>
 </Spatial_Coverage>


2. Global Data Set:
   <Spatial_Coverage>
      <Southernmost_Latitude>90S</Southernmost_Latitude>
      <Northernmost_Latitude>90N</Northernmost_Latitude>
      <Westernmost_Longitude>180W</Westernmost_Longitude>
      <Easternmost_Longitude>180E</Easternmost_Longitude>
   </Spatial_Coverage>


3. Point Data Set:
   <Spatial_Coverage>
      <Southernmost_Latitude>-61</Southernmost_Latitude>
      <Northernmost_Latitude>-61</Northernmost_Latitude>
      <Westernmost_Longitude>-46</Westernmost_Longitude>
      <Easternmost_Longitude>-46</Easternmost_Longitude>
   </Spatial_Coverage>

 

This document should be cited as:
Directory Interchange Format (DIF) Writer's Guide, 2015.
Global Change Master Directory.
National Aeronautics and Space Administration.
[http://gcmd.nasa.gov/add/difguide/].

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