Side Looking Airborne Radar (SLAR) Mosaics Data Dictionary Active

By Earth Resources Observation and Science (EROS) Center July 16, 2021

The Data Dictionaries are a set of information describing the contents, format, and structure of elements for EarthExplorer products.

Acquisition Date Acquisition Facility Coordinates - Decimal Degrees Coordinates - Degrees, Minutes, Seconds Depression Angle Entity ID Frequency Look Direction Map Name Mosaic Scale Project Range Sensor Signal

Acquisition Date

Field Definition: The acquisition date refers to the year, month, and day the data were acquired.

Values:
Format: YYYY/MM/DD
YYYY = Year
MM = Month
DD = Day

Acquisition Facility

Field Definition: The company or facility that acquired the imagery.

Coordinates - Decimal Degrees

Field Definition: The latitude and longitude are provided in decimal degrees for the following fields:

Values:
Scene Center Latitude and Longitude
Northeast (NE) Corner Latitude and Longitude
Northwest (NW) Corner Latitude and Longitude
Southeast (SE) Corner Latitude and Longitude
Southwest (SW) Corner Latitude and Longitude

Latitude Format Decimal Degrees: -90.000 through 90.000
Longitude Format Decimal Degrees: -180.000 through 180.000

Number of decimal places will vary by dataset – check collection in EE.

Coordinates - Degrees, Minutes, Seconds

Field Definition: The latitude and longitude are provided in degrees, minutes, and seconds for the following fields:

Longitude Format:
DDDMMSS.SSH
DDD = Degree(s) with a range of 0 through 180
MM = Minute(s) with a range of 0 through 59
SS.SS = Second(s) with a range of 0 through 59.99
H = Hemisphere with E for east and W for west

Latitude Format:
DDMMSS.SSH
DD = Degree(s) with a range of 0 through 90
MM = Minutes(s) with a range of 0 through 59
SS.SS = Second(s) with a range of 0 through 59.99
H = Hemisphere with N for north and S for south

Depression Angle

Field Definition: This field identifies the depression angle (degrees) of the radar signal.

Entity ID

Field Definition: This field is used to identify data by assigning a unique series of letters and numbers to an image.

Format:
DDAPPPPPPFFFFFF
Where DD = Data set Designator = SI
A = Agency, where 1 = USGS
PPPPPP = Project Code
FFFFF - File Number

Example:
SI1REPA00820898

Frequency

Field Definition: This field identifies the frequency (gigahertz) or wavelength (centimeters) used by the signal.

Values:
X = 2.40 - 3.75 cm wavelength; 8 - 12.5 GHz frequency
L = 15 - 30 cm wavelength; 1 - 2 GHz frequency

Look Direction

Field Definition: Since the microwaves travel at the speed of light in air, the timing of each portion of the returned signal establishes its image position in the range or look direction (perpendicular to the flightline).

Values:
  N = North
  S = South
  E = East
  W = West

Map Name

Field Definition: The name of the corresponding 1:250,000-scale map for the scene.

Mosaic Scale

Field Definition: The scale of the mosaic is the ratio of a distance on the map to the corresponding distance on the ground.

Example:
250 = 1:250,000-scale map

Project

Field Definition: The project assigned to this mosaic.

Range

Field Definition: The range (or cross track) is a measure of the “line-of-sight’ distance from the radar to the target.

Example:
Near
Mix
Far

Sensor

Field Definition: The sensor used to acquire the data such as Real Aperture or Synthetic Aperture.

Values:
S26 = Real Aperture
S27 = Synthetic Aperture

Signal

Field Definition: The polarization of the radar signal such as HH = horizontally transmitted and horizontally returned.

Overview